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- # SPDX-License-Identifier: GPL-2.0
- # Select 32 or 64 bit
- config 64BIT
- bool "64-bit kernel" if "$(ARCH)" = "x86"
- default "$(ARCH)" != "i386"
- help
- Say yes to build a 64-bit kernel - formerly known as x86_64
- Say no to build a 32-bit kernel - formerly known as i386
- config X86_32
- def_bool y
- depends on !64BIT
- # Options that are inherently 32-bit kernel only:
- select ARCH_WANT_IPC_PARSE_VERSION
- select CLKSRC_I8253
- select CLONE_BACKWARDS
- select GENERIC_VDSO_32
- select HAVE_DEBUG_STACKOVERFLOW
- select KMAP_LOCAL
- select MODULES_USE_ELF_REL
- select OLD_SIGACTION
- select ARCH_SPLIT_ARG64
- config X86_64
- def_bool y
- depends on 64BIT
- # Options that are inherently 64-bit kernel only:
- select ARCH_HAS_GIGANTIC_PAGE
- select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
- select ARCH_SUPPORTS_PER_VMA_LOCK
- select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
- select HAVE_ARCH_SOFT_DIRTY
- select MODULES_USE_ELF_RELA
- select NEED_DMA_MAP_STATE
- select SWIOTLB
- select ARCH_HAS_ELFCORE_COMPAT
- select ZONE_DMA32
- select EXECMEM if DYNAMIC_FTRACE
- config FORCE_DYNAMIC_FTRACE
- def_bool y
- depends on X86_32
- depends on FUNCTION_TRACER
- select DYNAMIC_FTRACE
- help
- We keep the static function tracing (!DYNAMIC_FTRACE) around
- in order to test the non static function tracing in the
- generic code, as other architectures still use it. But we
- only need to keep it around for x86_64. No need to keep it
- for x86_32. For x86_32, force DYNAMIC_FTRACE.
- #
- # Arch settings
- #
- # ( Note that options that are marked 'if X86_64' could in principle be
- # ported to 32-bit as well. )
- #
- config X86
- def_bool y
- #
- # Note: keep this list sorted alphabetically
- #
- select ACPI_LEGACY_TABLES_LOOKUP if ACPI
- select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
- select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
- select ARCH_32BIT_OFF_T if X86_32
- select ARCH_CLOCKSOURCE_INIT
- select ARCH_CONFIGURES_CPU_MITIGATIONS
- select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
- select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
- select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
- select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
- select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
- select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
- select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
- select ARCH_HAS_CACHE_LINE_SIZE
- select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
- select ARCH_HAS_CPU_FINALIZE_INIT
- select ARCH_HAS_CPU_PASID if IOMMU_SVA
- select ARCH_HAS_CURRENT_STACK_POINTER
- select ARCH_HAS_DEBUG_VIRTUAL
- select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
- select ARCH_HAS_DEVMEM_IS_ALLOWED
- select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN
- select ARCH_HAS_EARLY_DEBUG if KGDB
- select ARCH_HAS_ELF_RANDOMIZE
- select ARCH_HAS_FAST_MULTIPLIER
- select ARCH_HAS_FORTIFY_SOURCE
- select ARCH_HAS_GCOV_PROFILE_ALL
- select ARCH_HAS_KCOV if X86_64
- select ARCH_HAS_KERNEL_FPU_SUPPORT
- select ARCH_HAS_MEM_ENCRYPT
- select ARCH_HAS_MEMBARRIER_SYNC_CORE
- select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
- select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
- select ARCH_HAS_PMEM_API if X86_64
- select ARCH_HAS_PTE_DEVMAP if X86_64
- select ARCH_HAS_PTE_SPECIAL
- select ARCH_HAS_HW_PTE_YOUNG
- select ARCH_HAS_NONLEAF_PMD_YOUNG if PGTABLE_LEVELS > 2
- select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
- select ARCH_HAS_COPY_MC if X86_64
- select ARCH_HAS_SET_MEMORY
- select ARCH_HAS_SET_DIRECT_MAP
- select ARCH_HAS_STRICT_KERNEL_RWX
- select ARCH_HAS_STRICT_MODULE_RWX
- select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
- select ARCH_HAS_SYSCALL_WRAPPER
- select ARCH_HAS_UBSAN
- select ARCH_HAS_DEBUG_WX
- select ARCH_HAS_ZONE_DMA_SET if EXPERT
- select ARCH_HAVE_NMI_SAFE_CMPXCHG
- select ARCH_HAVE_EXTRA_ELF_NOTES
- select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
- select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
- select ARCH_MIGHT_HAVE_PC_PARPORT
- select ARCH_MIGHT_HAVE_PC_SERIO
- select ARCH_STACKWALK
- select ARCH_SUPPORTS_ACPI
- select ARCH_SUPPORTS_ATOMIC_RMW
- select ARCH_SUPPORTS_DEBUG_PAGEALLOC
- select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64
- select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
- select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
- select ARCH_SUPPORTS_CFI_CLANG if X86_64
- select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG
- select ARCH_SUPPORTS_LTO_CLANG
- select ARCH_SUPPORTS_LTO_CLANG_THIN
- select ARCH_SUPPORTS_RT
- select ARCH_USE_BUILTIN_BSWAP
- select ARCH_USE_CMPXCHG_LOCKREF if X86_CMPXCHG64
- select ARCH_USE_MEMTEST
- select ARCH_USE_QUEUED_RWLOCKS
- select ARCH_USE_QUEUED_SPINLOCKS
- select ARCH_USE_SYM_ANNOTATIONS
- select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
- select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
- select ARCH_WANTS_DYNAMIC_TASK_STRUCT
- select ARCH_WANTS_NO_INSTR
- select ARCH_WANT_GENERAL_HUGETLB
- select ARCH_WANT_HUGE_PMD_SHARE
- select ARCH_WANT_LD_ORPHAN_WARN
- select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP if X86_64
- select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if X86_64
- select ARCH_WANTS_THP_SWAP if X86_64
- select ARCH_HAS_PARANOID_L1D_FLUSH
- select BUILDTIME_TABLE_SORT
- select CLKEVT_I8253
- select CLOCKSOURCE_WATCHDOG
- # Word-size accesses may read uninitialized data past the trailing \0
- # in strings and cause false KMSAN reports.
- select DCACHE_WORD_ACCESS if !KMSAN
- select DYNAMIC_SIGFRAME
- select EDAC_ATOMIC_SCRUB
- select EDAC_SUPPORT
- select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
- select GENERIC_CLOCKEVENTS_BROADCAST_IDLE if GENERIC_CLOCKEVENTS_BROADCAST
- select GENERIC_CLOCKEVENTS_MIN_ADJUST
- select GENERIC_CMOS_UPDATE
- select GENERIC_CPU_AUTOPROBE
- select GENERIC_CPU_DEVICES
- select GENERIC_CPU_VULNERABILITIES
- select GENERIC_EARLY_IOREMAP
- select GENERIC_ENTRY
- select GENERIC_IOMAP
- select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
- select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
- select GENERIC_IRQ_MIGRATION if SMP
- select GENERIC_IRQ_PROBE
- select GENERIC_IRQ_RESERVATION_MODE
- select GENERIC_IRQ_SHOW
- select GENERIC_PENDING_IRQ if SMP
- select GENERIC_PTDUMP
- select GENERIC_SMP_IDLE_THREAD
- select GENERIC_TIME_VSYSCALL
- select GENERIC_GETTIMEOFDAY
- select GENERIC_VDSO_TIME_NS
- select GENERIC_VDSO_OVERFLOW_PROTECT
- select GUP_GET_PXX_LOW_HIGH if X86_PAE
- select HARDIRQS_SW_RESEND
- select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
- select HAS_IOPORT
- select HAVE_ACPI_APEI if ACPI
- select HAVE_ACPI_APEI_NMI if ACPI
- select HAVE_ALIGNED_STRUCT_PAGE
- select HAVE_ARCH_AUDITSYSCALL
- select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
- select HAVE_ARCH_HUGE_VMALLOC if X86_64
- select HAVE_ARCH_JUMP_LABEL
- select HAVE_ARCH_JUMP_LABEL_RELATIVE
- select HAVE_ARCH_KASAN if X86_64
- select HAVE_ARCH_KASAN_VMALLOC if X86_64
- select HAVE_ARCH_KFENCE
- select HAVE_ARCH_KMSAN if X86_64
- select HAVE_ARCH_KGDB
- select HAVE_ARCH_MMAP_RND_BITS if MMU
- select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
- select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
- select HAVE_ARCH_PREL32_RELOCATIONS
- select HAVE_ARCH_SECCOMP_FILTER
- select HAVE_ARCH_THREAD_STRUCT_WHITELIST
- select HAVE_ARCH_STACKLEAK
- select HAVE_ARCH_TRACEHOOK
- select HAVE_ARCH_TRANSPARENT_HUGEPAGE
- select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
- select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
- select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
- select HAVE_ARCH_VMAP_STACK if X86_64
- select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
- select HAVE_ARCH_WITHIN_STACK_FRAMES
- select HAVE_ASM_MODVERSIONS
- select HAVE_CMPXCHG_DOUBLE
- select HAVE_CMPXCHG_LOCAL
- select HAVE_CONTEXT_TRACKING_USER if X86_64
- select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER
- select HAVE_C_RECORDMCOUNT
- select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
- select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
- select HAVE_BUILDTIME_MCOUNT_SORT
- select HAVE_DEBUG_KMEMLEAK
- select HAVE_DMA_CONTIGUOUS
- select HAVE_DYNAMIC_FTRACE
- select HAVE_DYNAMIC_FTRACE_WITH_REGS
- select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
- select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
- select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
- select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
- select HAVE_EBPF_JIT
- select HAVE_EFFICIENT_UNALIGNED_ACCESS
- select HAVE_EISA
- select HAVE_EXIT_THREAD
- select HAVE_GUP_FAST
- select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
- select HAVE_FTRACE_MCOUNT_RECORD
- select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
- select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
- select HAVE_FUNCTION_TRACER
- select HAVE_GCC_PLUGINS
- select HAVE_HW_BREAKPOINT
- select HAVE_IOREMAP_PROT
- select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
- select HAVE_IRQ_TIME_ACCOUNTING
- select HAVE_JUMP_LABEL_HACK if HAVE_OBJTOOL
- select HAVE_KERNEL_BZIP2
- select HAVE_KERNEL_GZIP
- select HAVE_KERNEL_LZ4
- select HAVE_KERNEL_LZMA
- select HAVE_KERNEL_LZO
- select HAVE_KERNEL_XZ
- select HAVE_KERNEL_ZSTD
- select HAVE_KPROBES
- select HAVE_KPROBES_ON_FTRACE
- select HAVE_FUNCTION_ERROR_INJECTION
- select HAVE_KRETPROBES
- select HAVE_RETHOOK
- select HAVE_LIVEPATCH if X86_64
- select HAVE_MIXED_BREAKPOINTS_REGS
- select HAVE_MOD_ARCH_SPECIFIC
- select HAVE_MOVE_PMD
- select HAVE_MOVE_PUD
- select HAVE_NOINSTR_HACK if HAVE_OBJTOOL
- select HAVE_NMI
- select HAVE_NOINSTR_VALIDATION if HAVE_OBJTOOL
- select HAVE_OBJTOOL if X86_64
- select HAVE_OPTPROBES
- select HAVE_PAGE_SIZE_4KB
- select HAVE_PCSPKR_PLATFORM
- select HAVE_PERF_EVENTS
- select HAVE_PERF_EVENTS_NMI
- select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
- select HAVE_PCI
- select HAVE_PERF_REGS
- select HAVE_PERF_USER_STACK_DUMP
- select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
- select MMU_GATHER_MERGE_VMAS
- select HAVE_POSIX_CPU_TIMERS_TASK_WORK
- select HAVE_REGS_AND_STACK_ACCESS_API
- select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC || STACK_VALIDATION
- select HAVE_FUNCTION_ARG_ACCESS_API
- select HAVE_SETUP_PER_CPU_AREA
- select HAVE_SOFTIRQ_ON_OWN_STACK
- select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
- select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
- select HAVE_STATIC_CALL
- select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
- select HAVE_PREEMPT_DYNAMIC_CALL
- select HAVE_RSEQ
- select HAVE_RUST if X86_64
- select HAVE_SYSCALL_TRACEPOINTS
- select HAVE_UACCESS_VALIDATION if HAVE_OBJTOOL
- select HAVE_UNSTABLE_SCHED_CLOCK
- select HAVE_USER_RETURN_NOTIFIER
- select HAVE_GENERIC_VDSO
- select VDSO_GETRANDOM if X86_64
- select HOTPLUG_PARALLEL if SMP && X86_64
- select HOTPLUG_SMT if SMP
- select HOTPLUG_SPLIT_STARTUP if SMP && X86_32
- select IRQ_FORCED_THREADING
- select LOCK_MM_AND_FIND_VMA
- select NEED_PER_CPU_EMBED_FIRST_CHUNK
- select NEED_PER_CPU_PAGE_FIRST_CHUNK
- select NEED_SG_DMA_LENGTH
- select NUMA_MEMBLKS if NUMA
- select PCI_DOMAINS if PCI
- select PCI_LOCKLESS_CONFIG if PCI
- select PERF_EVENTS
- select RTC_LIB
- select RTC_MC146818_LIB
- select SPARSE_IRQ
- select SYSCTL_EXCEPTION_TRACE
- select THREAD_INFO_IN_TASK
- select TRACE_IRQFLAGS_SUPPORT
- select TRACE_IRQFLAGS_NMI_SUPPORT
- select USER_STACKTRACE_SUPPORT
- select HAVE_ARCH_KCSAN if X86_64
- select PROC_PID_ARCH_STATUS if PROC_FS
- select HAVE_ARCH_NODE_DEV_GROUP if X86_SGX
- select FUNCTION_ALIGNMENT_16B if X86_64 || X86_ALIGNMENT_16
- select FUNCTION_ALIGNMENT_4B
- imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
- select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
- config INSTRUCTION_DECODER
- def_bool y
- depends on KPROBES || PERF_EVENTS || UPROBES
- config OUTPUT_FORMAT
- string
- default "elf32-i386" if X86_32
- default "elf64-x86-64" if X86_64
- config LOCKDEP_SUPPORT
- def_bool y
- config STACKTRACE_SUPPORT
- def_bool y
- config MMU
- def_bool y
- config ARCH_MMAP_RND_BITS_MIN
- default 28 if 64BIT
- default 8
- config ARCH_MMAP_RND_BITS_MAX
- default 32 if 64BIT
- default 16
- config ARCH_MMAP_RND_COMPAT_BITS_MIN
- default 8
- config ARCH_MMAP_RND_COMPAT_BITS_MAX
- default 16
- config SBUS
- bool
- config GENERIC_ISA_DMA
- def_bool y
- depends on ISA_DMA_API
- config GENERIC_CSUM
- bool
- default y if KMSAN || KASAN
- config GENERIC_BUG
- def_bool y
- depends on BUG
- select GENERIC_BUG_RELATIVE_POINTERS if X86_64
- config GENERIC_BUG_RELATIVE_POINTERS
- bool
- config ARCH_MAY_HAVE_PC_FDC
- def_bool y
- depends on ISA_DMA_API
- config GENERIC_CALIBRATE_DELAY
- def_bool y
- config ARCH_HAS_CPU_RELAX
- def_bool y
- config ARCH_HIBERNATION_POSSIBLE
- def_bool y
- config ARCH_SUSPEND_POSSIBLE
- def_bool y
- config AUDIT_ARCH
- def_bool y if X86_64
- config KASAN_SHADOW_OFFSET
- hex
- depends on KASAN
- default 0xdffffc0000000000
- config HAVE_INTEL_TXT
- def_bool y
- depends on INTEL_IOMMU && ACPI
- config X86_64_SMP
- def_bool y
- depends on X86_64 && SMP
- config ARCH_SUPPORTS_UPROBES
- def_bool y
- config FIX_EARLYCON_MEM
- def_bool y
- config DYNAMIC_PHYSICAL_MASK
- bool
- config PGTABLE_LEVELS
- int
- default 5 if X86_5LEVEL
- default 4 if X86_64
- default 3 if X86_PAE
- default 2
- config CC_HAS_SANE_STACKPROTECTOR
- bool
- default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC) $(CLANG_FLAGS)) if 64BIT
- default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC) $(CLANG_FLAGS))
- help
- We have to make sure stack protector is unconditionally disabled if
- the compiler produces broken code or if it does not let us control
- the segment on 32-bit kernels.
