1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select HAVE_DEBUG_STACKOVERFLOW
18 select MODULES_USE_ELF_REL
20 select GENERIC_VDSO_32
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE
27 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select NEED_DMA_MAP_STATE
34 config FORCE_DYNAMIC_FTRACE
37 depends on FUNCTION_TRACER
40 We keep the static function tracing (!DYNAMIC_FTRACE) around
41 in order to test the non static function tracing in the
42 generic code, as other architectures still use it. But we
43 only need to keep it around for x86_64. No need to keep it
44 for x86_32. For x86_32, force DYNAMIC_FTRACE.
48 # ( Note that options that are marked 'if X86_64' could in principle be
49 # ported to 32-bit as well. )
54 # Note: keep this list sorted alphabetically
56 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
57 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
58 select ARCH_32BIT_OFF_T if X86_32
59 select ARCH_CLOCKSOURCE_INIT
60 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
61 select ARCH_HAS_DEBUG_VIRTUAL
62 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
63 select ARCH_HAS_DEVMEM_IS_ALLOWED
64 select ARCH_HAS_EARLY_DEBUG if KGDB
65 select ARCH_HAS_ELF_RANDOMIZE
66 select ARCH_HAS_FAST_MULTIPLIER
67 select ARCH_HAS_FILTER_PGPROT
68 select ARCH_HAS_FORTIFY_SOURCE
69 select ARCH_HAS_GCOV_PROFILE_ALL
70 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
71 select ARCH_HAS_MEM_ENCRYPT
72 select ARCH_HAS_MEMBARRIER_SYNC_CORE
73 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
74 select ARCH_HAS_PMEM_API if X86_64
75 select ARCH_HAS_PTE_DEVMAP if X86_64
76 select ARCH_HAS_PTE_SPECIAL
77 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
78 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
79 select ARCH_HAS_SET_MEMORY
80 select ARCH_HAS_SET_DIRECT_MAP
81 select ARCH_HAS_STRICT_KERNEL_RWX
82 select ARCH_HAS_STRICT_MODULE_RWX
83 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
84 select ARCH_HAS_SYSCALL_WRAPPER
85 select ARCH_HAS_UBSAN_SANITIZE_ALL
86 select ARCH_HAS_DEBUG_WX
87 select ARCH_HAVE_NMI_SAFE_CMPXCHG
88 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
89 select ARCH_MIGHT_HAVE_PC_PARPORT
90 select ARCH_MIGHT_HAVE_PC_SERIO
92 select ARCH_SUPPORTS_ACPI
93 select ARCH_SUPPORTS_ATOMIC_RMW
94 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
95 select ARCH_USE_BUILTIN_BSWAP
96 select ARCH_USE_QUEUED_RWLOCKS
97 select ARCH_USE_QUEUED_SPINLOCKS
98 select ARCH_USE_SYM_ANNOTATIONS
99 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
100 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
101 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
102 select ARCH_WANT_HUGE_PMD_SHARE
103 select ARCH_WANTS_THP_SWAP if X86_64
104 select BUILDTIME_TABLE_SORT
106 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
107 select CLOCKSOURCE_WATCHDOG
108 select DCACHE_WORD_ACCESS
109 select EDAC_ATOMIC_SCRUB
111 select GENERIC_CLOCKEVENTS
112 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
113 select GENERIC_CLOCKEVENTS_MIN_ADJUST
114 select GENERIC_CMOS_UPDATE
115 select GENERIC_CPU_AUTOPROBE
116 select GENERIC_CPU_VULNERABILITIES
117 select GENERIC_EARLY_IOREMAP
118 select GENERIC_FIND_FIRST_BIT
120 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
121 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
122 select GENERIC_IRQ_MIGRATION if SMP
123 select GENERIC_IRQ_PROBE
124 select GENERIC_IRQ_RESERVATION_MODE
125 select GENERIC_IRQ_SHOW
126 select GENERIC_PENDING_IRQ if SMP
127 select GENERIC_PTDUMP
128 select GENERIC_SMP_IDLE_THREAD
129 select GENERIC_STRNCPY_FROM_USER
130 select GENERIC_STRNLEN_USER
131 select GENERIC_TIME_VSYSCALL
132 select GENERIC_GETTIMEOFDAY
133 select GENERIC_VDSO_TIME_NS
134 select GUP_GET_PTE_LOW_HIGH if X86_PAE
135 select HARDIRQS_SW_RESEND
136 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
137 select HAVE_ACPI_APEI if ACPI
138 select HAVE_ACPI_APEI_NMI if ACPI
139 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
140 select HAVE_ARCH_AUDITSYSCALL
141 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
142 select HAVE_ARCH_JUMP_LABEL
143 select HAVE_ARCH_JUMP_LABEL_RELATIVE
144 select HAVE_ARCH_KASAN if X86_64
145 select HAVE_ARCH_KASAN_VMALLOC if X86_64
146 select HAVE_ARCH_KGDB
147 select HAVE_ARCH_MMAP_RND_BITS if MMU
148 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
149 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
150 select HAVE_ARCH_PREL32_RELOCATIONS
151 select HAVE_ARCH_SECCOMP_FILTER
152 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
153 select HAVE_ARCH_STACKLEAK
154 select HAVE_ARCH_TRACEHOOK
155 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
156 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
157 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
158 select HAVE_ARCH_VMAP_STACK if X86_64
159 select HAVE_ARCH_WITHIN_STACK_FRAMES
160 select HAVE_ASM_MODVERSIONS
161 select HAVE_CMPXCHG_DOUBLE
162 select HAVE_CMPXCHG_LOCAL
163 select HAVE_CONTEXT_TRACKING if X86_64
164 select HAVE_COPY_THREAD_TLS
165 select HAVE_C_RECORDMCOUNT
166 select HAVE_DEBUG_KMEMLEAK
167 select HAVE_DMA_CONTIGUOUS
168 select HAVE_DYNAMIC_FTRACE
169 select HAVE_DYNAMIC_FTRACE_WITH_REGS
170 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
172 select HAVE_EFFICIENT_UNALIGNED_ACCESS
174 select HAVE_EXIT_THREAD
176 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
177 select HAVE_FTRACE_MCOUNT_RECORD
178 select HAVE_FUNCTION_GRAPH_TRACER
179 select HAVE_FUNCTION_TRACER
180 select HAVE_GCC_PLUGINS
181 select HAVE_HW_BREAKPOINT
183 select HAVE_IOREMAP_PROT
184 select HAVE_IRQ_TIME_ACCOUNTING
185 select HAVE_KERNEL_BZIP2
186 select HAVE_KERNEL_GZIP
187 select HAVE_KERNEL_LZ4
188 select HAVE_KERNEL_LZMA
189 select HAVE_KERNEL_LZO
190 select HAVE_KERNEL_XZ
192 select HAVE_KPROBES_ON_FTRACE
193 select HAVE_FUNCTION_ERROR_INJECTION
194 select HAVE_KRETPROBES
196 select HAVE_LIVEPATCH if X86_64
197 select HAVE_MIXED_BREAKPOINTS_REGS
198 select HAVE_MOD_ARCH_SPECIFIC
202 select HAVE_OPTPROBES
203 select HAVE_PCSPKR_PLATFORM
204 select HAVE_PERF_EVENTS
205 select HAVE_PERF_EVENTS_NMI
206 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
208 select HAVE_PERF_REGS
209 select HAVE_PERF_USER_STACK_DUMP
210 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
211 select HAVE_REGS_AND_STACK_ACCESS_API
212 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
213 select HAVE_FUNCTION_ARG_ACCESS_API
214 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
215 select HAVE_STACK_VALIDATION if X86_64
217 select HAVE_SYSCALL_TRACEPOINTS
218 select HAVE_UNSTABLE_SCHED_CLOCK
219 select HAVE_USER_RETURN_NOTIFIER
220 select HAVE_GENERIC_VDSO
221 select HOTPLUG_SMT if SMP
222 select IRQ_FORCED_THREADING
223 select NEED_SG_DMA_LENGTH
224 select PCI_DOMAINS if PCI
225 select PCI_LOCKLESS_CONFIG if PCI
228 select RTC_MC146818_LIB
231 select SYSCTL_EXCEPTION_TRACE
232 select THREAD_INFO_IN_TASK
233 select USER_STACKTRACE_SUPPORT
235 select HAVE_ARCH_KCSAN if X86_64
236 select X86_FEATURE_NAMES if PROC_FS
237 select PROC_PID_ARCH_STATUS if PROC_FS
238 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
240 config INSTRUCTION_DECODER
242 depends on KPROBES || PERF_EVENTS || UPROBES
246 default "elf32-i386" if X86_32
247 default "elf64-x86-64" if X86_64
249 config LOCKDEP_SUPPORT
252 config STACKTRACE_SUPPORT
258 config ARCH_MMAP_RND_BITS_MIN
262 config ARCH_MMAP_RND_BITS_MAX
266 config ARCH_MMAP_RND_COMPAT_BITS_MIN
269 config ARCH_MMAP_RND_COMPAT_BITS_MAX
275 config GENERIC_ISA_DMA
277 depends on ISA_DMA_API
282 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
284 config GENERIC_BUG_RELATIVE_POINTERS
287 config ARCH_MAY_HAVE_PC_FDC
289 depends on ISA_DMA_API
291 config GENERIC_CALIBRATE_DELAY
294 config ARCH_HAS_CPU_RELAX
297 config ARCH_HAS_CACHE_LINE_SIZE
300 config ARCH_HAS_FILTER_PGPROT
303 config HAVE_SETUP_PER_CPU_AREA
306 config NEED_PER_CPU_EMBED_FIRST_CHUNK
309 config NEED_PER_CPU_PAGE_FIRST_CHUNK
312 config ARCH_HIBERNATION_POSSIBLE
315 config ARCH_SUSPEND_POSSIBLE
318 config ARCH_WANT_GENERAL_HUGETLB
327 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
330 config KASAN_SHADOW_OFFSET
333 default 0xdffffc0000000000
335 config HAVE_INTEL_TXT
337 depends on INTEL_IOMMU && ACPI
341 depends on X86_32 && SMP
345 depends on X86_64 && SMP
347 config X86_32_LAZY_GS
349 depends on X86_32 && !STACKPROTECTOR
351 config ARCH_SUPPORTS_UPROBES
354 config FIX_EARLYCON_MEM
357 config DYNAMIC_PHYSICAL_MASK
360 config PGTABLE_LEVELS
362 default 5 if X86_5LEVEL
367 config CC_HAS_SANE_STACKPROTECTOR
369 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
370 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
372 We have to make sure stack protector is unconditionally disabled if
373 the compiler produces broken code.