- menu "Processor type and features"
- config SMP
- bool "Symmetric multi-processing support"
- help
- This enables support for systems with more than one CPU. If you have
- a system with only one CPU, say N. If you have a system with more
- than one CPU, say Y.
- If you say N here, the kernel will run on uni- and multiprocessor
- machines, but will use only one CPU of a multiprocessor machine. If
- you say Y here, the kernel will run on many, but not all,
- uniprocessor machines. On a uniprocessor machine, the kernel
- will run faster if you say N here.
- Note that if you say Y here and choose architecture "586" or
- "Pentium" under "Processor family", the kernel will not work on 486
- architectures. Similarly, multiprocessor kernels for the "PPro"
- architecture may not work on all Pentium based boards.
- People using multiprocessor machines who say Y here should also say
- Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
- Management" code will be disabled if you say Y here.
- See also <file:Documentation/arch/x86/i386/IO-APIC.rst>,
- <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
- <http://www.tldp.org/docs.html#howto>.
- If you don't know what to do here, say N.
- config X86_X2APIC
- bool "Support x2apic"
- depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
- help
- This enables x2apic support on CPUs that have this feature.
- This allows 32-bit apic IDs (so it can support very large systems),
- and accesses the local apic via MSRs not via mmio.
- Some Intel systems circa 2022 and later are locked into x2APIC mode
- and can not fall back to the legacy APIC modes if SGX or TDX are
- enabled in the BIOS. They will boot with very reduced functionality
- without enabling this option.
- If you don't know what to do here, say N.
- config X86_POSTED_MSI
- bool "Enable MSI and MSI-x delivery by posted interrupts"
- depends on X86_64 && IRQ_REMAP
- help
- This enables MSIs that are under interrupt remapping to be delivered as
- posted interrupts to the host kernel. Interrupt throughput can
- potentially be improved by coalescing CPU notifications during high
- frequency bursts.
- If you don't know what to do here, say N.
- config X86_MPPARSE
- bool "Enable MPS table" if ACPI
- default y
- depends on X86_LOCAL_APIC
- help
- For old smp systems that do not have proper acpi support. Newer systems
- (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
- config X86_CPU_RESCTRL
- bool "x86 CPU resource control support"
- depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
- select KERNFS
- select PROC_CPU_RESCTRL if PROC_FS
- help
- Enable x86 CPU resource control support.
- Provide support for the allocation and monitoring of system resources
- usage by the CPU.
- Intel calls this Intel Resource Director Technology
- (Intel(R) RDT). More information about RDT can be found in the
- Intel x86 Architecture Software Developer Manual.
- AMD calls this AMD Platform Quality of Service (AMD QoS).
- More information about AMD QoS can be found in the AMD64 Technology
- Platform Quality of Service Extensions manual.
- Say N if unsure.
- config X86_FRED
- bool "Flexible Return and Event Delivery"
- depends on X86_64
- help
- When enabled, try to use Flexible Return and Event Delivery
- instead of the legacy SYSCALL/SYSENTER/IDT architecture for
- ring transitions and exception/interrupt handling if the
- system supports it.
- config X86_BIGSMP
- bool "Support for big SMP systems with more than 8 CPUs"
- depends on SMP && X86_32
- help
- This option is needed for the systems that have more than 8 CPUs.
- config X86_EXTENDED_PLATFORM
- bool "Support for extended (non-PC) x86 platforms"
- default y
- help
- If you disable this option then the kernel will only support
- standard PC platforms. (which covers the vast majority of
- systems out there.)
- If you enable this option then you'll be able to select support
- for the following non-PC x86 platforms, depending on the value of
- CONFIG_64BIT.
- 32-bit platforms (CONFIG_64BIT=n):
- Goldfish (Android emulator)
- AMD Elan
- RDC R-321x SoC
- SGI 320/540 (Visual Workstation)
- STA2X11-based (e.g. Northville)
- Moorestown MID devices
- 64-bit platforms (CONFIG_64BIT=y):
- Numascale NumaChip
- ScaleMP vSMP
- SGI Ultraviolet
- If you have one of these systems, or if you want to build a
- generic distribution kernel, say Y here - otherwise say N.
- # This is an alphabetically sorted list of 64 bit extended platforms
- # Please maintain the alphabetic order if and when there are additions
- config X86_NUMACHIP
- bool "Numascale NumaChip"
- depends on X86_64
- depends on X86_EXTENDED_PLATFORM
- depends on NUMA
- depends on SMP
- depends on X86_X2APIC
- depends on PCI_MMCONFIG
- help
- Adds support for Numascale NumaChip large-SMP systems. Needed to
- enable more than ~168 cores.
- If you don't have one of these, you should say N here.
- config X86_VSMP
- bool "ScaleMP vSMP"
- select HYPERVISOR_GUEST
- select PARAVIRT
- depends on X86_64 && PCI
- depends on X86_EXTENDED_PLATFORM
- depends on SMP
- help
- Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
- supposed to run on these EM64T-based machines. Only choose this option
- if you have one of these machines.
- config X86_UV
- bool "SGI Ultraviolet"
- depends on X86_64
- depends on X86_EXTENDED_PLATFORM
- depends on NUMA
- depends on EFI
- depends on KEXEC_CORE
- depends on X86_X2APIC
- depends on PCI
- help
- This option is needed in order to support SGI Ultraviolet systems.
- If you don't have one of these, you should say N here.
- # Following is an alphabetically sorted list of 32 bit extended platforms
- # Please maintain the alphabetic order if and when there are additions
- config X86_GOLDFISH
- bool "Goldfish (Virtual Platform)"
- depends on X86_EXTENDED_PLATFORM
- help
- Enable support for the Goldfish virtual platform used primarily
- for Android development. Unless you are building for the Android
- Goldfish emulator say N here.
- config X86_INTEL_CE
- bool "CE4100 TV platform"
- depends on PCI
- depends on PCI_GODIRECT
- depends on X86_IO_APIC
- depends on X86_32
- depends on X86_EXTENDED_PLATFORM
- select X86_REBOOTFIXUPS
- select OF
- select OF_EARLY_FLATTREE
- help
- Select for the Intel CE media processor (CE4100) SOC.
- This option compiles in support for the CE4100 SOC for settop
- boxes and media devices.
- config X86_INTEL_MID
- bool "Intel MID platform support"
- depends on X86_EXTENDED_PLATFORM
- depends on X86_PLATFORM_DEVICES
- depends on PCI
- depends on X86_64 || (PCI_GOANY && X86_32)
- depends on X86_IO_APIC
- select I2C
- select DW_APB_TIMER
- select INTEL_SCU_PCI
- help
- Select to build a kernel capable of supporting Intel MID (Mobile
- Internet Device) platform systems which do not have the PCI legacy
- interfaces. If you are building for a PC class system say N here.
- Intel MID platforms are based on an Intel processor and chipset which
- consume less power than most of the x86 derivatives.
- config X86_INTEL_QUARK
- bool "Intel Quark platform support"
- depends on X86_32
- depends on X86_EXTENDED_PLATFORM
- depends on X86_PLATFORM_DEVICES
- depends on X86_TSC
- depends on PCI
- depends on PCI_GOANY
- depends on X86_IO_APIC
- select IOSF_MBI
- select INTEL_IMR
- select COMMON_CLK
- help
- Select to include support for Quark X1000 SoC.
- Say Y here if you have a Quark based system such as the Arduino
- compatible Intel Galileo.
- config X86_INTEL_LPSS
- bool "Intel Low Power Subsystem Support"
- depends on X86 && ACPI && PCI
- select COMMON_CLK
- select PINCTRL
- select IOSF_MBI
- help
- Select to build support for Intel Low Power Subsystem such as
- found on Intel Lynxpoint PCH. Selecting this option enables
- things like clock tree (common clock framework) and pincontrol
- which are needed by the LPSS peripheral drivers.
- config X86_AMD_PLATFORM_DEVICE
- bool "AMD ACPI2Platform devices support"
- depends on ACPI
- select COMMON_CLK
- select PINCTRL
- help
- Select to interpret AMD specific ACPI device to platform device
- such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
- I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
- implemented under PINCTRL subsystem.
- config IOSF_MBI
- tristate "Intel SoC IOSF Sideband support for SoC platforms"
- depends on PCI
- help
- This option enables sideband register access support for Intel SoC
- platforms. On these platforms the IOSF sideband is used in lieu of
- MSR's for some register accesses, mostly but not limited to thermal
- and power. Drivers may query the availability of this device to
- determine if they need the sideband in order to work on these
- platforms. The sideband is available on the following SoC products.
- This list is not meant to be exclusive.
- - BayTrail
- - Braswell
- - Quark
- You should say Y if you are running a kernel on one of these SoC's.
- config IOSF_MBI_DEBUG
- bool "Enable IOSF sideband access through debugfs"
- depends on IOSF_MBI && DEBUG_FS
- help
- Select this option to expose the IOSF sideband access registers (MCR,
- MDR, MCRX) through debugfs to write and read register information from
- different units on the SoC. This is most useful for obtaining device
- state information for debug and analysis. As this is a general access
- mechanism, users of this option would have specific knowledge of the
- device they want to access.
- If you don't require the option or are in doubt, say N.
- config X86_RDC321X
- bool "RDC R-321x SoC"
- depends on X86_32
- depends on X86_EXTENDED_PLATFORM
- select M486
- select X86_REBOOTFIXUPS
- help
- This option is needed for RDC R-321x system-on-chip, also known
- as R-8610-(G).
- If you don't have one of these chips, you should say N here.
- config X86_32_NON_STANDARD
- bool "Support non-standard 32-bit SMP architectures"
- depends on X86_32 && SMP
- depends on X86_EXTENDED_PLATFORM
- help
- This option compiles in the bigsmp and STA2X11 default
- subarchitectures. It is intended for a generic binary
- kernel. If you select them all, kernel will probe it one by
- one and will fallback to default.
- # Alphabetically sorted list of Non standard 32 bit platforms
- config X86_SUPPORTS_MEMORY_FAILURE
- def_bool y
- # MCE code calls memory_failure():
- depends on X86_MCE
- # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
- # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
- depends on X86_64 || !SPARSEMEM
- select ARCH_SUPPORTS_MEMORY_FAILURE
- config STA2X11
- bool "STA2X11 Companion Chip Support"
- depends on X86_32_NON_STANDARD && PCI
- select SWIOTLB
- select MFD_STA2X11
- select GPIOLIB
- help
- This adds support for boards based on the STA2X11 IO-Hub,
- a.k.a. "ConneXt". The chip is used in place of the standard
- PC chipset, so all "standard" peripherals are missing. If this
- option is selected the kernel will still be able to boot on
- standard PC machines.
- config X86_32_IRIS
- tristate "Eurobraille/Iris poweroff module"
- depends on X86_32
- help
- The Iris machines from EuroBraille do not have APM or ACPI support
- to shut themselves down properly. A special I/O sequence is
- needed to do so, which is what this module does at
- kernel shutdown.
- This is only for Iris machines from EuroBraille.
- If unused, say N.
- config SCHED_OMIT_FRAME_POINTER
- def_bool y
- prompt "Single-depth WCHAN output"
- depends on X86
- help
- Calculate simpler /proc/<PID>/wchan values. If this option
- is disabled then wchan values will recurse back to the
- caller function. This provides more accurate wchan values,
- at the expense of slightly more scheduling overhead.
- If in doubt, say "Y".
- menuconfig HYPERVISOR_GUEST
- bool "Linux guest support"
- help
- Say Y here to enable options for running Linux under various hyper-
- visors. This option enables basic hypervisor detection and platform
- setup.
- If you say N, all options in this submenu will be skipped and
- disabled, and Linux guest support won't be built in.
- if HYPERVISOR_GUEST
- config PARAVIRT
- bool "Enable paravirtualization code"
- depends on HAVE_STATIC_CALL
- help
- This changes the kernel so it can modify itself when it is run
- under a hypervisor, potentially improving performance significantly
- over full virtualization. However, when run without a hypervisor
- the kernel is theoretically slower and slightly larger.
- config PARAVIRT_XXL
- bool
- config PARAVIRT_DEBUG
- bool "paravirt-ops debugging"
- depends on PARAVIRT && DEBUG_KERNEL
- help
- Enable to debug paravirt_ops internals. Specifically, BUG if
- a paravirt_op is missing when it is called.
- config PARAVIRT_SPINLOCKS
- bool "Paravirtualization layer for spinlocks"
- depends on PARAVIRT && SMP
- help
- Paravirtualized spinlocks allow a pvops backend to replace the
- spinlock implementation with something virtualization-friendly
- (for example, block the virtual CPU rather than spinning).
- It has a minimal impact on native kernels and gives a nice performance
- benefit on paravirtualized KVM / Xen kernels.
- If you are unsure how to answer this question, answer Y.
- config X86_HV_CALLBACK_VECTOR
- def_bool n
- source "arch/x86/xen/Kconfig"
- config KVM_GUEST
- bool "KVM Guest support (including kvmclock)"
- depends on PARAVIRT
- select PARAVIRT_CLOCK
- select ARCH_CPUIDLE_HALTPOLL
- select X86_HV_CALLBACK_VECTOR
- default y
- help
- This option enables various optimizations for running under the KVM
- hypervisor. It includes a paravirtualized clock, so that instead
- of relying on a PIT (or probably other) emulation by the
- underlying device model, the host provides the guest with
- timing infrastructure such as time of day, and system time
- config ARCH_CPUIDLE_HALTPOLL
- def_bool n
- prompt "Disable host haltpoll when loading haltpoll driver"
- help
- If virtualized under KVM, disable host haltpoll.
- config PVH
- bool "Support for running PVH guests"
- help
- This option enables the PVH entry point for guest virtual machines
- as specified in the x86/HVM direct boot ABI.
- config PARAVIRT_TIME_ACCOUNTING
- bool "Paravirtual steal time accounting"
- depends on PARAVIRT
- help
- Select this option to enable fine granularity task steal time
- accounting. Time spent executing other tasks in parallel with
- the current vCPU is discounted from the vCPU power. To account for
- that, there can be a small performance impact.
- If in doubt, say N here.
- config PARAVIRT_CLOCK
- bool
- config JAILHOUSE_GUEST
- bool "Jailhouse non-root cell support"
- depends on X86_64 && PCI
- select X86_PM_TIMER
- help
- This option allows to run Linux as guest in a Jailhouse non-root
- cell. You can leave this option disabled if you only want to start
- Jailhouse and run Linux afterwards in the root cell.
- config ACRN_GUEST
- bool "ACRN Guest support"
- depends on X86_64
- select X86_HV_CALLBACK_VECTOR
- help
- This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
- a flexible, lightweight reference open-source hypervisor, built with
- real-time and safety-criticality in mind. It is built for embedded
- IOT with small footprint and real-time features. More details can be
- found in https://projectacrn.org/.
- config INTEL_TDX_GUEST
- bool "Intel TDX (Trust Domain Extensions) - Guest Support"
- depends on X86_64 && CPU_SUP_INTEL
- depends on X86_X2APIC
- depends on EFI_STUB
- select ARCH_HAS_CC_PLATFORM
- select X86_MEM_ENCRYPT
- select X86_MCE
- select UNACCEPTED_MEMORY
- help
- Support running as a guest under Intel TDX. Without this support,
- the guest kernel can not boot or run under TDX.
- TDX includes memory encryption and integrity capabilities
- which protect the confidentiality and integrity of guest
- memory contents and CPU state. TDX guests are protected from
- some attacks from the VMM.
- endif # HYPERVISOR_GUEST
- source "arch/x86/Kconfig.cpu"
- config HPET_TIMER
- def_bool X86_64
- prompt "HPET Timer Support" if X86_32
- help
- Use the IA-PC HPET (High Precision Event Timer) to manage
- time in preference to the PIT and RTC, if a HPET is
- present.
- HPET is the next generation timer replacing legacy 8254s.
- The HPET provides a stable time base on SMP
- systems, unlike the TSC, but it is more expensive to access,
- as it is off-chip. The interface used is documented
- in the HPET spec, revision 1.
- You can safely choose Y here. However, HPET will only be
- activated if the platform and the BIOS support this feature.
- Otherwise the 8254 will be used for timing services.
- Choose N to continue using the legacy 8254 timer.
- config HPET_EMULATE_RTC
- def_bool y
- depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
- # Mark as expert because too many people got it wrong.
- # The code disables itself when not needed.
- config DMI
- default y
- select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
- bool "Enable DMI scanning" if EXPERT
- help
- Enabled scanning of DMI to identify machine quirks. Say Y
- here unless you have verified that your setup is not
- affected by entries in the DMI blacklist. Required by PNP
- BIOS code.
- config GART_IOMMU
- bool "Old AMD GART IOMMU support"
- select IOMMU_HELPER
- select SWIOTLB
- depends on X86_64 && PCI && AMD_NB
- help
- Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
- GART based hardware IOMMUs.
- The GART supports full DMA access for devices with 32-bit access
- limitations, on systems with more than 3 GB. This is usually needed
- for USB, sound, many IDE/SATA chipsets and some other devices.
- Newer systems typically have a modern AMD IOMMU, supported via
- the CONFIG_AMD_IOMMU=y config option.
- In normal configurations this driver is only active when needed:
- there's more than 3 GB of memory and the system contains a
- 32-bit limited device.
- If unsure, say Y.
- config BOOT_VESA_SUPPORT
- bool
- help
- If true, at least one selected framebuffer driver can take advantage
- of VESA video modes set at an early boot stage via the vga= parameter.
- config MAXSMP
- bool "Enable Maximum number of SMP Processors and NUMA Nodes"
- depends on X86_64 && SMP && DEBUG_KERNEL
- select CPUMASK_OFFSTACK
- help
- Enable maximum number of CPUS and NUMA Nodes for this architecture.
- If unsure, say N.
- #
- # The maximum number of CPUs supported:
- #
- # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
- # and which can be configured interactively in the
- # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
- #
- # The ranges are different on 32-bit and 64-bit kernels, depending on
- # hardware capabilities and scalability features of the kernel.
- #
- # ( If MAXSMP is enabled we just use the highest possible value and disable
- # interactive configuration. )
- #
- config NR_CPUS_RANGE_BEGIN
- int
- default NR_CPUS_RANGE_END if MAXSMP
- default 1 if !SMP
- default 2
- config NR_CPUS_RANGE_END
- int
- depends on X86_32
- default 64 if SMP && X86_BIGSMP
- default 8 if SMP && !X86_BIGSMP
- default 1 if !SMP
- config NR_CPUS_RANGE_END
- int
- depends on X86_64
- default 8192 if SMP && CPUMASK_OFFSTACK
- default 512 if SMP && !CPUMASK_OFFSTACK
- default 1 if !SMP
- config NR_CPUS_DEFAULT
- int
- depends on X86_32
- default 32 if X86_BIGSMP
- default 8 if SMP
- default 1 if !SMP
- config NR_CPUS_DEFAULT
- int
- depends on X86_64
- default 8192 if MAXSMP
- default 64 if SMP
- default 1 if !SMP
- config NR_CPUS
- int "Maximum number of CPUs" if SMP && !MAXSMP
- range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
- default NR_CPUS_DEFAULT
- help
- This allows you to specify the maximum number of CPUs which this
- kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
- supported value is 8192, otherwise the maximum value is 512. The
- minimum value which makes sense is 2.
- This is purely to save memory: each supported CPU adds about 8KB
- to the kernel image.
- config SCHED_CLUSTER
- bool "Cluster scheduler support"
- depends on SMP
- default y
- help
- Cluster scheduler support improves the CPU scheduler's decision
- making when dealing with machines that have clusters of CPUs.
- Cluster usually means a couple of CPUs which are placed closely
- by sharing mid-level caches, last-level cache tags or internal
- busses.
- config SCHED_SMT
- def_bool y if SMP
- config SCHED_MC
- def_bool y
- prompt "Multi-core scheduler support"
- depends on SMP
- help
- Multi-core scheduler support improves the CPU scheduler's decision
- making when dealing with multi-core CPU chips at a cost of slightly
- increased overhead in some places. If unsure say N here.
- config SCHED_MC_PRIO
- bool "CPU core priorities scheduler support"
- depends on SCHED_MC
- select X86_INTEL_PSTATE if CPU_SUP_INTEL
- select X86_AMD_PSTATE if CPU_SUP_AMD && ACPI
- select CPU_FREQ
- default y
- help
- Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
- core ordering determined at manufacturing time, which allows
- certain cores to reach higher turbo frequencies (when running
- single threaded workloads) than others.
- Enabling this kernel feature teaches the scheduler about
- the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
- scheduler's CPU selection logic accordingly, so that higher
- overall system performance can be achieved.
- This feature will have no effect on CPUs without this feature.
- If unsure say Y here.
- config UP_LATE_INIT
- def_bool y
- depends on !SMP && X86_LOCAL_APIC
- config X86_UP_APIC
- bool "Local APIC support on uniprocessors" if !PCI_MSI
- default PCI_MSI
- depends on X86_32 && !SMP && !X86_32_NON_STANDARD
- help
- A local APIC (Advanced Programmable Interrupt Controller) is an
- integrated interrupt controller in the CPU. If you have a single-CPU
- system which has a processor with a local APIC, you can say Y here to
- enable and use it. If you say Y here even though your machine doesn't
- have a local APIC, then the kernel will still run with no slowdown at
- all. The local APIC supports CPU-generated self-interrupts (timer,
- performance counters), and the NMI watchdog which detects hard
- lockups.
- config X86_UP_IOAPIC
- bool "IO-APIC support on uniprocessors"
- depends on X86_UP_APIC
- help
- An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
- SMP-capable replacement for PC-style interrupt controllers. Most
- SMP systems and many recent uniprocessor systems have one.
- If you have a single-CPU system with an IO-APIC, you can say Y here
- to use it. If you say Y here even though your machine doesn't have
- an IO-APIC, then the kernel will still run with no slowdown at all.
- config X86_LOCAL_APIC
- def_bool y
- depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
- select IRQ_DOMAIN_HIERARCHY
- config ACPI_MADT_WAKEUP
- def_bool y
- depends on X86_64
- depends on ACPI
- depends on SMP
- depends on X86_LOCAL_APIC
- config X86_IO_APIC
- def_bool y
- depends on X86_LOCAL_APIC || X86_UP_IOAPIC
- config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
- bool "Reroute for broken boot IRQs"
- depends on X86_IO_APIC
- help
- This option enables a workaround that fixes a source of
- spurious interrupts. This is recommended when threaded
- interrupt handling is used on systems where the generation of
- superfluous "boot interrupts" cannot be disabled.
- Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
- entry in the chipset's IO-APIC is masked (as, e.g. the RT
- kernel does during interrupt handling). On chipsets where this
- boot IRQ generation cannot be disabled, this workaround keeps
- the original IRQ line masked so that only the equivalent "boot
- IRQ" is delivered to the CPUs. The workaround also tells the
- kernel to set up the IRQ handler on the boot IRQ line. In this
- way only one interrupt is delivered to the kernel. Otherwise
- the spurious second interrupt may cause the kernel to bring
- down (vital) interrupt lines.
- Only affects "broken" chipsets. Interrupt sharing may be
- increased on these systems.
- config X86_MCE
- bool "Machine Check / overheating reporting"
- select GENERIC_ALLOCATOR
- default y
- help
- Machine Check support allows the processor to notify the
- kernel if it detects a problem (e.g. overheating, data corruption).
- The action the kernel takes depends on the severity of the problem,
- ranging from warning messages to halting the machine.
- config X86_MCELOG_LEGACY
- bool "Support for deprecated /dev/mcelog character device"
- depends on X86_MCE
- help
- Enable support for /dev/mcelog which is needed by the old mcelog
- userspace logging daemon. Consider switching to the new generation
- rasdaemon solution.