375 menu "Processor type and features"
378 bool "DMA memory allocation support" if EXPERT
381 DMA memory allocation support allows devices with less than 32-bit
382 addressing to allocate within the first 16MB of address space.
383 Disable if no such devices will be used.
388 bool "Symmetric multi-processing support"
390 This enables support for systems with more than one CPU. If you have
391 a system with only one CPU, say N. If you have a system with more
394 If you say N here, the kernel will run on uni- and multiprocessor
395 machines, but will use only one CPU of a multiprocessor machine. If
396 you say Y here, the kernel will run on many, but not all,
397 uniprocessor machines. On a uniprocessor machine, the kernel
398 will run faster if you say N here.
400 Note that if you say Y here and choose architecture "586" or
401 "Pentium" under "Processor family", the kernel will not work on 486
402 architectures. Similarly, multiprocessor kernels for the "PPro"
403 architecture may not work on all Pentium based boards.
405 People using multiprocessor machines who say Y here should also say
406 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
407 Management" code will be disabled if you say Y here.
409 See also <file:Documentation/x86/i386/IO-APIC.rst>,
410 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
411 <http://www.tldp.org/docs.html#howto>.
413 If you don't know what to do here, say N.
415 config X86_FEATURE_NAMES
416 bool "Processor feature human-readable names" if EMBEDDED
419 This option compiles in a table of x86 feature bits and corresponding
420 names. This is required to support /proc/cpuinfo and a few kernel
421 messages. You can disable this to save space, at the expense of
422 making those few kernel messages show numeric feature bits instead.
427 bool "Support x2apic"
428 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
430 This enables x2apic support on CPUs that have this feature.
432 This allows 32-bit apic IDs (so it can support very large systems),
433 and accesses the local apic via MSRs not via mmio.
435 If you don't know what to do here, say N.
438 bool "Enable MPS table" if ACPI || SFI
440 depends on X86_LOCAL_APIC
442 For old smp systems that do not have proper acpi support. Newer systems
443 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
447 depends on X86_GOLDFISH
450 bool "Avoid speculative indirect branches in kernel"
452 select STACK_VALIDATION if HAVE_STACK_VALIDATION
454 Compile kernel with the retpoline compiler options to guard against
455 kernel-to-user data leaks by avoiding speculative indirect
456 branches. Requires a compiler with -mindirect-branch=thunk-extern
457 support for full protection. The kernel may run slower.
459 config X86_CPU_RESCTRL
460 bool "x86 CPU resource control support"
461 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
463 select PROC_CPU_RESCTRL if PROC_FS
465 Enable x86 CPU resource control support.
467 Provide support for the allocation and monitoring of system resources
470 Intel calls this Intel Resource Director Technology
471 (Intel(R) RDT). More information about RDT can be found in the
472 Intel x86 Architecture Software Developer Manual.
474 AMD calls this AMD Platform Quality of Service (AMD QoS).
475 More information about AMD QoS can be found in the AMD64 Technology
476 Platform Quality of Service Extensions manual.
482 bool "Support for big SMP systems with more than 8 CPUs"
485 This option is needed for the systems that have more than 8 CPUs.
487 config X86_EXTENDED_PLATFORM
488 bool "Support for extended (non-PC) x86 platforms"
491 If you disable this option then the kernel will only support
492 standard PC platforms. (which covers the vast majority of
495 If you enable this option then you'll be able to select support
496 for the following (non-PC) 32 bit x86 platforms:
497 Goldfish (Android emulator)
500 SGI 320/540 (Visual Workstation)
501 STA2X11-based (e.g. Northville)
502 Moorestown MID devices
504 If you have one of these systems, or if you want to build a
505 generic distribution kernel, say Y here - otherwise say N.
509 config X86_EXTENDED_PLATFORM
510 bool "Support for extended (non-PC) x86 platforms"
513 If you disable this option then the kernel will only support
514 standard PC platforms. (which covers the vast majority of
517 If you enable this option then you'll be able to select support
518 for the following (non-PC) 64 bit x86 platforms:
523 If you have one of these systems, or if you want to build a
524 generic distribution kernel, say Y here - otherwise say N.
526 # This is an alphabetically sorted list of 64 bit extended platforms
527 # Please maintain the alphabetic order if and when there are additions
529 bool "Numascale NumaChip"
531 depends on X86_EXTENDED_PLATFORM
534 depends on X86_X2APIC
535 depends on PCI_MMCONFIG
537 Adds support for Numascale NumaChip large-SMP systems. Needed to
538 enable more than ~168 cores.
539 If you don't have one of these, you should say N here.
543 select HYPERVISOR_GUEST
545 depends on X86_64 && PCI
546 depends on X86_EXTENDED_PLATFORM
549 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
550 supposed to run on these EM64T-based machines. Only choose this option
551 if you have one of these machines.
554 bool "SGI Ultraviolet"
556 depends on X86_EXTENDED_PLATFORM
559 depends on X86_X2APIC
562 This option is needed in order to support SGI Ultraviolet systems.
563 If you don't have one of these, you should say N here.
565 # Following is an alphabetically sorted list of 32 bit extended platforms
566 # Please maintain the alphabetic order if and when there are additions
569 bool "Goldfish (Virtual Platform)"
570 depends on X86_EXTENDED_PLATFORM
572 Enable support for the Goldfish virtual platform used primarily
573 for Android development. Unless you are building for the Android
574 Goldfish emulator say N here.
577 bool "CE4100 TV platform"
579 depends on PCI_GODIRECT
580 depends on X86_IO_APIC
582 depends on X86_EXTENDED_PLATFORM
583 select X86_REBOOTFIXUPS
585 select OF_EARLY_FLATTREE
587 Select for the Intel CE media processor (CE4100) SOC.
588 This option compiles in support for the CE4100 SOC for settop
589 boxes and media devices.
592 bool "Intel MID platform support"
593 depends on X86_EXTENDED_PLATFORM
594 depends on X86_PLATFORM_DEVICES
596 depends on X86_64 || (PCI_GOANY && X86_32)
597 depends on X86_IO_APIC
603 select MFD_INTEL_MSIC
605 Select to build a kernel capable of supporting Intel MID (Mobile
606 Internet Device) platform systems which do not have the PCI legacy
607 interfaces. If you are building for a PC class system say N here.
609 Intel MID platforms are based on an Intel processor and chipset which
610 consume less power than most of the x86 derivatives.
612 config X86_INTEL_QUARK
613 bool "Intel Quark platform support"
615 depends on X86_EXTENDED_PLATFORM
616 depends on X86_PLATFORM_DEVICES
620 depends on X86_IO_APIC
625 Select to include support for Quark X1000 SoC.
626 Say Y here if you have a Quark based system such as the Arduino
627 compatible Intel Galileo.
629 config X86_INTEL_LPSS
630 bool "Intel Low Power Subsystem Support"
631 depends on X86 && ACPI && PCI
636 Select to build support for Intel Low Power Subsystem such as
637 found on Intel Lynxpoint PCH. Selecting this option enables
638 things like clock tree (common clock framework) and pincontrol
639 which are needed by the LPSS peripheral drivers.
641 config X86_AMD_PLATFORM_DEVICE
642 bool "AMD ACPI2Platform devices support"
647 Select to interpret AMD specific ACPI device to platform device
648 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
649 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
650 implemented under PINCTRL subsystem.
653 tristate "Intel SoC IOSF Sideband support for SoC platforms"
656 This option enables sideband register access support for Intel SoC
657 platforms. On these platforms the IOSF sideband is used in lieu of
658 MSR's for some register accesses, mostly but not limited to thermal
659 and power. Drivers may query the availability of this device to
660 determine if they need the sideband in order to work on these
661 platforms. The sideband is available on the following SoC products.
662 This list is not meant to be exclusive.
667 You should say Y if you are running a kernel on one of these SoC's.
669 config IOSF_MBI_DEBUG
670 bool "Enable IOSF sideband access through debugfs"
671 depends on IOSF_MBI && DEBUG_FS
673 Select this option to expose the IOSF sideband access registers (MCR,
674 MDR, MCRX) through debugfs to write and read register information from
675 different units on the SoC. This is most useful for obtaining device
676 state information for debug and analysis. As this is a general access
677 mechanism, users of this option would have specific knowledge of the
678 device they want to access.
680 If you don't require the option or are in doubt, say N.
683 bool "RDC R-321x SoC"
685 depends on X86_EXTENDED_PLATFORM
687 select X86_REBOOTFIXUPS
689 This option is needed for RDC R-321x system-on-chip, also known
691 If you don't have one of these chips, you should say N here.
693 config X86_32_NON_STANDARD
694 bool "Support non-standard 32-bit SMP architectures"
695 depends on X86_32 && SMP
696 depends on X86_EXTENDED_PLATFORM
698 This option compiles in the bigsmp and STA2X11 default
699 subarchitectures. It is intended for a generic binary
700 kernel. If you select them all, kernel will probe it one by
701 one and will fallback to default.
703 # Alphabetically sorted list of Non standard 32 bit platforms
705 config X86_SUPPORTS_MEMORY_FAILURE
707 # MCE code calls memory_failure():
709 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
710 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
711 depends on X86_64 || !SPARSEMEM
712 select ARCH_SUPPORTS_MEMORY_FAILURE
715 bool "STA2X11 Companion Chip Support"
716 depends on X86_32_NON_STANDARD && PCI
721 This adds support for boards based on the STA2X11 IO-Hub,
722 a.k.a. "ConneXt". The chip is used in place of the standard
723 PC chipset, so all "standard" peripherals are missing. If this
724 option is selected the kernel will still be able to boot on
725 standard PC machines.