- config X86_MCE_INTEL
- def_bool y
- prompt "Intel MCE features"
- depends on X86_MCE && X86_LOCAL_APIC
- help
- Additional support for intel specific MCE features such as
- the thermal monitor.
- config X86_MCE_AMD
- def_bool y
- prompt "AMD MCE features"
- depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
- help
- Additional support for AMD specific MCE features such as
- the DRAM Error Threshold.
- config X86_ANCIENT_MCE
- bool "Support for old Pentium 5 / WinChip machine checks"
- depends on X86_32 && X86_MCE
- help
- Include support for machine check handling on old Pentium 5 or WinChip
- systems. These typically need to be enabled explicitly on the command
- line.
- config X86_MCE_THRESHOLD
- depends on X86_MCE_AMD || X86_MCE_INTEL
- def_bool y
- config X86_MCE_INJECT
- depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
- tristate "Machine check injector support"
- help
- Provide support for injecting machine checks for testing purposes.
- If you don't know what a machine check is and you don't do kernel
- QA it is safe to say n.
- source "arch/x86/events/Kconfig"
- config X86_LEGACY_VM86
- bool "Legacy VM86 support"
- depends on X86_32
- help
- This option allows user programs to put the CPU into V8086
- mode, which is an 80286-era approximation of 16-bit real mode.
- Some very old versions of X and/or vbetool require this option
- for user mode setting. Similarly, DOSEMU will use it if
- available to accelerate real mode DOS programs. However, any
- recent version of DOSEMU, X, or vbetool should be fully
- functional even without kernel VM86 support, as they will all
- fall back to software emulation. Nevertheless, if you are using
- a 16-bit DOS program where 16-bit performance matters, vm86
- mode might be faster than emulation and you might want to
- enable this option.
- Note that any app that works on a 64-bit kernel is unlikely to
- need this option, as 64-bit kernels don't, and can't, support
- V8086 mode. This option is also unrelated to 16-bit protected
- mode and is not needed to run most 16-bit programs under Wine.
- Enabling this option increases the complexity of the kernel
- and slows down exception handling a tiny bit.
- If unsure, say N here.
- config VM86
- bool
- default X86_LEGACY_VM86
- config X86_16BIT
- bool "Enable support for 16-bit segments" if EXPERT
- default y
- depends on MODIFY_LDT_SYSCALL
- help
- This option is required by programs like Wine to run 16-bit
- protected mode legacy code on x86 processors. Disabling
- this option saves about 300 bytes on i386, or around 6K text
- plus 16K runtime memory on x86-64,
- config X86_ESPFIX32
- def_bool y
- depends on X86_16BIT && X86_32
- config X86_ESPFIX64
- def_bool y
- depends on X86_16BIT && X86_64
- config X86_VSYSCALL_EMULATION
- bool "Enable vsyscall emulation" if EXPERT
- default y
- depends on X86_64
- help
- This enables emulation of the legacy vsyscall page. Disabling
- it is roughly equivalent to booting with vsyscall=none, except
- that it will also disable the helpful warning if a program
- tries to use a vsyscall. With this option set to N, offending
- programs will just segfault, citing addresses of the form
- 0xffffffffff600?00.
- This option is required by many programs built before 2013, and
- care should be used even with newer programs if set to N.
- Disabling this option saves about 7K of kernel size and
- possibly 4K of additional runtime pagetable memory.
- config X86_IOPL_IOPERM
- bool "IOPERM and IOPL Emulation"
- default y
- help
- This enables the ioperm() and iopl() syscalls which are necessary
- for legacy applications.
- Legacy IOPL support is an overbroad mechanism which allows user
- space aside of accessing all 65536 I/O ports also to disable
- interrupts. To gain this access the caller needs CAP_SYS_RAWIO
- capabilities and permission from potentially active security
- modules.
- The emulation restricts the functionality of the syscall to
- only allowing the full range I/O port access, but prevents the
- ability to disable interrupts from user space which would be
- granted if the hardware IOPL mechanism would be used.
- config TOSHIBA
- tristate "Toshiba Laptop support"
- depends on X86_32
- help
- This adds a driver to safely access the System Management Mode of
- the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
- not work on models with a Phoenix BIOS. The System Management Mode
- is used to set the BIOS and power saving options on Toshiba portables.
- For information on utilities to make use of this driver see the
- Toshiba Linux utilities web site at:
- <http://www.buzzard.org.uk/toshiba/>.
- Say Y if you intend to run this kernel on a Toshiba portable.
- Say N otherwise.
- config X86_REBOOTFIXUPS
- bool "Enable X86 board specific fixups for reboot"
- depends on X86_32
- help
- This enables chipset and/or board specific fixups to be done
- in order to get reboot to work correctly. This is only needed on
- some combinations of hardware and BIOS. The symptom, for which
- this config is intended, is when reboot ends with a stalled/hung
- system.
- Currently, the only fixup is for the Geode machines using
- CS5530A and CS5536 chipsets and the RDC R-321x SoC.
- Say Y if you want to enable the fixup. Currently, it's safe to
- enable this option even if you don't need it.
- Say N otherwise.
- config MICROCODE
- def_bool y
- depends on CPU_SUP_AMD || CPU_SUP_INTEL
- config MICROCODE_INITRD32
- def_bool y
- depends on MICROCODE && X86_32 && BLK_DEV_INITRD
- config MICROCODE_LATE_LOADING
- bool "Late microcode loading (DANGEROUS)"
- default n
- depends on MICROCODE && SMP
- help
- Loading microcode late, when the system is up and executing instructions
- is a tricky business and should be avoided if possible. Just the sequence
- of synchronizing all cores and SMT threads is one fragile dance which does
- not guarantee that cores might not softlock after the loading. Therefore,
- use this at your own risk. Late loading taints the kernel unless the
- microcode header indicates that it is safe for late loading via the
- minimal revision check. This minimal revision check can be enforced on
- the kernel command line with "microcode.minrev=Y".
- config MICROCODE_LATE_FORCE_MINREV
- bool "Enforce late microcode loading minimal revision check"
- default n
- depends on MICROCODE_LATE_LOADING
- help
- To prevent that users load microcode late which modifies already
- in use features, newer microcode patches have a minimum revision field
- in the microcode header, which tells the kernel which minimum
- revision must be active in the CPU to safely load that new microcode
- late into the running system. If disabled the check will not
- be enforced but the kernel will be tainted when the minimal
- revision check fails.
- This minimal revision check can also be controlled via the
- "microcode.minrev" parameter on the kernel command line.
- If unsure say Y.
- config X86_MSR
- tristate "/dev/cpu/*/msr - Model-specific register support"
- help
- This device gives privileged processes access to the x86
- Model-Specific Registers (MSRs). It is a character device with
- major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
- MSR accesses are directed to a specific CPU on multi-processor
- systems.
- config X86_CPUID
- tristate "/dev/cpu/*/cpuid - CPU information support"
- help
- This device gives processes access to the x86 CPUID instruction to
- be executed on a specific processor. It is a character device
- with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
- /dev/cpu/31/cpuid.
- choice
- prompt "High Memory Support"
- default HIGHMEM4G
- depends on X86_32
- config NOHIGHMEM
- bool "off"
- help
- Linux can use up to 64 Gigabytes of physical memory on x86 systems.
- However, the address space of 32-bit x86 processors is only 4
- Gigabytes large. That means that, if you have a large amount of
- physical memory, not all of it can be "permanently mapped" by the
- kernel. The physical memory that's not permanently mapped is called
- "high memory".
- If you are compiling a kernel which will never run on a machine with
- more than 1 Gigabyte total physical RAM, answer "off" here (default
- choice and suitable for most users). This will result in a "3GB/1GB"
- split: 3GB are mapped so that each process sees a 3GB virtual memory
- space and the remaining part of the 4GB virtual memory space is used
- by the kernel to permanently map as much physical memory as
- possible.
- If the machine has between 1 and 4 Gigabytes physical RAM, then
- answer "4GB" here.
- If more than 4 Gigabytes is used then answer "64GB" here. This
- selection turns Intel PAE (Physical Address Extension) mode on.
- PAE implements 3-level paging on IA32 processors. PAE is fully
- supported by Linux, PAE mode is implemented on all recent Intel
- processors (Pentium Pro and better). NOTE: If you say "64GB" here,
- then the kernel will not boot on CPUs that don't support PAE!
- The actual amount of total physical memory will either be
- auto detected or can be forced by using a kernel command line option
- such as "mem=256M". (Try "man bootparam" or see the documentation of
- your boot loader (lilo or loadlin) about how to pass options to the
- kernel at boot time.)
- If unsure, say "off".
- config HIGHMEM4G
- bool "4GB"
- help
- Select this if you have a 32-bit processor and between 1 and 4
- gigabytes of physical RAM.
- config HIGHMEM64G
- bool "64GB"
- depends on X86_HAVE_PAE
- select X86_PAE
- help
- Select this if you have a 32-bit processor and more than 4
- gigabytes of physical RAM.
- endchoice
- choice
- prompt "Memory split" if EXPERT
- default VMSPLIT_3G
- depends on X86_32
- help
- Select the desired split between kernel and user memory.
- If the address range available to the kernel is less than the
- physical memory installed, the remaining memory will be available
- as "high memory". Accessing high memory is a little more costly
- than low memory, as it needs to be mapped into the kernel first.
- Note that increasing the kernel address space limits the range
- available to user programs, making the address space there
- tighter. Selecting anything other than the default 3G/1G split
- will also likely make your kernel incompatible with binary-only
- kernel modules.
- If you are not absolutely sure what you are doing, leave this
- option alone!
- config VMSPLIT_3G
- bool "3G/1G user/kernel split"
- config VMSPLIT_3G_OPT
- depends on !X86_PAE
- bool "3G/1G user/kernel split (for full 1G low memory)"
- config VMSPLIT_2G
- bool "2G/2G user/kernel split"
- config VMSPLIT_2G_OPT
- depends on !X86_PAE
- bool "2G/2G user/kernel split (for full 2G low memory)"
- config VMSPLIT_1G
- bool "1G/3G user/kernel split"
- endchoice
- config PAGE_OFFSET
- hex
- default 0xB0000000 if VMSPLIT_3G_OPT
- default 0x80000000 if VMSPLIT_2G
- default 0x78000000 if VMSPLIT_2G_OPT
- default 0x40000000 if VMSPLIT_1G
- default 0xC0000000
- depends on X86_32
- config HIGHMEM
- def_bool y
- depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
- config X86_PAE
- bool "PAE (Physical Address Extension) Support"
- depends on X86_32 && X86_HAVE_PAE
- select PHYS_ADDR_T_64BIT
- select SWIOTLB
- help
- PAE is required for NX support, and furthermore enables
- larger swapspace support for non-overcommit purposes. It
- has the cost of more pagetable lookup overhead, and also
- consumes more pagetable space per process.
- config X86_5LEVEL
- bool "Enable 5-level page tables support"
- default y
- select DYNAMIC_MEMORY_LAYOUT
- select SPARSEMEM_VMEMMAP
- depends on X86_64
- help
- 5-level paging enables access to larger address space:
- up to 128 PiB of virtual address space and 4 PiB of
- physical address space.
- It will be supported by future Intel CPUs.
- A kernel with the option enabled can be booted on machines that
- support 4- or 5-level paging.
- See Documentation/arch/x86/x86_64/5level-paging.rst for more
- information.
- Say N if unsure.
- config X86_DIRECT_GBPAGES
- def_bool y
- depends on X86_64
- help
- Certain kernel features effectively disable kernel
- linear 1 GB mappings (even if the CPU otherwise
- supports them), so don't confuse the user by printing
- that we have them enabled.
- config X86_CPA_STATISTICS
- bool "Enable statistic for Change Page Attribute"
- depends on DEBUG_FS
- help
- Expose statistics about the Change Page Attribute mechanism, which
- helps to determine the effectiveness of preserving large and huge
- page mappings when mapping protections are changed.
- config X86_MEM_ENCRYPT
- select ARCH_HAS_FORCE_DMA_UNENCRYPTED
- select DYNAMIC_PHYSICAL_MASK
- def_bool n
- config AMD_MEM_ENCRYPT
- bool "AMD Secure Memory Encryption (SME) support"
- depends on X86_64 && CPU_SUP_AMD
- depends on EFI_STUB
- select DMA_COHERENT_POOL
- select ARCH_USE_MEMREMAP_PROT
- select INSTRUCTION_DECODER
- select ARCH_HAS_CC_PLATFORM
- select X86_MEM_ENCRYPT
- select UNACCEPTED_MEMORY
- help
- Say yes to enable support for the encryption of system memory.
- This requires an AMD processor that supports Secure Memory
- Encryption (SME).
- # Common NUMA Features
- config NUMA
- bool "NUMA Memory Allocation and Scheduler Support"
- depends on SMP
- depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
- default y if X86_BIGSMP
- select USE_PERCPU_NUMA_NODE_ID
- select OF_NUMA if OF
- help
- Enable NUMA (Non-Uniform Memory Access) support.
- The kernel will try to allocate memory used by a CPU on the
- local memory controller of the CPU and add some more
- NUMA awareness to the kernel.
- For 64-bit this is recommended if the system is Intel Core i7
- (or later), AMD Opteron, or EM64T NUMA.
- For 32-bit this is only needed if you boot a 32-bit
- kernel on a 64-bit NUMA platform.
- Otherwise, you should say N.
- config AMD_NUMA
- def_bool y
- prompt "Old style AMD Opteron NUMA detection"
- depends on X86_64 && NUMA && PCI
- help
- Enable AMD NUMA node topology detection. You should say Y here if
- you have a multi processor AMD system. This uses an old method to
- read the NUMA configuration directly from the builtin Northbridge
- of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
- which also takes priority if both are compiled in.
- config X86_64_ACPI_NUMA
- def_bool y
- prompt "ACPI NUMA detection"
- depends on X86_64 && NUMA && ACPI && PCI
- select ACPI_NUMA
- help
- Enable ACPI SRAT based node topology detection.
- config NODES_SHIFT
- int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
- range 1 10
- default "10" if MAXSMP
- default "6" if X86_64
- default "3"
- depends on NUMA
- help
- Specify the maximum number of NUMA Nodes available on the target
- system. Increases memory reserved to accommodate various tables.
- config ARCH_FLATMEM_ENABLE
- def_bool y
- depends on X86_32 && !NUMA
- config ARCH_SPARSEMEM_ENABLE
- def_bool y
- depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
- select SPARSEMEM_STATIC if X86_32
- select SPARSEMEM_VMEMMAP_ENABLE if X86_64
- config ARCH_SPARSEMEM_DEFAULT
- def_bool X86_64 || (NUMA && X86_32)
- config ARCH_SELECT_MEMORY_MODEL
- def_bool y
- depends on ARCH_SPARSEMEM_ENABLE && ARCH_FLATMEM_ENABLE
- config ARCH_MEMORY_PROBE
- bool "Enable sysfs memory/probe interface"
- depends on MEMORY_HOTPLUG
- help
- This option enables a sysfs memory/probe interface for testing.
- See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
- If you are unsure how to answer this question, answer N.
- config ARCH_PROC_KCORE_TEXT
- def_bool y
- depends on X86_64 && PROC_KCORE
- config ILLEGAL_POINTER_VALUE
- hex
- default 0 if X86_32
- default 0xdead000000000000 if X86_64
- config X86_PMEM_LEGACY_DEVICE
- bool
- config X86_PMEM_LEGACY
- tristate "Support non-standard NVDIMMs and ADR protected memory"
- depends on PHYS_ADDR_T_64BIT
- depends on BLK_DEV
- select X86_PMEM_LEGACY_DEVICE
- select NUMA_KEEP_MEMINFO if NUMA
- select LIBNVDIMM
- help
- Treat memory marked using the non-standard e820 type of 12 as used
- by the Intel Sandy Bridge-EP reference BIOS as protected memory.
- The kernel will offer these regions to the 'pmem' driver so
- they can be used for persistent storage.
- Say Y if unsure.
- config HIGHPTE
- bool "Allocate 3rd-level pagetables from highmem"
- depends on HIGHMEM
- help
- The VM uses one page table entry for each page of physical memory.
- For systems with a lot of RAM, this can be wasteful of precious
- low memory. Setting this option will put user-space page table
- entries in high memory.
- config X86_CHECK_BIOS_CORRUPTION
- bool "Check for low memory corruption"
- help
- Periodically check for memory corruption in low memory, which
- is suspected to be caused by BIOS. Even when enabled in the
- configuration, it is disabled at runtime. Enable it by
- setting "memory_corruption_check=1" on the kernel command
- line. By default it scans the low 64k of memory every 60
- seconds; see the memory_corruption_check_size and
- memory_corruption_check_period parameters in
- Documentation/admin-guide/kernel-parameters.rst to adjust this.
- When enabled with the default parameters, this option has
- almost no overhead, as it reserves a relatively small amount
- of memory and scans it infrequently. It both detects corruption
- and prevents it from affecting the running system.
- It is, however, intended as a diagnostic tool; if repeatable
- BIOS-originated corruption always affects the same memory,
- you can use memmap= to prevent the kernel from using that
- memory.
- config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
- bool "Set the default setting of memory_corruption_check"
- depends on X86_CHECK_BIOS_CORRUPTION
- default y
- help
- Set whether the default state of memory_corruption_check is
- on or off.
- config MATH_EMULATION
- bool
- depends on MODIFY_LDT_SYSCALL
- prompt "Math emulation" if X86_32 && (M486SX || MELAN)
- help
- Linux can emulate a math coprocessor (used for floating point
- operations) if you don't have one. 486DX and Pentium processors have
- a math coprocessor built in, 486SX and 386 do not, unless you added
- a 487DX or 387, respectively. (The messages during boot time can
- give you some hints here ["man dmesg"].) Everyone needs either a
- coprocessor or this emulation.
- If you don't have a math coprocessor, you need to say Y here; if you
- say Y here even though you have a coprocessor, the coprocessor will
- be used nevertheless. (This behavior can be changed with the kernel
- command line option "no387", which comes handy if your coprocessor
- is broken. Try "man bootparam" or see the documentation of your boot
- loader (lilo or loadlin) about how to pass options to the kernel at
- boot time.) This means that it is a good idea to say Y here if you
- intend to use this kernel on different machines.
- More information about the internals of the Linux math coprocessor
- emulation can be found in <file:arch/x86/math-emu/README>.
- If you are not sure, say Y; apart from resulting in a 66 KB bigger
- kernel, it won't hurt.
- config MTRR
- def_bool y
- prompt "MTRR (Memory Type Range Register) support" if EXPERT
- help
- On Intel P6 family processors (Pentium Pro, Pentium II and later)
- the Memory Type Range Registers (MTRRs) may be used to control
- processor access to memory ranges. This is most useful if you have
- a video (VGA) card on a PCI or AGP bus. Enabling write-combining
- allows bus write transfers to be combined into a larger transfer
- before bursting over the PCI/AGP bus. This can increase performance
- of image write operations 2.5 times or more. Saying Y here creates a
- /proc/mtrr file which may be used to manipulate your processor's
- MTRRs. Typically the X server should use this.
- This code has a reasonably generic interface so that similar
- control registers on other processors can be easily supported
- as well:
- The Cyrix 6x86, 6x86MX and M II processors have Address Range
- Registers (ARRs) which provide a similar functionality to MTRRs. For
- these, the ARRs are used to emulate the MTRRs.
- The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
- MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
- write-combining. All of these processors are supported by this code
- and it makes sense to say Y here if you have one of them.
- Saying Y here also fixes a problem with buggy SMP BIOSes which only
- set the MTRRs for the boot CPU and not for the secondary CPUs. This
- can lead to all sorts of problems, so it's good to say Y here.
- You can safely say Y even if your machine doesn't have MTRRs, you'll
- just add about 9 KB to your kernel.
- See <file:Documentation/arch/x86/mtrr.rst> for more information.
- config MTRR_SANITIZER
- def_bool y
- prompt "MTRR cleanup support"
- depends on MTRR
- help
- Convert MTRR layout from continuous to discrete, so X drivers can
- add writeback entries.
- Can be disabled with disable_mtrr_cleanup on the kernel command line.
- The largest mtrr entry size for a continuous block can be set with
- mtrr_chunk_size.
- If unsure, say Y.
- config MTRR_SANITIZER_ENABLE_DEFAULT
- int "MTRR cleanup enable value (0-1)"
- range 0 1
- default "0"
- depends on MTRR_SANITIZER
- help
- Enable mtrr cleanup default value
- config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
- int "MTRR cleanup spare reg num (0-7)"
- range 0 7
- default "1"
- depends on MTRR_SANITIZER
- help
- mtrr cleanup spare entries default, it can be changed via
- mtrr_spare_reg_nr=N on the kernel command line.
- config X86_PAT
- def_bool y
- prompt "x86 PAT support" if EXPERT
- depends on MTRR
- select ARCH_USES_PG_ARCH_2
- help
- Use PAT attributes to setup page level cache control.
- PATs are the modern equivalents of MTRRs and are much more
- flexible than MTRRs.
- Say N here if you see bootup problems (boot crash, boot hang,
- spontaneous reboots) or a non-working video driver.
- If unsure, say Y.
- config X86_UMIP
- def_bool y
- prompt "User Mode Instruction Prevention" if EXPERT
- help
- User Mode Instruction Prevention (UMIP) is a security feature in
- some x86 processors. If enabled, a general protection fault is
- issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
- executed in user mode. These instructions unnecessarily expose
- information about the hardware state.
- The vast majority of applications do not use these instructions.
- For the very few that do, software emulation is provided in
- specific cases in protected and virtual-8086 modes. Emulated
- results are dummy.
- config CC_HAS_IBT
- # GCC >= 9 and binutils >= 2.29
- # Retpoline check to work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93654
- # Clang/LLVM >= 14
- # https://github.com/llvm/llvm-project/commit/e0b89df2e0f0130881bf6c39bf31d7f6aac00e0f
- # https://github.com/llvm/llvm-project/commit/dfcf69770bc522b9e411c66454934a37c1f35332
- def_bool ((CC_IS_GCC && $(cc-option, -fcf-protection=branch -mindirect-branch-register)) || \
- (CC_IS_CLANG && CLANG_VERSION >= 140000)) && \
- $(as-instr,endbr64)
- config X86_CET
- def_bool n
- help
- CET features configured (Shadow stack or IBT)
- config X86_KERNEL_IBT
- prompt "Indirect Branch Tracking"
- def_bool y
- depends on X86_64 && CC_HAS_IBT && HAVE_OBJTOOL
- # https://github.com/llvm/llvm-project/commit/9d7001eba9c4cb311e03cd8cdc231f9e579f2d0f
- depends on !LD_IS_LLD || LLD_VERSION >= 140000
- select OBJTOOL
- select X86_CET
- help
- Build the kernel with support for Indirect Branch Tracking, a
- hardware support course-grain forward-edge Control Flow Integrity
- protection. It enforces that all indirect calls must land on
- an ENDBR instruction, as such, the compiler will instrument the
- code with them to make this happen.
- In addition to building the kernel with IBT, seal all functions that
- are not indirect call targets, avoiding them ever becoming one.
- This requires LTO like objtool runs and will slow down the build. It
- does significantly reduce the number of ENDBR instructions in the
- kernel image.
- config X86_INTEL_MEMORY_PROTECTION_KEYS
- prompt "Memory Protection Keys"
- def_bool y
- # Note: only available in 64-bit mode
- depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
- select ARCH_USES_HIGH_VMA_FLAGS
- select ARCH_HAS_PKEYS
- help
- Memory Protection Keys provides a mechanism for enforcing
- page-based protections, but without requiring modification of the
- page tables when an application changes protection domains.
- For details, see Documentation/core-api/protection-keys.rst
- If unsure, say y.
- config ARCH_PKEY_BITS
- int
- default 4
- choice
- prompt "TSX enable mode"
- depends on CPU_SUP_INTEL
- default X86_INTEL_TSX_MODE_OFF
- help
- Intel's TSX (Transactional Synchronization Extensions) feature
- allows to optimize locking protocols through lock elision which
- can lead to a noticeable performance boost.
- On the other hand it has been shown that TSX can be exploited
- to form side channel attacks (e.g. TAA) and chances are there
- will be more of those attacks discovered in the future.
- Therefore TSX is not enabled by default (aka tsx=off). An admin
- might override this decision by tsx=on the command line parameter.
- Even with TSX enabled, the kernel will attempt to enable the best
- possible TAA mitigation setting depending on the microcode available
- for the particular machine.
- This option allows to set the default tsx mode between tsx=on, =off
- and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
- details.
- Say off if not sure, auto if TSX is in use but it should be used on safe
- platforms or on if TSX is in use and the security aspect of tsx is not
- relevant.
- config X86_INTEL_TSX_MODE_OFF
- bool "off"
- help
- TSX is disabled if possible - equals to tsx=off command line parameter.
- config X86_INTEL_TSX_MODE_ON
- bool "on"
- help
- TSX is always enabled on TSX capable HW - equals the tsx=on command
- line parameter.
- config X86_INTEL_TSX_MODE_AUTO
- bool "auto"
- help
- TSX is enabled on TSX capable HW that is believed to be safe against
- side channel attacks- equals the tsx=auto command line parameter.
- endchoice
- config X86_SGX
- bool "Software Guard eXtensions (SGX)"
- depends on X86_64 && CPU_SUP_INTEL && X86_X2APIC
- depends on CRYPTO=y
- depends on CRYPTO_SHA256=y
- select MMU_NOTIFIER
- select NUMA_KEEP_MEMINFO if NUMA
- select XARRAY_MULTI
- help
- Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
- that can be used by applications to set aside private regions of code
- and data, referred to as enclaves. An enclave's private memory can
- only be accessed by code running within the enclave. Accesses from
- outside the enclave, including other enclaves, are disallowed by
- hardware.
- If unsure, say N.
- config X86_USER_SHADOW_STACK
- bool "X86 userspace shadow stack"
- depends on AS_WRUSS
- depends on X86_64
- select ARCH_USES_HIGH_VMA_FLAGS
- select X86_CET
- help
- Shadow stack protection is a hardware feature that detects function
- return address corruption. This helps mitigate ROP attacks.
- Applications must be enabled to use it, and old userspace does not
- get protection "for free".
- CPUs supporting shadow stacks were first released in 2020.
- See Documentation/arch/x86/shstk.rst for more information.
- If unsure, say N.
- config INTEL_TDX_HOST
- bool "Intel Trust Domain Extensions (TDX) host support"
- depends on CPU_SUP_INTEL
- depends on X86_64
- depends on KVM_INTEL
- depends on X86_X2APIC
- select ARCH_KEEP_MEMBLOCK
- depends on CONTIG_ALLOC
- depends on !KEXEC_CORE
- depends on X86_MCE
- help
- Intel Trust Domain Extensions (TDX) protects guest VMs from malicious
- host and certain physical attacks. This option enables necessary TDX
- support in the host kernel to run confidential VMs.