728 tristate "Eurobraille/Iris poweroff module"
731 The Iris machines from EuroBraille do not have APM or ACPI support
732 to shut themselves down properly. A special I/O sequence is
733 needed to do so, which is what this module does at
736 This is only for Iris machines from EuroBraille.
740 config SCHED_OMIT_FRAME_POINTER
742 prompt "Single-depth WCHAN output"
745 Calculate simpler /proc/<PID>/wchan values. If this option
746 is disabled then wchan values will recurse back to the
747 caller function. This provides more accurate wchan values,
748 at the expense of slightly more scheduling overhead.
750 If in doubt, say "Y".
752 menuconfig HYPERVISOR_GUEST
753 bool "Linux guest support"
755 Say Y here to enable options for running Linux under various hyper-
756 visors. This option enables basic hypervisor detection and platform
759 If you say N, all options in this submenu will be skipped and
760 disabled, and Linux guest support won't be built in.
765 bool "Enable paravirtualization code"
767 This changes the kernel so it can modify itself when it is run
768 under a hypervisor, potentially improving performance significantly
769 over full virtualization. However, when run without a hypervisor
770 the kernel is theoretically slower and slightly larger.
775 config PARAVIRT_DEBUG
776 bool "paravirt-ops debugging"
777 depends on PARAVIRT && DEBUG_KERNEL
779 Enable to debug paravirt_ops internals. Specifically, BUG if
780 a paravirt_op is missing when it is called.
782 config PARAVIRT_SPINLOCKS
783 bool "Paravirtualization layer for spinlocks"
784 depends on PARAVIRT && SMP
786 Paravirtualized spinlocks allow a pvops backend to replace the
787 spinlock implementation with something virtualization-friendly
788 (for example, block the virtual CPU rather than spinning).
790 It has a minimal impact on native kernels and gives a nice performance
791 benefit on paravirtualized KVM / Xen kernels.
793 If you are unsure how to answer this question, answer Y.
795 config X86_HV_CALLBACK_VECTOR
798 source "arch/x86/xen/Kconfig"
801 bool "KVM Guest support (including kvmclock)"
803 select PARAVIRT_CLOCK
804 select ARCH_CPUIDLE_HALTPOLL
807 This option enables various optimizations for running under the KVM
808 hypervisor. It includes a paravirtualized clock, so that instead
809 of relying on a PIT (or probably other) emulation by the
810 underlying device model, the host provides the guest with
811 timing infrastructure such as time of day, and system time
813 config ARCH_CPUIDLE_HALTPOLL
815 prompt "Disable host haltpoll when loading haltpoll driver"
817 If virtualized under KVM, disable host haltpoll.
820 bool "Support for running PVH guests"
822 This option enables the PVH entry point for guest virtual machines
823 as specified in the x86/HVM direct boot ABI.
825 config PARAVIRT_TIME_ACCOUNTING
826 bool "Paravirtual steal time accounting"
829 Select this option to enable fine granularity task steal time
830 accounting. Time spent executing other tasks in parallel with
831 the current vCPU is discounted from the vCPU power. To account for
832 that, there can be a small performance impact.
834 If in doubt, say N here.
836 config PARAVIRT_CLOCK
839 config JAILHOUSE_GUEST
840 bool "Jailhouse non-root cell support"
841 depends on X86_64 && PCI
844 This option allows to run Linux as guest in a Jailhouse non-root
845 cell. You can leave this option disabled if you only want to start
846 Jailhouse and run Linux afterwards in the root cell.
849 bool "ACRN Guest support"
851 select X86_HV_CALLBACK_VECTOR
853 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
854 a flexible, lightweight reference open-source hypervisor, built with
855 real-time and safety-criticality in mind. It is built for embedded
856 IOT with small footprint and real-time features. More details can be
857 found in https://projectacrn.org/.
859 endif #HYPERVISOR_GUEST
861 source "arch/x86/Kconfig.cpu"
865 prompt "HPET Timer Support" if X86_32
867 Use the IA-PC HPET (High Precision Event Timer) to manage
868 time in preference to the PIT and RTC, if a HPET is
870 HPET is the next generation timer replacing legacy 8254s.
871 The HPET provides a stable time base on SMP
872 systems, unlike the TSC, but it is more expensive to access,
873 as it is off-chip. The interface used is documented
874 in the HPET spec, revision 1.
876 You can safely choose Y here. However, HPET will only be
877 activated if the platform and the BIOS support this feature.
878 Otherwise the 8254 will be used for timing services.
880 Choose N to continue using the legacy 8254 timer.
882 config HPET_EMULATE_RTC
884 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
887 def_bool y if X86_INTEL_MID
888 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
890 depends on X86_INTEL_MID && SFI
892 APB timer is the replacement for 8254, HPET on X86 MID platforms.
893 The APBT provides a stable time base on SMP
894 systems, unlike the TSC, but it is more expensive to access,
895 as it is off-chip. APB timers are always running regardless of CPU
896 C states, they are used as per CPU clockevent device when possible.
898 # Mark as expert because too many people got it wrong.
899 # The code disables itself when not needed.
902 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
903 bool "Enable DMI scanning" if EXPERT
905 Enabled scanning of DMI to identify machine quirks. Say Y
906 here unless you have verified that your setup is not
907 affected by entries in the DMI blacklist. Required by PNP
911 bool "Old AMD GART IOMMU support"
914 depends on X86_64 && PCI && AMD_NB
916 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
917 GART based hardware IOMMUs.
919 The GART supports full DMA access for devices with 32-bit access
920 limitations, on systems with more than 3 GB. This is usually needed
921 for USB, sound, many IDE/SATA chipsets and some other devices.
923 Newer systems typically have a modern AMD IOMMU, supported via
924 the CONFIG_AMD_IOMMU=y config option.
926 In normal configurations this driver is only active when needed:
927 there's more than 3 GB of memory and the system contains a
928 32-bit limited device.
933 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
934 depends on X86_64 && SMP && DEBUG_KERNEL
935 select CPUMASK_OFFSTACK
937 Enable maximum number of CPUS and NUMA Nodes for this architecture.
941 # The maximum number of CPUs supported:
943 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
944 # and which can be configured interactively in the
945 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
947 # The ranges are different on 32-bit and 64-bit kernels, depending on
948 # hardware capabilities and scalability features of the kernel.
950 # ( If MAXSMP is enabled we just use the highest possible value and disable
951 # interactive configuration. )
954 config NR_CPUS_RANGE_BEGIN
956 default NR_CPUS_RANGE_END if MAXSMP
960 config NR_CPUS_RANGE_END
963 default 64 if SMP && X86_BIGSMP
964 default 8 if SMP && !X86_BIGSMP
967 config NR_CPUS_RANGE_END
970 default 8192 if SMP && CPUMASK_OFFSTACK
971 default 512 if SMP && !CPUMASK_OFFSTACK
974 config NR_CPUS_DEFAULT
977 default 32 if X86_BIGSMP
981 config NR_CPUS_DEFAULT
984 default 8192 if MAXSMP
989 int "Maximum number of CPUs" if SMP && !MAXSMP
990 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
991 default NR_CPUS_DEFAULT
993 This allows you to specify the maximum number of CPUs which this
994 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
995 supported value is 8192, otherwise the maximum value is 512. The
996 minimum value which makes sense is 2.
998 This is purely to save memory: each supported CPU adds about 8KB
1006 prompt "Multi-core scheduler support"
1009 Multi-core scheduler support improves the CPU scheduler's decision
1010 making when dealing with multi-core CPU chips at a cost of slightly
1011 increased overhead in some places. If unsure say N here.
1013 config SCHED_MC_PRIO
1014 bool "CPU core priorities scheduler support"
1015 depends on SCHED_MC && CPU_SUP_INTEL
1016 select X86_INTEL_PSTATE
1020 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1021 core ordering determined at manufacturing time, which allows
1022 certain cores to reach higher turbo frequencies (when running
1023 single threaded workloads) than others.
1025 Enabling this kernel feature teaches the scheduler about
1026 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1027 scheduler's CPU selection logic accordingly, so that higher
1028 overall system performance can be achieved.
1030 This feature will have no effect on CPUs without this feature.
1032 If unsure say Y here.
1036 depends on !SMP && X86_LOCAL_APIC
1039 bool "Local APIC support on uniprocessors" if !PCI_MSI
1041 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1043 A local APIC (Advanced Programmable Interrupt Controller) is an
1044 integrated interrupt controller in the CPU. If you have a single-CPU
1045 system which has a processor with a local APIC, you can say Y here to
1046 enable and use it. If you say Y here even though your machine doesn't
1047 have a local APIC, then the kernel will still run with no slowdown at
1048 all. The local APIC supports CPU-generated self-interrupts (timer,
1049 performance counters), and the NMI watchdog which detects hard
1052 config X86_UP_IOAPIC
1053 bool "IO-APIC support on uniprocessors"
1054 depends on X86_UP_APIC
1056 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1057 SMP-capable replacement for PC-style interrupt controllers. Most
1058 SMP systems and many recent uniprocessor systems have one.
1060 If you have a single-CPU system with an IO-APIC, you can say Y here
1061 to use it. If you say Y here even though your machine doesn't have
1062 an IO-APIC, then the kernel will still run with no slowdown at all.
1064 config X86_LOCAL_APIC
1066 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1067 select IRQ_DOMAIN_HIERARCHY
1068 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1072 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1074 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1075 bool "Reroute for broken boot IRQs"
1076 depends on X86_IO_APIC
1078 This option enables a workaround that fixes a source of
1079 spurious interrupts. This is recommended when threaded
1080 interrupt handling is used on systems where the generation of
1081 superfluous "boot interrupts" cannot be disabled.
1083 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1084 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1085 kernel does during interrupt handling). On chipsets where this
1086 boot IRQ generation cannot be disabled, this workaround keeps
1087 the original IRQ line masked so that only the equivalent "boot
1088 IRQ" is delivered to the CPUs. The workaround also tells the
1089 kernel to set up the IRQ handler on the boot IRQ line. In this
1090 way only one interrupt is delivered to the kernel. Otherwise
1091 the spurious second interrupt may cause the kernel to bring
1092 down (vital) interrupt lines.
1094 Only affects "broken" chipsets. Interrupt sharing may be
1095 increased on these systems.