- If unsure, say N.
- config EFI
- bool "EFI runtime service support"
- depends on ACPI
- select UCS2_STRING
- select EFI_RUNTIME_WRAPPERS
- select ARCH_USE_MEMREMAP_PROT
- select EFI_RUNTIME_MAP if KEXEC_CORE
- help
- This enables the kernel to use EFI runtime services that are
- available (such as the EFI variable services).
- This option is only useful on systems that have EFI firmware.
- In addition, you should use the latest ELILO loader available
- at <http://elilo.sourceforge.net> in order to take advantage
- of EFI runtime services. However, even with this option, the
- resultant kernel should continue to boot on existing non-EFI
- platforms.
- config EFI_STUB
- bool "EFI stub support"
- depends on EFI
- select RELOCATABLE
- help
- This kernel feature allows a bzImage to be loaded directly
- by EFI firmware without the use of a bootloader.
- See Documentation/admin-guide/efi-stub.rst for more information.
- config EFI_HANDOVER_PROTOCOL
- bool "EFI handover protocol (DEPRECATED)"
- depends on EFI_STUB
- default y
- help
- Select this in order to include support for the deprecated EFI
- handover protocol, which defines alternative entry points into the
- EFI stub. This is a practice that has no basis in the UEFI
- specification, and requires a priori knowledge on the part of the
- bootloader about Linux/x86 specific ways of passing the command line
- and initrd, and where in memory those assets may be loaded.
- If in doubt, say Y. Even though the corresponding support is not
- present in upstream GRUB or other bootloaders, most distros build
- GRUB with numerous downstream patches applied, and may rely on the
- handover protocol as as result.
- config EFI_MIXED
- bool "EFI mixed-mode support"
- depends on EFI_STUB && X86_64
- help
- Enabling this feature allows a 64-bit kernel to be booted
- on a 32-bit firmware, provided that your CPU supports 64-bit
- mode.
- Note that it is not possible to boot a mixed-mode enabled
- kernel via the EFI boot stub - a bootloader that supports
- the EFI handover protocol must be used.
- If unsure, say N.
- config EFI_RUNTIME_MAP
- bool "Export EFI runtime maps to sysfs" if EXPERT
- depends on EFI
- help
- Export EFI runtime memory regions to /sys/firmware/efi/runtime-map.
- That memory map is required by the 2nd kernel to set up EFI virtual
- mappings after kexec, but can also be used for debugging purposes.
- See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
- source "kernel/Kconfig.hz"
- config ARCH_SUPPORTS_KEXEC
- def_bool y
- config ARCH_SUPPORTS_KEXEC_FILE
- def_bool X86_64
- config ARCH_SELECTS_KEXEC_FILE
- def_bool y
- depends on KEXEC_FILE
- select HAVE_IMA_KEXEC if IMA
- config ARCH_SUPPORTS_KEXEC_PURGATORY
- def_bool y
- config ARCH_SUPPORTS_KEXEC_SIG
- def_bool y
- config ARCH_SUPPORTS_KEXEC_SIG_FORCE
- def_bool y
- config ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
- def_bool y
- config ARCH_SUPPORTS_KEXEC_JUMP
- def_bool y
- config ARCH_SUPPORTS_CRASH_DUMP
- def_bool X86_64 || (X86_32 && HIGHMEM)
- config ARCH_DEFAULT_CRASH_DUMP
- def_bool y
- config ARCH_SUPPORTS_CRASH_HOTPLUG
- def_bool y
- config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
- def_bool CRASH_RESERVE
- config PHYSICAL_START
- hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
- default "0x1000000"
- help
- This gives the physical address where the kernel is loaded.
- If the kernel is not relocatable (CONFIG_RELOCATABLE=n) then bzImage
- will decompress itself to above physical address and run from there.
- Otherwise, bzImage will run from the address where it has been loaded
- by the boot loader. The only exception is if it is loaded below the
- above physical address, in which case it will relocate itself there.
- In normal kdump cases one does not have to set/change this option
- as now bzImage can be compiled as a completely relocatable image
- (CONFIG_RELOCATABLE=y) and be used to load and run from a different
- address. This option is mainly useful for the folks who don't want
- to use a bzImage for capturing the crash dump and want to use a
- vmlinux instead. vmlinux is not relocatable hence a kernel needs
- to be specifically compiled to run from a specific memory area
- (normally a reserved region) and this option comes handy.
- So if you are using bzImage for capturing the crash dump,
- leave the value here unchanged to 0x1000000 and set
- CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
- for capturing the crash dump change this value to start of
- the reserved region. In other words, it can be set based on
- the "X" value as specified in the "crashkernel=YM@XM"
- command line boot parameter passed to the panic-ed
- kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
- for more details about crash dumps.
- Usage of bzImage for capturing the crash dump is recommended as
- one does not have to build two kernels. Same kernel can be used
- as production kernel and capture kernel. Above option should have
- gone away after relocatable bzImage support is introduced. But it
- is present because there are users out there who continue to use
- vmlinux for dump capture. This option should go away down the
- line.
- Don't change this unless you know what you are doing.
- config RELOCATABLE
- bool "Build a relocatable kernel"
- default y
- help
- This builds a kernel image that retains relocation information
- so it can be loaded someplace besides the default 1MB.
- The relocations tend to make the kernel binary about 10% larger,
- but are discarded at runtime.
- One use is for the kexec on panic case where the recovery kernel
- must live at a different physical address than the primary
- kernel.
- Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
- it has been loaded at and the compile time physical address
- (CONFIG_PHYSICAL_START) is used as the minimum location.
- config RANDOMIZE_BASE
- bool "Randomize the address of the kernel image (KASLR)"
- depends on RELOCATABLE
- default y
- help
- In support of Kernel Address Space Layout Randomization (KASLR),
- this randomizes the physical address at which the kernel image
- is decompressed and the virtual address where the kernel
- image is mapped, as a security feature that deters exploit
- attempts relying on knowledge of the location of kernel
- code internals.
- On 64-bit, the kernel physical and virtual addresses are
- randomized separately. The physical address will be anywhere
- between 16MB and the top of physical memory (up to 64TB). The
- virtual address will be randomized from 16MB up to 1GB (9 bits
- of entropy). Note that this also reduces the memory space
- available to kernel modules from 1.5GB to 1GB.
- On 32-bit, the kernel physical and virtual addresses are
- randomized together. They will be randomized from 16MB up to
- 512MB (8 bits of entropy).
- Entropy is generated using the RDRAND instruction if it is
- supported. If RDTSC is supported, its value is mixed into
- the entropy pool as well. If neither RDRAND nor RDTSC are
- supported, then entropy is read from the i8254 timer. The
- usable entropy is limited by the kernel being built using
- 2GB addressing, and that PHYSICAL_ALIGN must be at a
- minimum of 2MB. As a result, only 10 bits of entropy are
- theoretically possible, but the implementations are further
- limited due to memory layouts.
- If unsure, say Y.
- # Relocation on x86 needs some additional build support
- config X86_NEED_RELOCS
- def_bool y
- depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
- config PHYSICAL_ALIGN
- hex "Alignment value to which kernel should be aligned"
- default "0x200000"
- range 0x2000 0x1000000 if X86_32
- range 0x200000 0x1000000 if X86_64
- help
- This value puts the alignment restrictions on physical address
- where kernel is loaded and run from. Kernel is compiled for an
- address which meets above alignment restriction.
- If bootloader loads the kernel at a non-aligned address and
- CONFIG_RELOCATABLE is set, kernel will move itself to nearest
- address aligned to above value and run from there.
- If bootloader loads the kernel at a non-aligned address and
- CONFIG_RELOCATABLE is not set, kernel will ignore the run time
- load address and decompress itself to the address it has been
- compiled for and run from there. The address for which kernel is
- compiled already meets above alignment restrictions. Hence the
- end result is that kernel runs from a physical address meeting
- above alignment restrictions.
- On 32-bit this value must be a multiple of 0x2000. On 64-bit
- this value must be a multiple of 0x200000.
- Don't change this unless you know what you are doing.
- config DYNAMIC_MEMORY_LAYOUT
- bool
- help
- This option makes base addresses of vmalloc and vmemmap as well as
- __PAGE_OFFSET movable during boot.
- config RANDOMIZE_MEMORY
- bool "Randomize the kernel memory sections"
- depends on X86_64
- depends on RANDOMIZE_BASE
- select DYNAMIC_MEMORY_LAYOUT
- default RANDOMIZE_BASE
- help
- Randomizes the base virtual address of kernel memory sections
- (physical memory mapping, vmalloc & vmemmap). This security feature
- makes exploits relying on predictable memory locations less reliable.
- The order of allocations remains unchanged. Entropy is generated in
- the same way as RANDOMIZE_BASE. Current implementation in the optimal
- configuration have in average 30,000 different possible virtual
- addresses for each memory section.
- If unsure, say Y.
- config RANDOMIZE_MEMORY_PHYSICAL_PADDING
- hex "Physical memory mapping padding" if EXPERT
- depends on RANDOMIZE_MEMORY
- default "0xa" if MEMORY_HOTPLUG
- default "0x0"
- range 0x1 0x40 if MEMORY_HOTPLUG
- range 0x0 0x40
- help
- Define the padding in terabytes added to the existing physical
- memory size during kernel memory randomization. It is useful
- for memory hotplug support but reduces the entropy available for
- address randomization.
- If unsure, leave at the default value.
- config ADDRESS_MASKING
- bool "Linear Address Masking support"
- depends on X86_64
- depends on COMPILE_TEST || !CPU_MITIGATIONS # wait for LASS
- help
- Linear Address Masking (LAM) modifies the checking that is applied
- to 64-bit linear addresses, allowing software to use of the
- untranslated address bits for metadata.
- The capability can be used for efficient address sanitizers (ASAN)
- implementation and for optimizations in JITs.
- config HOTPLUG_CPU
- def_bool y
- depends on SMP
- config COMPAT_VDSO
- def_bool n
- prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
- depends on COMPAT_32
- help
- Certain buggy versions of glibc will crash if they are
- presented with a 32-bit vDSO that is not mapped at the address
- indicated in its segment table.
- The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
- and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
- 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
- the only released version with the bug, but OpenSUSE 9
- contains a buggy "glibc 2.3.2".
- The symptom of the bug is that everything crashes on startup, saying:
- dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
- Saying Y here changes the default value of the vdso32 boot
- option from 1 to 0, which turns off the 32-bit vDSO entirely.
- This works around the glibc bug but hurts performance.
- If unsure, say N: if you are compiling your own kernel, you
- are unlikely to be using a buggy version of glibc.
- choice
- prompt "vsyscall table for legacy applications"
- depends on X86_64
- default LEGACY_VSYSCALL_XONLY
- help
- Legacy user code that does not know how to find the vDSO expects
- to be able to issue three syscalls by calling fixed addresses in
- kernel space. Since this location is not randomized with ASLR,
- it can be used to assist security vulnerability exploitation.
- This setting can be changed at boot time via the kernel command
- line parameter vsyscall=[emulate|xonly|none]. Emulate mode
- is deprecated and can only be enabled using the kernel command
- line.
- On a system with recent enough glibc (2.14 or newer) and no
- static binaries, you can say None without a performance penalty
- to improve security.
- If unsure, select "Emulate execution only".
- config LEGACY_VSYSCALL_XONLY
- bool "Emulate execution only"
- help
- The kernel traps and emulates calls into the fixed vsyscall
- address mapping and does not allow reads. This
- configuration is recommended when userspace might use the
- legacy vsyscall area but support for legacy binary
- instrumentation of legacy code is not needed. It mitigates
- certain uses of the vsyscall area as an ASLR-bypassing
- buffer.
- config LEGACY_VSYSCALL_NONE
- bool "None"
- help
- There will be no vsyscall mapping at all. This will
- eliminate any risk of ASLR bypass due to the vsyscall
- fixed address mapping. Attempts to use the vsyscalls
- will be reported to dmesg, so that either old or
- malicious userspace programs can be identified.
- endchoice
- config CMDLINE_BOOL
- bool "Built-in kernel command line"
- help
- Allow for specifying boot arguments to the kernel at
- build time. On some systems (e.g. embedded ones), it is
- necessary or convenient to provide some or all of the
- kernel boot arguments with the kernel itself (that is,
- to not rely on the boot loader to provide them.)
- To compile command line arguments into the kernel,
- set this option to 'Y', then fill in the
- boot arguments in CONFIG_CMDLINE.
- Systems with fully functional boot loaders (i.e. non-embedded)
- should leave this option set to 'N'.
- config CMDLINE
- string "Built-in kernel command string"
- depends on CMDLINE_BOOL
- default ""
- help
- Enter arguments here that should be compiled into the kernel
- image and used at boot time. If the boot loader provides a
- command line at boot time, it is appended to this string to
- form the full kernel command line, when the system boots.
- However, you can use the CONFIG_CMDLINE_OVERRIDE option to
- change this behavior.
- In most cases, the command line (whether built-in or provided
- by the boot loader) should specify the device for the root
- file system.
- config CMDLINE_OVERRIDE
- bool "Built-in command line overrides boot loader arguments"
- depends on CMDLINE_BOOL && CMDLINE != ""
- help
- Set this option to 'Y' to have the kernel ignore the boot loader
- command line, and use ONLY the built-in command line.
- This is used to work around broken boot loaders. This should
- be set to 'N' under normal conditions.