1098 bool "Machine Check / overheating reporting"
1099 select GENERIC_ALLOCATOR
1102 Machine Check support allows the processor to notify the
1103 kernel if it detects a problem (e.g. overheating, data corruption).
1104 The action the kernel takes depends on the severity of the problem,
1105 ranging from warning messages to halting the machine.
1107 config X86_MCELOG_LEGACY
1108 bool "Support for deprecated /dev/mcelog character device"
1111 Enable support for /dev/mcelog which is needed by the old mcelog
1112 userspace logging daemon. Consider switching to the new generation
1115 config X86_MCE_INTEL
1117 prompt "Intel MCE features"
1118 depends on X86_MCE && X86_LOCAL_APIC
1120 Additional support for intel specific MCE features such as
1121 the thermal monitor.
1125 prompt "AMD MCE features"
1126 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1128 Additional support for AMD specific MCE features such as
1129 the DRAM Error Threshold.
1131 config X86_ANCIENT_MCE
1132 bool "Support for old Pentium 5 / WinChip machine checks"
1133 depends on X86_32 && X86_MCE
1135 Include support for machine check handling on old Pentium 5 or WinChip
1136 systems. These typically need to be enabled explicitly on the command
1139 config X86_MCE_THRESHOLD
1140 depends on X86_MCE_AMD || X86_MCE_INTEL
1143 config X86_MCE_INJECT
1144 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1145 tristate "Machine check injector support"
1147 Provide support for injecting machine checks for testing purposes.
1148 If you don't know what a machine check is and you don't do kernel
1149 QA it is safe to say n.
1151 config X86_THERMAL_VECTOR
1153 depends on X86_MCE_INTEL
1155 source "arch/x86/events/Kconfig"
1157 config X86_LEGACY_VM86
1158 bool "Legacy VM86 support"
1161 This option allows user programs to put the CPU into V8086
1162 mode, which is an 80286-era approximation of 16-bit real mode.
1164 Some very old versions of X and/or vbetool require this option
1165 for user mode setting. Similarly, DOSEMU will use it if
1166 available to accelerate real mode DOS programs. However, any
1167 recent version of DOSEMU, X, or vbetool should be fully
1168 functional even without kernel VM86 support, as they will all
1169 fall back to software emulation. Nevertheless, if you are using
1170 a 16-bit DOS program where 16-bit performance matters, vm86
1171 mode might be faster than emulation and you might want to
1174 Note that any app that works on a 64-bit kernel is unlikely to
1175 need this option, as 64-bit kernels don't, and can't, support
1176 V8086 mode. This option is also unrelated to 16-bit protected
1177 mode and is not needed to run most 16-bit programs under Wine.
1179 Enabling this option increases the complexity of the kernel
1180 and slows down exception handling a tiny bit.
1182 If unsure, say N here.
1186 default X86_LEGACY_VM86
1189 bool "Enable support for 16-bit segments" if EXPERT
1191 depends on MODIFY_LDT_SYSCALL
1193 This option is required by programs like Wine to run 16-bit
1194 protected mode legacy code on x86 processors. Disabling
1195 this option saves about 300 bytes on i386, or around 6K text
1196 plus 16K runtime memory on x86-64,
1200 depends on X86_16BIT && X86_32
1204 depends on X86_16BIT && X86_64
1206 config X86_VSYSCALL_EMULATION
1207 bool "Enable vsyscall emulation" if EXPERT
1211 This enables emulation of the legacy vsyscall page. Disabling
1212 it is roughly equivalent to booting with vsyscall=none, except
1213 that it will also disable the helpful warning if a program
1214 tries to use a vsyscall. With this option set to N, offending
1215 programs will just segfault, citing addresses of the form
1218 This option is required by many programs built before 2013, and
1219 care should be used even with newer programs if set to N.
1221 Disabling this option saves about 7K of kernel size and
1222 possibly 4K of additional runtime pagetable memory.
1224 config X86_IOPL_IOPERM
1225 bool "IOPERM and IOPL Emulation"
1228 This enables the ioperm() and iopl() syscalls which are necessary
1229 for legacy applications.
1231 Legacy IOPL support is an overbroad mechanism which allows user
1232 space aside of accessing all 65536 I/O ports also to disable
1233 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1234 capabilities and permission from potentially active security
1237 The emulation restricts the functionality of the syscall to
1238 only allowing the full range I/O port access, but prevents the
1239 ability to disable interrupts from user space which would be
1240 granted if the hardware IOPL mechanism would be used.
1243 tristate "Toshiba Laptop support"
1246 This adds a driver to safely access the System Management Mode of
1247 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1248 not work on models with a Phoenix BIOS. The System Management Mode
1249 is used to set the BIOS and power saving options on Toshiba portables.
1251 For information on utilities to make use of this driver see the
1252 Toshiba Linux utilities web site at:
1253 <http://www.buzzard.org.uk/toshiba/>.
1255 Say Y if you intend to run this kernel on a Toshiba portable.
1259 tristate "Dell i8k legacy laptop support"
1261 select SENSORS_DELL_SMM
1263 This option enables legacy /proc/i8k userspace interface in hwmon
1264 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1265 temperature and allows controlling fan speeds of Dell laptops via
1266 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1267 it reports also power and hotkey status. For fan speed control is
1268 needed userspace package i8kutils.
1270 Say Y if you intend to run this kernel on old Dell laptops or want to
1271 use userspace package i8kutils.
1274 config X86_REBOOTFIXUPS
1275 bool "Enable X86 board specific fixups for reboot"
1278 This enables chipset and/or board specific fixups to be done
1279 in order to get reboot to work correctly. This is only needed on
1280 some combinations of hardware and BIOS. The symptom, for which
1281 this config is intended, is when reboot ends with a stalled/hung
1284 Currently, the only fixup is for the Geode machines using
1285 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1287 Say Y if you want to enable the fixup. Currently, it's safe to
1288 enable this option even if you don't need it.
1292 bool "CPU microcode loading support"
1294 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1297 If you say Y here, you will be able to update the microcode on
1298 Intel and AMD processors. The Intel support is for the IA32 family,
1299 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1300 AMD support is for families 0x10 and later. You will obviously need
1301 the actual microcode binary data itself which is not shipped with
1304 The preferred method to load microcode from a detached initrd is described
1305 in Documentation/x86/microcode.rst. For that you need to enable
1306 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1307 initrd for microcode blobs.
1309 In addition, you can build the microcode into the kernel. For that you
1310 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1313 config MICROCODE_INTEL
1314 bool "Intel microcode loading support"
1315 depends on MICROCODE
1319 This options enables microcode patch loading support for Intel
1322 For the current Intel microcode data package go to
1323 <https://downloadcenter.intel.com> and search for
1324 'Linux Processor Microcode Data File'.
1326 config MICROCODE_AMD
1327 bool "AMD microcode loading support"
1328 depends on MICROCODE
1331 If you select this option, microcode patch loading support for AMD
1332 processors will be enabled.
1334 config MICROCODE_OLD_INTERFACE
1335 bool "Ancient loading interface (DEPRECATED)"
1337 depends on MICROCODE
1339 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1340 which was used by userspace tools like iucode_tool and microcode.ctl.
1341 It is inadequate because it runs too late to be able to properly
1342 load microcode on a machine and it needs special tools. Instead, you
1343 should've switched to the early loading method with the initrd or
1344 builtin microcode by now: Documentation/x86/microcode.rst
1347 tristate "/dev/cpu/*/msr - Model-specific register support"
1349 This device gives privileged processes access to the x86
1350 Model-Specific Registers (MSRs). It is a character device with
1351 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1352 MSR accesses are directed to a specific CPU on multi-processor
1356 tristate "/dev/cpu/*/cpuid - CPU information support"
1358 This device gives processes access to the x86 CPUID instruction to
1359 be executed on a specific processor. It is a character device
1360 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1364 prompt "High Memory Support"
1371 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1372 However, the address space of 32-bit x86 processors is only 4
1373 Gigabytes large. That means that, if you have a large amount of
1374 physical memory, not all of it can be "permanently mapped" by the
1375 kernel. The physical memory that's not permanently mapped is called
1378 If you are compiling a kernel which will never run on a machine with
1379 more than 1 Gigabyte total physical RAM, answer "off" here (default
1380 choice and suitable for most users). This will result in a "3GB/1GB"
1381 split: 3GB are mapped so that each process sees a 3GB virtual memory
1382 space and the remaining part of the 4GB virtual memory space is used
1383 by the kernel to permanently map as much physical memory as
1386 If the machine has between 1 and 4 Gigabytes physical RAM, then
1389 If more than 4 Gigabytes is used then answer "64GB" here. This
1390 selection turns Intel PAE (Physical Address Extension) mode on.
1391 PAE implements 3-level paging on IA32 processors. PAE is fully
1392 supported by Linux, PAE mode is implemented on all recent Intel
1393 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1394 then the kernel will not boot on CPUs that don't support PAE!
1396 The actual amount of total physical memory will either be
1397 auto detected or can be forced by using a kernel command line option
1398 such as "mem=256M". (Try "man bootparam" or see the documentation of
1399 your boot loader (lilo or loadlin) about how to pass options to the
1400 kernel at boot time.)
1402 If unsure, say "off".
1407 Select this if you have a 32-bit processor and between 1 and 4
1408 gigabytes of physical RAM.
1412 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1415 Select this if you have a 32-bit processor and more than 4
1416 gigabytes of physical RAM.
1421 prompt "Memory split" if EXPERT
1425 Select the desired split between kernel and user memory.
1427 If the address range available to the kernel is less than the
1428 physical memory installed, the remaining memory will be available
1429 as "high memory". Accessing high memory is a little more costly
1430 than low memory, as it needs to be mapped into the kernel first.
1431 Note that increasing the kernel address space limits the range
1432 available to user programs, making the address space there
1433 tighter. Selecting anything other than the default 3G/1G split
1434 will also likely make your kernel incompatible with binary-only
1437 If you are not absolutely sure what you are doing, leave this
1441 bool "3G/1G user/kernel split"
1442 config VMSPLIT_3G_OPT
1444 bool "3G/1G user/kernel split (for full 1G low memory)"
1446 bool "2G/2G user/kernel split"
1447 config VMSPLIT_2G_OPT
1449 bool "2G/2G user/kernel split (for full 2G low memory)"
1451 bool "1G/3G user/kernel split"
1456 default 0xB0000000 if VMSPLIT_3G_OPT
1457 default 0x80000000 if VMSPLIT_2G
1458 default 0x78000000 if VMSPLIT_2G_OPT
1459 default 0x40000000 if VMSPLIT_1G
1465 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1468 bool "PAE (Physical Address Extension) Support"
1469 depends on X86_32 && !HIGHMEM4G
1470 select PHYS_ADDR_T_64BIT
1473 PAE is required for NX support, and furthermore enables
1474 larger swapspace support for non-overcommit purposes. It
1475 has the cost of more pagetable lookup overhead, and also
1476 consumes more pagetable space per process.
1479 bool "Enable 5-level page tables support"
1481 select DYNAMIC_MEMORY_LAYOUT
1482 select SPARSEMEM_VMEMMAP
1485 5-level paging enables access to larger address space:
1486 upto 128 PiB of virtual address space and 4 PiB of
1487 physical address space.
1489 It will be supported by future Intel CPUs.
1491 A kernel with the option enabled can be booted on machines that
1492 support 4- or 5-level paging.
1494 See Documentation/x86/x86_64/5level-paging.rst for more
1499 config X86_DIRECT_GBPAGES
1503 Certain kernel features effectively disable kernel
1504 linear 1 GB mappings (even if the CPU otherwise
1505 supports them), so don't confuse the user by printing
1506 that we have them enabled.
1508 config X86_CPA_STATISTICS
1509 bool "Enable statistic for Change Page Attribute"
1512 Expose statistics about the Change Page Attribute mechanism, which
1513 helps to determine the effectiveness of preserving large and huge
1514 page mappings when mapping protections are changed.
1516 config AMD_MEM_ENCRYPT
1517 bool "AMD Secure Memory Encryption (SME) support"
1518 depends on X86_64 && CPU_SUP_AMD
1519 select DMA_COHERENT_POOL
1520 select DYNAMIC_PHYSICAL_MASK
1521 select ARCH_USE_MEMREMAP_PROT
1522 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1524 Say yes to enable support for the encryption of system memory.
1525 This requires an AMD processor that supports Secure Memory
1528 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1529 bool "Activate AMD Secure Memory Encryption (SME) by default"
1531 depends on AMD_MEM_ENCRYPT
1533 Say yes to have system memory encrypted by default if running on
1534 an AMD processor that supports Secure Memory Encryption (SME).
1536 If set to Y, then the encryption of system memory can be
1537 deactivated with the mem_encrypt=off command line option.
1539 If set to N, then the encryption of system memory can be
1540 activated with the mem_encrypt=on command line option.
1542 # Common NUMA Features
1544 bool "NUMA Memory Allocation and Scheduler Support"
1546 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1547 default y if X86_BIGSMP
1549 Enable NUMA (Non-Uniform Memory Access) support.
1551 The kernel will try to allocate memory used by a CPU on the
1552 local memory controller of the CPU and add some more
1553 NUMA awareness to the kernel.
1555 For 64-bit this is recommended if the system is Intel Core i7
1556 (or later), AMD Opteron, or EM64T NUMA.
1558 For 32-bit this is only needed if you boot a 32-bit
1559 kernel on a 64-bit NUMA platform.
1561 Otherwise, you should say N.
1565 prompt "Old style AMD Opteron NUMA detection"
1566 depends on X86_64 && NUMA && PCI
1568 Enable AMD NUMA node topology detection. You should say Y here if
1569 you have a multi processor AMD system. This uses an old method to
1570 read the NUMA configuration directly from the builtin Northbridge
1571 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1572 which also takes priority if both are compiled in.
1574 config X86_64_ACPI_NUMA
1576 prompt "ACPI NUMA detection"
1577 depends on X86_64 && NUMA && ACPI && PCI
1580 Enable ACPI SRAT based node topology detection.
1583 bool "NUMA emulation"
1586 Enable NUMA emulation. A flat machine will be split
1587 into virtual nodes when booted with "numa=fake=N", where N is the
1588 number of nodes. This is only useful for debugging.
1591 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1593 default "10" if MAXSMP
1594 default "6" if X86_64
1596 depends on NEED_MULTIPLE_NODES
1598 Specify the maximum number of NUMA Nodes available on the target
1599 system. Increases memory reserved to accommodate various tables.
1601 config ARCH_FLATMEM_ENABLE
1603 depends on X86_32 && !NUMA
1605 config ARCH_SPARSEMEM_ENABLE
1607 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1608 select SPARSEMEM_STATIC if X86_32
1609 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1611 config ARCH_SPARSEMEM_DEFAULT
1612 def_bool X86_64 || (NUMA && X86_32)
1614 config ARCH_SELECT_MEMORY_MODEL
1616 depends on ARCH_SPARSEMEM_ENABLE
1618 config ARCH_MEMORY_PROBE
1619 bool "Enable sysfs memory/probe interface"
1620 depends on X86_64 && MEMORY_HOTPLUG
1622 This option enables a sysfs memory/probe interface for testing.
1623 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1624 If you are unsure how to answer this question, answer N.
1626 config ARCH_PROC_KCORE_TEXT
1628 depends on X86_64 && PROC_KCORE
1630 config ILLEGAL_POINTER_VALUE
1633 default 0xdead000000000000 if X86_64
1635 config X86_PMEM_LEGACY_DEVICE
1638 config X86_PMEM_LEGACY
1639 tristate "Support non-standard NVDIMMs and ADR protected memory"
1640 depends on PHYS_ADDR_T_64BIT
1642 select X86_PMEM_LEGACY_DEVICE
1643 select NUMA_KEEP_MEMINFO if NUMA
1646 Treat memory marked using the non-standard e820 type of 12 as used
1647 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1648 The kernel will offer these regions to the 'pmem' driver so
1649 they can be used for persistent storage.
1654 bool "Allocate 3rd-level pagetables from highmem"
1657 The VM uses one page table entry for each page of physical memory.
1658 For systems with a lot of RAM, this can be wasteful of precious
1659 low memory. Setting this option will put user-space page table
1660 entries in high memory.
1662 config X86_CHECK_BIOS_CORRUPTION
1663 bool "Check for low memory corruption"
1665 Periodically check for memory corruption in low memory, which
1666 is suspected to be caused by BIOS. Even when enabled in the
1667 configuration, it is disabled at runtime. Enable it by
1668 setting "memory_corruption_check=1" on the kernel command
1669 line. By default it scans the low 64k of memory every 60
1670 seconds; see the memory_corruption_check_size and
1671 memory_corruption_check_period parameters in
1672 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1674 When enabled with the default parameters, this option has
1675 almost no overhead, as it reserves a relatively small amount
1676 of memory and scans it infrequently. It both detects corruption
1677 and prevents it from affecting the running system.
1679 It is, however, intended as a diagnostic tool; if repeatable
1680 BIOS-originated corruption always affects the same memory,
1681 you can use memmap= to prevent the kernel from using that
1684 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1685 bool "Set the default setting of memory_corruption_check"
1686 depends on X86_CHECK_BIOS_CORRUPTION
1689 Set whether the default state of memory_corruption_check is
1692 config X86_RESERVE_LOW
1693 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1697 Specify the amount of low memory to reserve for the BIOS.
1699 The first page contains BIOS data structures that the kernel
1700 must not use, so that page must always be reserved.
1702 By default we reserve the first 64K of physical RAM, as a
1703 number of BIOSes are known to corrupt that memory range
1704 during events such as suspend/resume or monitor cable
1705 insertion, so it must not be used by the kernel.
1707 You can set this to 4 if you are absolutely sure that you
1708 trust the BIOS to get all its memory reservations and usages
1709 right. If you know your BIOS have problems beyond the
1710 default 64K area, you can set this to 640 to avoid using the
1711 entire low memory range.
1713 If you have doubts about the BIOS (e.g. suspend/resume does
1714 not work or there's kernel crashes after certain hardware
1715 hotplug events) then you might want to enable
1716 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1717 typical corruption patterns.
1719 Leave this to the default value of 64 if you are unsure.
1721 config MATH_EMULATION
1723 depends on MODIFY_LDT_SYSCALL
1724 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1726 Linux can emulate a math coprocessor (used for floating point
1727 operations) if you don't have one. 486DX and Pentium processors have
1728 a math coprocessor built in, 486SX and 386 do not, unless you added
1729 a 487DX or 387, respectively. (The messages during boot time can
1730 give you some hints here ["man dmesg"].) Everyone needs either a
1731 coprocessor or this emulation.
1733 If you don't have a math coprocessor, you need to say Y here; if you
1734 say Y here even though you have a coprocessor, the coprocessor will
1735 be used nevertheless. (This behavior can be changed with the kernel
1736 command line option "no387", which comes handy if your coprocessor
1737 is broken. Try "man bootparam" or see the documentation of your boot
1738 loader (lilo or loadlin) about how to pass options to the kernel at
1739 boot time.) This means that it is a good idea to say Y here if you
1740 intend to use this kernel on different machines.
1742 More information about the internals of the Linux math coprocessor
1743 emulation can be found in <file:arch/x86/math-emu/README>.
1745 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1746 kernel, it won't hurt.
1750 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1752 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1753 the Memory Type Range Registers (MTRRs) may be used to control
1754 processor access to memory ranges. This is most useful if you have
1755 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1756 allows bus write transfers to be combined into a larger transfer
1757 before bursting over the PCI/AGP bus. This can increase performance
1758 of image write operations 2.5 times or more. Saying Y here creates a
1759 /proc/mtrr file which may be used to manipulate your processor's
1760 MTRRs. Typically the X server should use this.
1762 This code has a reasonably generic interface so that similar
1763 control registers on other processors can be easily supported
1766 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1767 Registers (ARRs) which provide a similar functionality to MTRRs. For
1768 these, the ARRs are used to emulate the MTRRs.
1769 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1770 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1771 write-combining. All of these processors are supported by this code
1772 and it makes sense to say Y here if you have one of them.
1774 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1775 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1776 can lead to all sorts of problems, so it's good to say Y here.