- config MODIFY_LDT_SYSCALL
- bool "Enable the LDT (local descriptor table)" if EXPERT
- default y
- help
- Linux can allow user programs to install a per-process x86
- Local Descriptor Table (LDT) using the modify_ldt(2) system
- call. This is required to run 16-bit or segmented code such as
- DOSEMU or some Wine programs. It is also used by some very old
- threading libraries.
- Enabling this feature adds a small amount of overhead to
- context switches and increases the low-level kernel attack
- surface. Disabling it removes the modify_ldt(2) system call.
- Saying 'N' here may make sense for embedded or server kernels.
- config STRICT_SIGALTSTACK_SIZE
- bool "Enforce strict size checking for sigaltstack"
- depends on DYNAMIC_SIGFRAME
- help
- For historical reasons MINSIGSTKSZ is a constant which became
- already too small with AVX512 support. Add a mechanism to
- enforce strict checking of the sigaltstack size against the
- real size of the FPU frame. This option enables the check
- by default. It can also be controlled via the kernel command
- line option 'strict_sas_size' independent of this config
- switch. Enabling it might break existing applications which
- allocate a too small sigaltstack but 'work' because they
- never get a signal delivered.
- Say 'N' unless you want to really enforce this check.
- config CFI_AUTO_DEFAULT
- bool "Attempt to use FineIBT by default at boot time"
- depends on FINEIBT
- default y
- help
- Attempt to use FineIBT by default at boot time. If enabled,
- this is the same as booting with "cfi=auto". If disabled,
- this is the same as booting with "cfi=kcfi".
- source "kernel/livepatch/Kconfig"
- endmenu
- config CC_HAS_NAMED_AS
- def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
- depends on CC_IS_GCC
- config CC_HAS_NAMED_AS_FIXED_SANITIZERS
- def_bool CC_IS_GCC && GCC_VERSION >= 130300
- config USE_X86_SEG_SUPPORT
- def_bool y
- depends on CC_HAS_NAMED_AS
- #
- # -fsanitize=kernel-address (KASAN) and -fsanitize=thread
- # (KCSAN) are incompatible with named address spaces with
- # GCC < 13.3 - see GCC PR sanitizer/111736.
- #
- depends on !(KASAN || KCSAN) || CC_HAS_NAMED_AS_FIXED_SANITIZERS
- config CC_HAS_SLS
- def_bool $(cc-option,-mharden-sls=all)
- config CC_HAS_RETURN_THUNK
- def_bool $(cc-option,-mfunction-return=thunk-extern)
- config CC_HAS_ENTRY_PADDING
- def_bool $(cc-option,-fpatchable-function-entry=16,16)
- config FUNCTION_PADDING_CFI
- int
- default 59 if FUNCTION_ALIGNMENT_64B
- default 27 if FUNCTION_ALIGNMENT_32B
- default 11 if FUNCTION_ALIGNMENT_16B
- default 3 if FUNCTION_ALIGNMENT_8B
- default 0
- # Basically: FUNCTION_ALIGNMENT - 5*CFI_CLANG
- # except Kconfig can't do arithmetic :/
- config FUNCTION_PADDING_BYTES
- int
- default FUNCTION_PADDING_CFI if CFI_CLANG
- default FUNCTION_ALIGNMENT
- config CALL_PADDING
- def_bool n
- depends on CC_HAS_ENTRY_PADDING && OBJTOOL
- select FUNCTION_ALIGNMENT_16B
- config FINEIBT
- def_bool y
- depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
- select CALL_PADDING
- config HAVE_CALL_THUNKS
- def_bool y
- depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
- config CALL_THUNKS
- def_bool n
- select CALL_PADDING
- config PREFIX_SYMBOLS
- def_bool y
- depends on CALL_PADDING && !CFI_CLANG
- menuconfig CPU_MITIGATIONS
- bool "Mitigations for CPU vulnerabilities"
- default y
- help
- Say Y here to enable options which enable mitigations for hardware
- vulnerabilities (usually related to speculative execution).
- Mitigations can be disabled or restricted to SMT systems at runtime
- via the "mitigations" kernel parameter.
- If you say N, all mitigations will be disabled. This CANNOT be
- overridden at runtime.
- Say 'Y', unless you really know what you are doing.
- if CPU_MITIGATIONS
- config MITIGATION_PAGE_TABLE_ISOLATION
- bool "Remove the kernel mapping in user mode"
- default y
- depends on (X86_64 || X86_PAE)
- help
- This feature reduces the number of hardware side channels by
- ensuring that the majority of kernel addresses are not mapped
- into userspace.
- See Documentation/arch/x86/pti.rst for more details.
- config MITIGATION_RETPOLINE
- bool "Avoid speculative indirect branches in kernel"
- select OBJTOOL if HAVE_OBJTOOL
- default y
- help
- Compile kernel with the retpoline compiler options to guard against
- kernel-to-user data leaks by avoiding speculative indirect
- branches. Requires a compiler with -mindirect-branch=thunk-extern
- support for full protection. The kernel may run slower.
- config MITIGATION_RETHUNK
- bool "Enable return-thunks"
- depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
- select OBJTOOL if HAVE_OBJTOOL
- default y if X86_64
- help
- Compile the kernel with the return-thunks compiler option to guard
- against kernel-to-user data leaks by avoiding return speculation.
- Requires a compiler with -mfunction-return=thunk-extern
- support for full protection. The kernel may run slower.
- config MITIGATION_UNRET_ENTRY
- bool "Enable UNRET on kernel entry"
- depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
- default y
- help
- Compile the kernel with support for the retbleed=unret mitigation.
- config MITIGATION_CALL_DEPTH_TRACKING
- bool "Mitigate RSB underflow with call depth tracking"
- depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
- select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
- select CALL_THUNKS
- default y
- help
- Compile the kernel with call depth tracking to mitigate the Intel
- SKL Return-Speculation-Buffer (RSB) underflow issue. The
- mitigation is off by default and needs to be enabled on the
- kernel command line via the retbleed=stuff option. For
- non-affected systems the overhead of this option is marginal as
- the call depth tracking is using run-time generated call thunks
- in a compiler generated padding area and call patching. This
- increases text size by ~5%. For non affected systems this space
- is unused. On affected SKL systems this results in a significant
- performance gain over the IBRS mitigation.
- config CALL_THUNKS_DEBUG
- bool "Enable call thunks and call depth tracking debugging"
- depends on MITIGATION_CALL_DEPTH_TRACKING
- select FUNCTION_ALIGNMENT_32B
- default n
- help
- Enable call/ret counters for imbalance detection and build in
- a noisy dmesg about callthunks generation and call patching for
- trouble shooting. The debug prints need to be enabled on the
- kernel command line with 'debug-callthunks'.
- Only enable this when you are debugging call thunks as this
- creates a noticeable runtime overhead. If unsure say N.
- config MITIGATION_IBPB_ENTRY
- bool "Enable IBPB on kernel entry"
- depends on CPU_SUP_AMD && X86_64
- default y
- help
- Compile the kernel with support for the retbleed=ibpb and
- spec_rstack_overflow={ibpb,ibpb-vmexit} mitigations.
- config MITIGATION_IBRS_ENTRY
- bool "Enable IBRS on kernel entry"
- depends on CPU_SUP_INTEL && X86_64
- default y
- help
- Compile the kernel with support for the spectre_v2=ibrs mitigation.
- This mitigates both spectre_v2 and retbleed at great cost to
- performance.
- config MITIGATION_SRSO
- bool "Mitigate speculative RAS overflow on AMD"
- depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
- default y
- help
- Enable the SRSO mitigation needed on AMD Zen1-4 machines.
- config MITIGATION_SLS
- bool "Mitigate Straight-Line-Speculation"
- depends on CC_HAS_SLS && X86_64
- select OBJTOOL if HAVE_OBJTOOL
- default n
- help
- Compile the kernel with straight-line-speculation options to guard
- against straight line speculation. The kernel image might be slightly
- larger.
- config MITIGATION_GDS
- bool "Mitigate Gather Data Sampling"
- depends on CPU_SUP_INTEL
- default y
- help
- Enable mitigation for Gather Data Sampling (GDS). GDS is a hardware
- vulnerability which allows unprivileged speculative access to data
- which was previously stored in vector registers. The attacker uses gather
- instructions to infer the stale vector register data.
- config MITIGATION_RFDS
- bool "RFDS Mitigation"
- depends on CPU_SUP_INTEL
- default y
- help
- Enable mitigation for Register File Data Sampling (RFDS) by default.
- RFDS is a hardware vulnerability which affects Intel Atom CPUs. It
- allows unprivileged speculative access to stale data previously
- stored in floating point, vector and integer registers.
- See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst>
- config MITIGATION_SPECTRE_BHI
- bool "Mitigate Spectre-BHB (Branch History Injection)"
- depends on CPU_SUP_INTEL
- default y
- help
- Enable BHI mitigations. BHI attacks are a form of Spectre V2 attacks
- where the branch history buffer is poisoned to speculatively steer
- indirect branches.
- See <file:Documentation/admin-guide/hw-vuln/spectre.rst>
- config MITIGATION_MDS
- bool "Mitigate Microarchitectural Data Sampling (MDS) hardware bug"
- depends on CPU_SUP_INTEL
- default y
- help
- Enable mitigation for Microarchitectural Data Sampling (MDS). MDS is
- a hardware vulnerability which allows unprivileged speculative access
- to data which is available in various CPU internal buffers.
- See also <file:Documentation/admin-guide/hw-vuln/mds.rst>
- config MITIGATION_TAA
- bool "Mitigate TSX Asynchronous Abort (TAA) hardware bug"
- depends on CPU_SUP_INTEL
- default y
- help
- Enable mitigation for TSX Asynchronous Abort (TAA). TAA is a hardware
- vulnerability that allows unprivileged speculative access to data
- which is available in various CPU internal buffers by using
- asynchronous aborts within an Intel TSX transactional region.
- See also <file:Documentation/admin-guide/hw-vuln/tsx_async_abort.rst>
- config MITIGATION_MMIO_STALE_DATA
- bool "Mitigate MMIO Stale Data hardware bug"
- depends on CPU_SUP_INTEL
- default y
- help
- Enable mitigation for MMIO Stale Data hardware bugs. Processor MMIO
- Stale Data Vulnerabilities are a class of memory-mapped I/O (MMIO)
- vulnerabilities that can expose data. The vulnerabilities require the
- attacker to have access to MMIO.
- See also
- <file:Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst>
- config MITIGATION_L1TF
- bool "Mitigate L1 Terminal Fault (L1TF) hardware bug"
- depends on CPU_SUP_INTEL
- default y
- help
- Mitigate L1 Terminal Fault (L1TF) hardware bug. L1 Terminal Fault is a
- hardware vulnerability which allows unprivileged speculative access to data
- available in the Level 1 Data Cache.
- See <file:Documentation/admin-guide/hw-vuln/l1tf.rst
- config MITIGATION_RETBLEED
- bool "Mitigate RETBleed hardware bug"
- depends on (CPU_SUP_INTEL && MITIGATION_SPECTRE_V2) || MITIGATION_UNRET_ENTRY || MITIGATION_IBPB_ENTRY
- default y
- help
- Enable mitigation for RETBleed (Arbitrary Speculative Code Execution
- with Return Instructions) vulnerability. RETBleed is a speculative
- execution attack which takes advantage of microarchitectural behavior
- in many modern microprocessors, similar to Spectre v2. An
- unprivileged attacker can use these flaws to bypass conventional
- memory security restrictions to gain read access to privileged memory
- that would otherwise be inaccessible.
- config MITIGATION_SPECTRE_V1
- bool "Mitigate SPECTRE V1 hardware bug"
- default y
- help
- Enable mitigation for Spectre V1 (Bounds Check Bypass). Spectre V1 is a
- class of side channel attacks that takes advantage of speculative
- execution that bypasses conditional branch instructions used for
- memory access bounds check.
- See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
- config MITIGATION_SPECTRE_V2
- bool "Mitigate SPECTRE V2 hardware bug"
- default y
- help
- Enable mitigation for Spectre V2 (Branch Target Injection). Spectre
- V2 is a class of side channel attacks that takes advantage of
- indirect branch predictors inside the processor. In Spectre variant 2
- attacks, the attacker can steer speculative indirect branches in the
- victim to gadget code by poisoning the branch target buffer of a CPU
- used for predicting indirect branch addresses.
- See also <file:Documentation/admin-guide/hw-vuln/spectre.rst>
- config MITIGATION_SRBDS
- bool "Mitigate Special Register Buffer Data Sampling (SRBDS) hardware bug"
- depends on CPU_SUP_INTEL
- default y
- help
- Enable mitigation for Special Register Buffer Data Sampling (SRBDS).
- SRBDS is a hardware vulnerability that allows Microarchitectural Data
- Sampling (MDS) techniques to infer values returned from special
- register accesses. An unprivileged user can extract values returned
- from RDRAND and RDSEED executed on another core or sibling thread
- using MDS techniques.
- See also
- <file:Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst>
- config MITIGATION_SSB
- bool "Mitigate Speculative Store Bypass (SSB) hardware bug"
- default y
- help
- Enable mitigation for Speculative Store Bypass (SSB). SSB is a
- hardware security vulnerability and its exploitation takes advantage
- of speculative execution in a similar way to the Meltdown and Spectre
- security vulnerabilities.