1778 You can safely say Y even if your machine doesn't have MTRRs, you'll
1779 just add about 9 KB to your kernel.
1781 See <file:Documentation/x86/mtrr.rst> for more information.
1783 config MTRR_SANITIZER
1785 prompt "MTRR cleanup support"
1788 Convert MTRR layout from continuous to discrete, so X drivers can
1789 add writeback entries.
1791 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1792 The largest mtrr entry size for a continuous block can be set with
1797 config MTRR_SANITIZER_ENABLE_DEFAULT
1798 int "MTRR cleanup enable value (0-1)"
1801 depends on MTRR_SANITIZER
1803 Enable mtrr cleanup default value
1805 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1806 int "MTRR cleanup spare reg num (0-7)"
1809 depends on MTRR_SANITIZER
1811 mtrr cleanup spare entries default, it can be changed via
1812 mtrr_spare_reg_nr=N on the kernel command line.
1816 prompt "x86 PAT support" if EXPERT
1819 Use PAT attributes to setup page level cache control.
1821 PATs are the modern equivalents of MTRRs and are much more
1822 flexible than MTRRs.
1824 Say N here if you see bootup problems (boot crash, boot hang,
1825 spontaneous reboots) or a non-working video driver.
1829 config ARCH_USES_PG_UNCACHED
1835 prompt "x86 architectural random number generator" if EXPERT
1837 Enable the x86 architectural RDRAND instruction
1838 (Intel Bull Mountain technology) to generate random numbers.
1839 If supported, this is a high bandwidth, cryptographically
1840 secure hardware random number generator.
1844 prompt "Supervisor Mode Access Prevention" if EXPERT
1846 Supervisor Mode Access Prevention (SMAP) is a security
1847 feature in newer Intel processors. There is a small
1848 performance cost if this enabled and turned on; there is
1849 also a small increase in the kernel size if this is enabled.
1855 prompt "User Mode Instruction Prevention" if EXPERT
1857 User Mode Instruction Prevention (UMIP) is a security feature in
1858 some x86 processors. If enabled, a general protection fault is
1859 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1860 executed in user mode. These instructions unnecessarily expose
1861 information about the hardware state.
1863 The vast majority of applications do not use these instructions.
1864 For the very few that do, software emulation is provided in
1865 specific cases in protected and virtual-8086 modes. Emulated
1868 config X86_INTEL_MEMORY_PROTECTION_KEYS
1869 prompt "Memory Protection Keys"
1871 # Note: only available in 64-bit mode
1872 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1873 select ARCH_USES_HIGH_VMA_FLAGS
1874 select ARCH_HAS_PKEYS
1876 Memory Protection Keys provides a mechanism for enforcing
1877 page-based protections, but without requiring modification of the
1878 page tables when an application changes protection domains.
1880 For details, see Documentation/core-api/protection-keys.rst
1885 prompt "TSX enable mode"
1886 depends on CPU_SUP_INTEL
1887 default X86_INTEL_TSX_MODE_OFF
1889 Intel's TSX (Transactional Synchronization Extensions) feature
1890 allows to optimize locking protocols through lock elision which
1891 can lead to a noticeable performance boost.
1893 On the other hand it has been shown that TSX can be exploited
1894 to form side channel attacks (e.g. TAA) and chances are there
1895 will be more of those attacks discovered in the future.
1897 Therefore TSX is not enabled by default (aka tsx=off). An admin
1898 might override this decision by tsx=on the command line parameter.
1899 Even with TSX enabled, the kernel will attempt to enable the best
1900 possible TAA mitigation setting depending on the microcode available
1901 for the particular machine.
1903 This option allows to set the default tsx mode between tsx=on, =off
1904 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1907 Say off if not sure, auto if TSX is in use but it should be used on safe
1908 platforms or on if TSX is in use and the security aspect of tsx is not
1911 config X86_INTEL_TSX_MODE_OFF
1914 TSX is disabled if possible - equals to tsx=off command line parameter.
1916 config X86_INTEL_TSX_MODE_ON
1919 TSX is always enabled on TSX capable HW - equals the tsx=on command
1922 config X86_INTEL_TSX_MODE_AUTO
1925 TSX is enabled on TSX capable HW that is believed to be safe against
1926 side channel attacks- equals the tsx=auto command line parameter.
1930 bool "EFI runtime service support"
1933 select EFI_RUNTIME_WRAPPERS
1935 This enables the kernel to use EFI runtime services that are
1936 available (such as the EFI variable services).
1938 This option is only useful on systems that have EFI firmware.
1939 In addition, you should use the latest ELILO loader available
1940 at <http://elilo.sourceforge.net> in order to take advantage
1941 of EFI runtime services. However, even with this option, the
1942 resultant kernel should continue to boot on existing non-EFI
1946 bool "EFI stub support"
1947 depends on EFI && !X86_USE_3DNOW
1948 depends on $(cc-option,-mabi=ms) || X86_32
1951 This kernel feature allows a bzImage to be loaded directly
1952 by EFI firmware without the use of a bootloader.
1954 See Documentation/admin-guide/efi-stub.rst for more information.
1957 bool "EFI mixed-mode support"
1958 depends on EFI_STUB && X86_64
1960 Enabling this feature allows a 64-bit kernel to be booted
1961 on a 32-bit firmware, provided that your CPU supports 64-bit
1964 Note that it is not possible to boot a mixed-mode enabled
1965 kernel via the EFI boot stub - a bootloader that supports
1966 the EFI handover protocol must be used.
1972 prompt "Enable seccomp to safely compute untrusted bytecode"
1974 This kernel feature is useful for number crunching applications
1975 that may need to compute untrusted bytecode during their
1976 execution. By using pipes or other transports made available to
1977 the process as file descriptors supporting the read/write
1978 syscalls, it's possible to isolate those applications in
1979 their own address space using seccomp. Once seccomp is
1980 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1981 and the task is only allowed to execute a few safe syscalls
1982 defined by each seccomp mode.
1984 If unsure, say Y. Only embedded should say N here.
1986 source "kernel/Kconfig.hz"
1989 bool "kexec system call"
1992 kexec is a system call that implements the ability to shutdown your
1993 current kernel, and to start another kernel. It is like a reboot
1994 but it is independent of the system firmware. And like a reboot
1995 you can start any kernel with it, not just Linux.
1997 The name comes from the similarity to the exec system call.
1999 It is an ongoing process to be certain the hardware in a machine
2000 is properly shutdown, so do not be surprised if this code does not
2001 initially work for you. As of this writing the exact hardware
2002 interface is strongly in flux, so no good recommendation can be
2006 bool "kexec file based system call"
2011 depends on CRYPTO_SHA256=y
2013 This is new version of kexec system call. This system call is
2014 file based and takes file descriptors as system call argument
2015 for kernel and initramfs as opposed to list of segments as
2016 accepted by previous system call.
2018 config ARCH_HAS_KEXEC_PURGATORY
2022 bool "Verify kernel signature during kexec_file_load() syscall"
2023 depends on KEXEC_FILE
2026 This option makes the kexec_file_load() syscall check for a valid
2027 signature of the kernel image. The image can still be loaded without
2028 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2029 there's a signature that we can check, then it must be valid.
2031 In addition to this option, you need to enable signature
2032 verification for the corresponding kernel image type being
2033 loaded in order for this to work.
2035 config KEXEC_SIG_FORCE
2036 bool "Require a valid signature in kexec_file_load() syscall"
2037 depends on KEXEC_SIG
2039 This option makes kernel signature verification mandatory for
2040 the kexec_file_load() syscall.
2042 config KEXEC_BZIMAGE_VERIFY_SIG
2043 bool "Enable bzImage signature verification support"
2044 depends on KEXEC_SIG
2045 depends on SIGNED_PE_FILE_VERIFICATION
2046 select SYSTEM_TRUSTED_KEYRING
2048 Enable bzImage signature verification support.
2051 bool "kernel crash dumps"
2052 depends on X86_64 || (X86_32 && HIGHMEM)
2054 Generate crash dump after being started by kexec.
2055 This should be normally only set in special crash dump kernels
2056 which are loaded in the main kernel with kexec-tools into
2057 a specially reserved region and then later executed after
2058 a crash by kdump/kexec. The crash dump kernel must be compiled
2059 to a memory address not used by the main kernel or BIOS using
2060 PHYSICAL_START, or it must be built as a relocatable image
2061 (CONFIG_RELOCATABLE=y).
2062 For more details see Documentation/admin-guide/kdump/kdump.rst
2066 depends on KEXEC && HIBERNATION
2068 Jump between original kernel and kexeced kernel and invoke
2069 code in physical address mode via KEXEC
2071 config PHYSICAL_START
2072 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2075 This gives the physical address where the kernel is loaded.
2077 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2078 bzImage will decompress itself to above physical address and
2079 run from there. Otherwise, bzImage will run from the address where
2080 it has been loaded by the boot loader and will ignore above physical
2083 In normal kdump cases one does not have to set/change this option
2084 as now bzImage can be compiled as a completely relocatable image
2085 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2086 address. This option is mainly useful for the folks who don't want
2087 to use a bzImage for capturing the crash dump and want to use a
2088 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2089 to be specifically compiled to run from a specific memory area
2090 (normally a reserved region) and this option comes handy.
2092 So if you are using bzImage for capturing the crash dump,
2093 leave the value here unchanged to 0x1000000 and set
2094 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2095 for capturing the crash dump change this value to start of
2096 the reserved region. In other words, it can be set based on
2097 the "X" value as specified in the "crashkernel=YM@XM"
2098 command line boot parameter passed to the panic-ed
2099 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2100 for more details about crash dumps.
2102 Usage of bzImage for capturing the crash dump is recommended as
2103 one does not have to build two kernels. Same kernel can be used
2104 as production kernel and capture kernel. Above option should have
2105 gone away after relocatable bzImage support is introduced. But it
2106 is present because there are users out there who continue to use
2107 vmlinux for dump capture. This option should go away down the
2110 Don't change this unless you know what you are doing.
2113 bool "Build a relocatable kernel"
2116 This builds a kernel image that retains relocation information
2117 so it can be loaded someplace besides the default 1MB.