- endif
- config ARCH_HAS_ADD_PAGES
- def_bool y
- depends on ARCH_ENABLE_MEMORY_HOTPLUG
- menu "Power management and ACPI options"
- config ARCH_HIBERNATION_HEADER
- def_bool y
- depends on HIBERNATION
- source "kernel/power/Kconfig"
- source "drivers/acpi/Kconfig"
- config X86_APM_BOOT
- def_bool y
- depends on APM
- menuconfig APM
- tristate "APM (Advanced Power Management) BIOS support"
- depends on X86_32 && PM_SLEEP
- help
- APM is a BIOS specification for saving power using several different
- techniques. This is mostly useful for battery powered laptops with
- APM compliant BIOSes. If you say Y here, the system time will be
- reset after a RESUME operation, the /proc/apm device will provide
- battery status information, and user-space programs will receive
- notification of APM "events" (e.g. battery status change).
- If you select "Y" here, you can disable actual use of the APM
- BIOS by passing the "apm=off" option to the kernel at boot time.
- Note that the APM support is almost completely disabled for
- machines with more than one CPU.
- In order to use APM, you will need supporting software. For location
- and more information, read <file:Documentation/power/apm-acpi.rst>
- and the Battery Powered Linux mini-HOWTO, available from
- <http://www.tldp.org/docs.html#howto>.
- This driver does not spin down disk drives (see the hdparm(8)
- manpage ("man 8 hdparm") for that), and it doesn't turn off
- VESA-compliant "green" monitors.
- This driver does not support the TI 4000M TravelMate and the ACER
- 486/DX4/75 because they don't have compliant BIOSes. Many "green"
- desktop machines also don't have compliant BIOSes, and this driver
- may cause those machines to panic during the boot phase.
- Generally, if you don't have a battery in your machine, there isn't
- much point in using this driver and you should say N. If you get
- random kernel OOPSes or reboots that don't seem to be related to
- anything, try disabling/enabling this option (or disabling/enabling
- APM in your BIOS).
- Some other things you should try when experiencing seemingly random,
- "weird" problems:
- 1) make sure that you have enough swap space and that it is
- enabled.
- 2) pass the "idle=poll" option to the kernel
- 3) switch on floating point emulation in the kernel and pass
- the "no387" option to the kernel
- 4) pass the "floppy=nodma" option to the kernel
- 5) pass the "mem=4M" option to the kernel (thereby disabling
- all but the first 4 MB of RAM)
- 6) make sure that the CPU is not over clocked.
- 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
- 8) disable the cache from your BIOS settings
- 9) install a fan for the video card or exchange video RAM
- 10) install a better fan for the CPU
- 11) exchange RAM chips
- 12) exchange the motherboard.
- To compile this driver as a module, choose M here: the
- module will be called apm.
- if APM
- config APM_IGNORE_USER_SUSPEND
- bool "Ignore USER SUSPEND"
- help
- This option will ignore USER SUSPEND requests. On machines with a
- compliant APM BIOS, you want to say N. However, on the NEC Versa M
- series notebooks, it is necessary to say Y because of a BIOS bug.
- config APM_DO_ENABLE
- bool "Enable PM at boot time"
- help
- Enable APM features at boot time. From page 36 of the APM BIOS
- specification: "When disabled, the APM BIOS does not automatically
- power manage devices, enter the Standby State, enter the Suspend
- State, or take power saving steps in response to CPU Idle calls."
- This driver will make CPU Idle calls when Linux is idle (unless this
- feature is turned off -- see "Do CPU IDLE calls", below). This
- should always save battery power, but more complicated APM features
- will be dependent on your BIOS implementation. You may need to turn
- this option off if your computer hangs at boot time when using APM
- support, or if it beeps continuously instead of suspending. Turn
- this off if you have a NEC UltraLite Versa 33/C or a Toshiba
- T400CDT. This is off by default since most machines do fine without
- this feature.
- config APM_CPU_IDLE
- depends on CPU_IDLE
- bool "Make CPU Idle calls when idle"
- help
- Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
- On some machines, this can activate improved power savings, such as
- a slowed CPU clock rate, when the machine is idle. These idle calls
- are made after the idle loop has run for some length of time (e.g.,
- 333 mS). On some machines, this will cause a hang at boot time or
- whenever the CPU becomes idle. (On machines with more than one CPU,
- this option does nothing.)
- config APM_DISPLAY_BLANK
- bool "Enable console blanking using APM"
- help
- Enable console blanking using the APM. Some laptops can use this to
- turn off the LCD backlight when the screen blanker of the Linux
- virtual console blanks the screen. Note that this is only used by
- the virtual console screen blanker, and won't turn off the backlight
- when using the X Window system. This also doesn't have anything to
- do with your VESA-compliant power-saving monitor. Further, this
- option doesn't work for all laptops -- it might not turn off your
- backlight at all, or it might print a lot of errors to the console,
- especially if you are using gpm.
- config APM_ALLOW_INTS
- bool "Allow interrupts during APM BIOS calls"
- help
- Normally we disable external interrupts while we are making calls to
- the APM BIOS as a measure to lessen the effects of a badly behaving
- BIOS implementation. The BIOS should reenable interrupts if it
- needs to. Unfortunately, some BIOSes do not -- especially those in
- many of the newer IBM Thinkpads. If you experience hangs when you
- suspend, try setting this to Y. Otherwise, say N.
- endif # APM
- source "drivers/cpufreq/Kconfig"
- source "drivers/cpuidle/Kconfig"
- source "drivers/idle/Kconfig"
- endmenu
- menu "Bus options (PCI etc.)"
- choice
- prompt "PCI access mode"
- depends on X86_32 && PCI
- default PCI_GOANY
- help
- On PCI systems, the BIOS can be used to detect the PCI devices and
- determine their configuration. However, some old PCI motherboards
- have BIOS bugs and may crash if this is done. Also, some embedded
- PCI-based systems don't have any BIOS at all. Linux can also try to
- detect the PCI hardware directly without using the BIOS.
- With this option, you can specify how Linux should detect the
- PCI devices. If you choose "BIOS", the BIOS will be used,
- if you choose "Direct", the BIOS won't be used, and if you
- choose "MMConfig", then PCI Express MMCONFIG will be used.
- If you choose "Any", the kernel will try MMCONFIG, then the
- direct access method and falls back to the BIOS if that doesn't
- work. If unsure, go with the default, which is "Any".
- config PCI_GOBIOS
- bool "BIOS"
- config PCI_GOMMCONFIG
- bool "MMConfig"
- config PCI_GODIRECT
- bool "Direct"
- config PCI_GOOLPC
- bool "OLPC XO-1"
- depends on OLPC
- config PCI_GOANY
- bool "Any"
- endchoice
- config PCI_BIOS
- def_bool y
- depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
- # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
- config PCI_DIRECT
- def_bool y
- depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
- config PCI_MMCONFIG
- bool "Support mmconfig PCI config space access" if X86_64
- default y
- depends on PCI && (ACPI || JAILHOUSE_GUEST)
- depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
- config PCI_OLPC
- def_bool y
- depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
- config PCI_XEN
- def_bool y
- depends on PCI && XEN
- config MMCONF_FAM10H
- def_bool y
- depends on X86_64 && PCI_MMCONFIG && ACPI
- config PCI_CNB20LE_QUIRK
- bool "Read CNB20LE Host Bridge Windows" if EXPERT
- depends on PCI
- help
- Read the PCI windows out of the CNB20LE host bridge. This allows
- PCI hotplug to work on systems with the CNB20LE chipset which do
- not have ACPI.
- There's no public spec for this chipset, and this functionality
- is known to be incomplete.
- You should say N unless you know you need this.
- config ISA_BUS
- bool "ISA bus support on modern systems" if EXPERT
- help
- Expose ISA bus device drivers and options available for selection and
- configuration. Enable this option if your target machine has an ISA
- bus. ISA is an older system, displaced by PCI and newer bus
- architectures -- if your target machine is modern, it probably does
- not have an ISA bus.
- If unsure, say N.
- # x86_64 have no ISA slots, but can have ISA-style DMA.
- config ISA_DMA_API
- bool "ISA-style DMA support" if (X86_64 && EXPERT)
- default y
- help
- Enables ISA-style DMA support for devices requiring such controllers.
- If unsure, say Y.
- if X86_32
- config ISA
- bool "ISA support"
- help
- Find out whether you have ISA slots on your motherboard. ISA is the
- name of a bus system, i.e. the way the CPU talks to the other stuff
- inside your box. Other bus systems are PCI, EISA, MicroChannel
- (MCA) or VESA. ISA is an older system, now being displaced by PCI;
- newer boards don't support it. If you have ISA, say Y, otherwise N.
- config SCx200
- tristate "NatSemi SCx200 support"
- help
- This provides basic support for National Semiconductor's
- (now AMD's) Geode processors. The driver probes for the
- PCI-IDs of several on-chip devices, so its a good dependency
- for other scx200_* drivers.
- If compiled as a module, the driver is named scx200.
- config SCx200HR_TIMER
- tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
- depends on SCx200
- default y
- help
- This driver provides a clocksource built upon the on-chip
- 27MHz high-resolution timer. Its also a workaround for
- NSC Geode SC-1100's buggy TSC, which loses time when the
- processor goes idle (as is done by the scheduler). The
- other workaround is idle=poll boot option.
- config OLPC
- bool "One Laptop Per Child support"
- depends on !X86_PAE
- select GPIOLIB
- select OF
- select OF_PROMTREE
- select IRQ_DOMAIN
- select OLPC_EC
- help
- Add support for detecting the unique features of the OLPC
- XO hardware.
- config OLPC_XO1_PM
- bool "OLPC XO-1 Power Management"
- depends on OLPC && MFD_CS5535=y && PM_SLEEP
- help
- Add support for poweroff and suspend of the OLPC XO-1 laptop.
- config OLPC_XO1_RTC
- bool "OLPC XO-1 Real Time Clock"
- depends on OLPC_XO1_PM && RTC_DRV_CMOS
- help
- Add support for the XO-1 real time clock, which can be used as a
- programmable wakeup source.
- config OLPC_XO1_SCI
- bool "OLPC XO-1 SCI extras"
- depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
- depends on INPUT=y
- select POWER_SUPPLY
- help
- Add support for SCI-based features of the OLPC XO-1 laptop:
- - EC-driven system wakeups
- - Power button
- - Ebook switch
- - Lid switch
- - AC adapter status updates
- - Battery status updates
- config OLPC_XO15_SCI
- bool "OLPC XO-1.5 SCI extras"
- depends on OLPC && ACPI
- select POWER_SUPPLY
- help
- Add support for SCI-based features of the OLPC XO-1.5 laptop:
- - EC-driven system wakeups
- - AC adapter status updates
- - Battery status updates
- config GEODE_COMMON
- bool
- config ALIX
- bool "PCEngines ALIX System Support (LED setup)"
- select GPIOLIB
- select GEODE_COMMON
- help
- This option enables system support for the PCEngines ALIX.
- At present this just sets up LEDs for GPIO control on
- ALIX2/3/6 boards. However, other system specific setup should
- get added here.
- Note: You must still enable the drivers for GPIO and LED support
- (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
- Note: You have to set alix.force=1 for boards with Award BIOS.
- config NET5501
- bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
- select GPIOLIB
- select GEODE_COMMON
- help
- This option enables system support for the Soekris Engineering net5501.
- config GEOS
- bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
- select GPIOLIB
- select GEODE_COMMON
- depends on DMI
- help
- This option enables system support for the Traverse Technologies GEOS.
- config TS5500
- bool "Technologic Systems TS-5500 platform support"
- depends on MELAN
- select CHECK_SIGNATURE
- select NEW_LEDS
- select LEDS_CLASS
- help
- This option enables system support for the Technologic Systems TS-5500.
- endif # X86_32
- config AMD_NB
- def_bool y
- depends on CPU_SUP_AMD && PCI
- endmenu
- menu "Binary Emulations"
- config IA32_EMULATION
- bool "IA32 Emulation"
- depends on X86_64
- select ARCH_WANT_OLD_COMPAT_IPC
- select BINFMT_ELF
- select COMPAT_OLD_SIGACTION
- help
- Include code to run legacy 32-bit programs under a
- 64-bit kernel. You should likely turn this on, unless you're
- 100% sure that you don't have any 32-bit programs left.
- config IA32_EMULATION_DEFAULT_DISABLED
- bool "IA32 emulation disabled by default"
- default n
- depends on IA32_EMULATION
- help
- Make IA32 emulation disabled by default. This prevents loading 32-bit
- processes and access to 32-bit syscalls. If unsure, leave it to its
- default value.
- config X86_X32_ABI
- bool "x32 ABI for 64-bit mode"
- depends on X86_64
- # llvm-objcopy does not convert x86_64 .note.gnu.property or
- # compressed debug sections to x86_x32 properly:
- # https://github.com/ClangBuiltLinux/linux/issues/514
- # https://github.com/ClangBuiltLinux/linux/issues/1141
- depends on $(success,$(OBJCOPY) --version | head -n1 | grep -qv llvm)
- help
- Include code to run binaries for the x32 native 32-bit ABI
- for 64-bit processors. An x32 process gets access to the
- full 64-bit register file and wide data path while leaving
- pointers at 32 bits for smaller memory footprint.
- config COMPAT_32
- def_bool y
- depends on IA32_EMULATION || X86_32
- select HAVE_UID16
- select OLD_SIGSUSPEND3
- config COMPAT
- def_bool y
- depends on IA32_EMULATION || X86_X32_ABI
- config COMPAT_FOR_U64_ALIGNMENT
- def_bool y
- depends on COMPAT
- endmenu
- config HAVE_ATOMIC_IOMAP
- def_bool y
- depends on X86_32
- source "arch/x86/kvm/Kconfig"
- source "arch/x86/Kconfig.assembler"
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