2118 The relocations tend to make the kernel binary about 10% larger,
2119 but are discarded at runtime.
2121 One use is for the kexec on panic case where the recovery kernel
2122 must live at a different physical address than the primary
2125 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2126 it has been loaded at and the compile time physical address
2127 (CONFIG_PHYSICAL_START) is used as the minimum location.
2129 config RANDOMIZE_BASE
2130 bool "Randomize the address of the kernel image (KASLR)"
2131 depends on RELOCATABLE
2134 In support of Kernel Address Space Layout Randomization (KASLR),
2135 this randomizes the physical address at which the kernel image
2136 is decompressed and the virtual address where the kernel
2137 image is mapped, as a security feature that deters exploit
2138 attempts relying on knowledge of the location of kernel
2141 On 64-bit, the kernel physical and virtual addresses are
2142 randomized separately. The physical address will be anywhere
2143 between 16MB and the top of physical memory (up to 64TB). The
2144 virtual address will be randomized from 16MB up to 1GB (9 bits
2145 of entropy). Note that this also reduces the memory space
2146 available to kernel modules from 1.5GB to 1GB.
2148 On 32-bit, the kernel physical and virtual addresses are
2149 randomized together. They will be randomized from 16MB up to
2150 512MB (8 bits of entropy).
2152 Entropy is generated using the RDRAND instruction if it is
2153 supported. If RDTSC is supported, its value is mixed into
2154 the entropy pool as well. If neither RDRAND nor RDTSC are
2155 supported, then entropy is read from the i8254 timer. The
2156 usable entropy is limited by the kernel being built using
2157 2GB addressing, and that PHYSICAL_ALIGN must be at a
2158 minimum of 2MB. As a result, only 10 bits of entropy are
2159 theoretically possible, but the implementations are further
2160 limited due to memory layouts.
2164 # Relocation on x86 needs some additional build support
2165 config X86_NEED_RELOCS
2167 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2169 config PHYSICAL_ALIGN
2170 hex "Alignment value to which kernel should be aligned"
2172 range 0x2000 0x1000000 if X86_32
2173 range 0x200000 0x1000000 if X86_64
2175 This value puts the alignment restrictions on physical address
2176 where kernel is loaded and run from. Kernel is compiled for an
2177 address which meets above alignment restriction.
2179 If bootloader loads the kernel at a non-aligned address and
2180 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2181 address aligned to above value and run from there.
2183 If bootloader loads the kernel at a non-aligned address and
2184 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2185 load address and decompress itself to the address it has been
2186 compiled for and run from there. The address for which kernel is
2187 compiled already meets above alignment restrictions. Hence the
2188 end result is that kernel runs from a physical address meeting
2189 above alignment restrictions.
2191 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2192 this value must be a multiple of 0x200000.
2194 Don't change this unless you know what you are doing.
2196 config DYNAMIC_MEMORY_LAYOUT
2199 This option makes base addresses of vmalloc and vmemmap as well as
2200 __PAGE_OFFSET movable during boot.
2202 config RANDOMIZE_MEMORY
2203 bool "Randomize the kernel memory sections"
2205 depends on RANDOMIZE_BASE
2206 select DYNAMIC_MEMORY_LAYOUT
2207 default RANDOMIZE_BASE
2209 Randomizes the base virtual address of kernel memory sections
2210 (physical memory mapping, vmalloc & vmemmap). This security feature
2211 makes exploits relying on predictable memory locations less reliable.
2213 The order of allocations remains unchanged. Entropy is generated in
2214 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2215 configuration have in average 30,000 different possible virtual
2216 addresses for each memory section.
2220 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2221 hex "Physical memory mapping padding" if EXPERT
2222 depends on RANDOMIZE_MEMORY
2223 default "0xa" if MEMORY_HOTPLUG
2225 range 0x1 0x40 if MEMORY_HOTPLUG
2228 Define the padding in terabytes added to the existing physical
2229 memory size during kernel memory randomization. It is useful
2230 for memory hotplug support but reduces the entropy available for
2231 address randomization.
2233 If unsure, leave at the default value.
2239 config BOOTPARAM_HOTPLUG_CPU0
2240 bool "Set default setting of cpu0_hotpluggable"
2241 depends on HOTPLUG_CPU
2243 Set whether default state of cpu0_hotpluggable is on or off.
2245 Say Y here to enable CPU0 hotplug by default. If this switch
2246 is turned on, there is no need to give cpu0_hotplug kernel
2247 parameter and the CPU0 hotplug feature is enabled by default.
2249 Please note: there are two known CPU0 dependencies if you want
2250 to enable the CPU0 hotplug feature either by this switch or by
2251 cpu0_hotplug kernel parameter.
2253 First, resume from hibernate or suspend always starts from CPU0.
2254 So hibernate and suspend are prevented if CPU0 is offline.
2256 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2257 offline if any interrupt can not migrate out of CPU0. There may
2258 be other CPU0 dependencies.
2260 Please make sure the dependencies are under your control before
2261 you enable this feature.
2263 Say N if you don't want to enable CPU0 hotplug feature by default.
2264 You still can enable the CPU0 hotplug feature at boot by kernel
2265 parameter cpu0_hotplug.
2267 config DEBUG_HOTPLUG_CPU0
2269 prompt "Debug CPU0 hotplug"
2270 depends on HOTPLUG_CPU
2272 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2273 soon as possible and boots up userspace with CPU0 offlined. User
2274 can online CPU0 back after boot time.
2276 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2277 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2278 compilation or giving cpu0_hotplug kernel parameter at boot.
2284 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2285 depends on COMPAT_32
2287 Certain buggy versions of glibc will crash if they are
2288 presented with a 32-bit vDSO that is not mapped at the address
2289 indicated in its segment table.
2291 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2292 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2293 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2294 the only released version with the bug, but OpenSUSE 9
2295 contains a buggy "glibc 2.3.2".
2297 The symptom of the bug is that everything crashes on startup, saying:
2298 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2300 Saying Y here changes the default value of the vdso32 boot
2301 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2302 This works around the glibc bug but hurts performance.
2304 If unsure, say N: if you are compiling your own kernel, you
2305 are unlikely to be using a buggy version of glibc.
2308 prompt "vsyscall table for legacy applications"
2310 default LEGACY_VSYSCALL_XONLY
2312 Legacy user code that does not know how to find the vDSO expects
2313 to be able to issue three syscalls by calling fixed addresses in
2314 kernel space. Since this location is not randomized with ASLR,
2315 it can be used to assist security vulnerability exploitation.
2317 This setting can be changed at boot time via the kernel command
2318 line parameter vsyscall=[emulate|xonly|none].
2320 On a system with recent enough glibc (2.14 or newer) and no
2321 static binaries, you can say None without a performance penalty
2322 to improve security.
2324 If unsure, select "Emulate execution only".
2326 config LEGACY_VSYSCALL_EMULATE
2327 bool "Full emulation"
2329 The kernel traps and emulates calls into the fixed vsyscall
2330 address mapping. This makes the mapping non-executable, but
2331 it still contains readable known contents, which could be
2332 used in certain rare security vulnerability exploits. This
2333 configuration is recommended when using legacy userspace
2334 that still uses vsyscalls along with legacy binary
2335 instrumentation tools that require code to be readable.
2337 An example of this type of legacy userspace is running
2338 Pin on an old binary that still uses vsyscalls.
2340 config LEGACY_VSYSCALL_XONLY
2341 bool "Emulate execution only"
2343 The kernel traps and emulates calls into the fixed vsyscall
2344 address mapping and does not allow reads. This
2345 configuration is recommended when userspace might use the
2346 legacy vsyscall area but support for legacy binary
2347 instrumentation of legacy code is not needed. It mitigates
2348 certain uses of the vsyscall area as an ASLR-bypassing
2351 config LEGACY_VSYSCALL_NONE
2354 There will be no vsyscall mapping at all. This will
2355 eliminate any risk of ASLR bypass due to the vsyscall
2356 fixed address mapping. Attempts to use the vsyscalls
2357 will be reported to dmesg, so that either old or
2358 malicious userspace programs can be identified.
2363 bool "Built-in kernel command line"
2365 Allow for specifying boot arguments to the kernel at
2366 build time. On some systems (e.g. embedded ones), it is
2367 necessary or convenient to provide some or all of the
2368 kernel boot arguments with the kernel itself (that is,
2369 to not rely on the boot loader to provide them.)
2371 To compile command line arguments into the kernel,
2372 set this option to 'Y', then fill in the
2373 boot arguments in CONFIG_CMDLINE.
2375 Systems with fully functional boot loaders (i.e. non-embedded)
2376 should leave this option set to 'N'.
2379 string "Built-in kernel command string"
2380 depends on CMDLINE_BOOL
2383 Enter arguments here that should be compiled into the kernel
2384 image and used at boot time. If the boot loader provides a
2385 command line at boot time, it is appended to this string to
2386 form the full kernel command line, when the system boots.
2388 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2389 change this behavior.
2391 In most cases, the command line (whether built-in or provided
2392 by the boot loader) should specify the device for the root
2395 config CMDLINE_OVERRIDE
2396 bool "Built-in command line overrides boot loader arguments"
2397 depends on CMDLINE_BOOL && CMDLINE != ""
2399 Set this option to 'Y' to have the kernel ignore the boot loader
2400 command line, and use ONLY the built-in command line.
2402 This is used to work around broken boot loaders. This should
2403 be set to 'N' under normal conditions.
2405 config MODIFY_LDT_SYSCALL
2406 bool "Enable the LDT (local descriptor table)" if EXPERT
2409 Linux can allow user programs to install a per-process x86
2410 Local Descriptor Table (LDT) using the modify_ldt(2) system
2411 call. This is required to run 16-bit or segmented code such as
2412 DOSEMU or some Wine programs. It is also used by some very old
2413 threading libraries.
2415 Enabling this feature adds a small amount of overhead to
2416 context switches and increases the low-level kernel attack
2417 surface. Disabling it removes the modify_ldt(2) system call.
2419 Saying 'N' here may make sense for embedded or server kernels.
2421 source "kernel/livepatch/Kconfig"
2425 config ARCH_HAS_ADD_PAGES
2427 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2429 config ARCH_ENABLE_MEMORY_HOTPLUG
2431 depends on X86_64 || (X86_32 && HIGHMEM)
2433 config ARCH_ENABLE_MEMORY_HOTREMOVE
2435 depends on MEMORY_HOTPLUG
2437 config USE_PERCPU_NUMA_NODE_ID
2441 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2443 depends on X86_64 || X86_PAE
2445 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2447 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2449 config ARCH_ENABLE_THP_MIGRATION
2451 depends on X86_64 && TRANSPARENT_HUGEPAGE
2453 menu "Power management and ACPI options"
2455 config ARCH_HIBERNATION_HEADER
2457 depends on HIBERNATION
2459 source "kernel/power/Kconfig"
2461 source "drivers/acpi/Kconfig"
2463 source "drivers/sfi/Kconfig"
2470 tristate "APM (Advanced Power Management) BIOS support"
2471 depends on X86_32 && PM_SLEEP
2473 APM is a BIOS specification for saving power using several different
2474 techniques. This is mostly useful for battery powered laptops with
2475 APM compliant BIOSes. If you say Y here, the system time will be
2476 reset after a RESUME operation, the /proc/apm device will provide
2477 battery status information, and user-space programs will receive
2478 notification of APM "events" (e.g. battery status change).
2480 If you select "Y" here, you can disable actual use of the APM
2481 BIOS by passing the "apm=off" option to the kernel at boot time.
2483 Note that the APM support is almost completely disabled for
2484 machines with more than one CPU.
2486 In order to use APM, you will need supporting software. For location
2487 and more information, read <file:Documentation/power/apm-acpi.rst>
2488 and the Battery Powered Linux mini-HOWTO, available from
2489 <http://www.tldp.org/docs.html#howto>.
2491 This driver does not spin down disk drives (see the hdparm(8)
2492 manpage ("man 8 hdparm") for that), and it doesn't turn off
2493 VESA-compliant "green" monitors.
2495 This driver does not support the TI 4000M TravelMate and the ACER
2496 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2497 desktop machines also don't have compliant BIOSes, and this driver
2498 may cause those machines to panic during the boot phase.
2500 Generally, if you don't have a battery in your machine, there isn't
2501 much point in using this driver and you should say N. If you get
2502 random kernel OOPSes or reboots that don't seem to be related to
2503 anything, try disabling/enabling this option (or disabling/enabling
2506 Some other things you should try when experiencing seemingly random,
2509 1) make sure that you have enough swap space and that it is
2511 2) pass the "no-hlt" option to the kernel
2512 3) switch on floating point emulation in the kernel and pass
2513 the "no387" option to the kernel
2514 4) pass the "floppy=nodma" option to the kernel
2515 5) pass the "mem=4M" option to the kernel (thereby disabling
2516 all but the first 4 MB of RAM)
2517 6) make sure that the CPU is not over clocked.
2518 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2519 8) disable the cache from your BIOS settings
2520 9) install a fan for the video card or exchange video RAM
2521 10) install a better fan for the CPU
2522 11) exchange RAM chips
2523 12) exchange the motherboard.
2525 To compile this driver as a module, choose M here: the
2526 module will be called apm.
2530 config APM_IGNORE_USER_SUSPEND
2531 bool "Ignore USER SUSPEND"
2533 This option will ignore USER SUSPEND requests. On machines with a
2534 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2535 series notebooks, it is necessary to say Y because of a BIOS bug.
2537 config APM_DO_ENABLE
2538 bool "Enable PM at boot time"
2540 Enable APM features at boot time. From page 36 of the APM BIOS
2541 specification: "When disabled, the APM BIOS does not automatically
2542 power manage devices, enter the Standby State, enter the Suspend
2543 State, or take power saving steps in response to CPU Idle calls."
2544 This driver will make CPU Idle calls when Linux is idle (unless this
2545 feature is turned off -- see "Do CPU IDLE calls", below). This
2546 should always save battery power, but more complicated APM features
2547 will be dependent on your BIOS implementation. You may need to turn
2548 this option off if your computer hangs at boot time when using APM
2549 support, or if it beeps continuously instead of suspending. Turn
2550 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2551 T400CDT. This is off by default since most machines do fine without
2556 bool "Make CPU Idle calls when idle"
2558 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2559 On some machines, this can activate improved power savings, such as
2560 a slowed CPU clock rate, when the machine is idle. These idle calls
2561 are made after the idle loop has run for some length of time (e.g.,
2562 333 mS). On some machines, this will cause a hang at boot time or
2563 whenever the CPU becomes idle. (On machines with more than one CPU,
2564 this option does nothing.)
2566 config APM_DISPLAY_BLANK
2567 bool "Enable console blanking using APM"
2569 Enable console blanking using the APM. Some laptops can use this to
2570 turn off the LCD backlight when the screen blanker of the Linux
2571 virtual console blanks the screen. Note that this is only used by
2572 the virtual console screen blanker, and won't turn off the backlight
2573 when using the X Window system. This also doesn't have anything to
2574 do with your VESA-compliant power-saving monitor. Further, this
2575 option doesn't work for all laptops -- it might not turn off your
2576 backlight at all, or it might print a lot of errors to the console,
2577 especially if you are using gpm.
2579 config APM_ALLOW_INTS
2580 bool "Allow interrupts during APM BIOS calls"
2582 Normally we disable external interrupts while we are making calls to
2583 the APM BIOS as a measure to lessen the effects of a badly behaving
2584 BIOS implementation. The BIOS should reenable interrupts if it
2585 needs to. Unfortunately, some BIOSes do not -- especially those in
2586 many of the newer IBM Thinkpads. If you experience hangs when you
2587 suspend, try setting this to Y. Otherwise, say N.
2591 source "drivers/cpufreq/Kconfig"
2593 source "drivers/cpuidle/Kconfig"
2595 source "drivers/idle/Kconfig"
2600 menu "Bus options (PCI etc.)"
2603 prompt "PCI access mode"
2604 depends on X86_32 && PCI
2607 On PCI systems, the BIOS can be used to detect the PCI devices and
2608 determine their configuration. However, some old PCI motherboards
2609 have BIOS bugs and may crash if this is done. Also, some embedded
2610 PCI-based systems don't have any BIOS at all. Linux can also try to
2611 detect the PCI hardware directly without using the BIOS.
2613 With this option, you can specify how Linux should detect the
2614 PCI devices. If you choose "BIOS", the BIOS will be used,
2615 if you choose "Direct", the BIOS won't be used, and if you
2616 choose "MMConfig", then PCI Express MMCONFIG will be used.
2617 If you choose "Any", the kernel will try MMCONFIG, then the
2618 direct access method and falls back to the BIOS if that doesn't
2619 work. If unsure, go with the default, which is "Any".
2624 config PCI_GOMMCONFIG
2641 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2643 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2646 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2649 bool "Support mmconfig PCI config space access" if X86_64
2651 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2652 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2656 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2660 depends on PCI && XEN
2663 config MMCONF_FAM10H
2665 depends on X86_64 && PCI_MMCONFIG && ACPI
2667 config PCI_CNB20LE_QUIRK
2668 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2671 Read the PCI windows out of the CNB20LE host bridge. This allows
2672 PCI hotplug to work on systems with the CNB20LE chipset which do
2675 There's no public spec for this chipset, and this functionality
2676 is known to be incomplete.
2678 You should say N unless you know you need this.
2681 bool "ISA bus support on modern systems" if EXPERT
2683 Expose ISA bus device drivers and options available for selection and
2684 configuration. Enable this option if your target machine has an ISA
2685 bus. ISA is an older system, displaced by PCI and newer bus
2686 architectures -- if your target machine is modern, it probably does
2687 not have an ISA bus.
2691 # x86_64 have no ISA slots, but can have ISA-style DMA.
2693 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2696 Enables ISA-style DMA support for devices requiring such controllers.
2704 Find out whether you have ISA slots on your motherboard. ISA is the
2705 name of a bus system, i.e. the way the CPU talks to the other stuff
2706 inside your box. Other bus systems are PCI, EISA, MicroChannel
2707 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2708 newer boards don't support it. If you have ISA, say Y, otherwise N.
2711 tristate "NatSemi SCx200 support"
2713 This provides basic support for National Semiconductor's
2714 (now AMD's) Geode processors. The driver probes for the
2715 PCI-IDs of several on-chip devices, so its a good dependency
2716 for other scx200_* drivers.
2718 If compiled as a module, the driver is named scx200.
2720 config SCx200HR_TIMER
2721 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2725 This driver provides a clocksource built upon the on-chip
2726 27MHz high-resolution timer. Its also a workaround for
2727 NSC Geode SC-1100's buggy TSC, which loses time when the
2728 processor goes idle (as is done by the scheduler). The
2729 other workaround is idle=poll boot option.
2732 bool "One Laptop Per Child support"
2740 Add support for detecting the unique features of the OLPC
2744 bool "OLPC XO-1 Power Management"
2745 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2747 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2750 bool "OLPC XO-1 Real Time Clock"
2751 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2753 Add support for the XO-1 real time clock, which can be used as a
2754 programmable wakeup source.
2757 bool "OLPC XO-1 SCI extras"
2758 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2762 Add support for SCI-based features of the OLPC XO-1 laptop:
2763 - EC-driven system wakeups
2767 - AC adapter status updates
2768 - Battery status updates
2770 config OLPC_XO15_SCI
2771 bool "OLPC XO-1.5 SCI extras"
2772 depends on OLPC && ACPI
2775 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2776 - EC-driven system wakeups
2777 - AC adapter status updates
2778 - Battery status updates
2781 bool "PCEngines ALIX System Support (LED setup)"
2784 This option enables system support for the PCEngines ALIX.
2785 At present this just sets up LEDs for GPIO control on
2786 ALIX2/3/6 boards. However, other system specific setup should
2789 Note: You must still enable the drivers for GPIO and LED support
2790 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2792 Note: You have to set alix.force=1 for boards with Award BIOS.
2795 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2798 This option enables system support for the Soekris Engineering net5501.
2801 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2805 This option enables system support for the Traverse Technologies GEOS.
2808 bool "Technologic Systems TS-5500 platform support"
2810 select CHECK_SIGNATURE
2814 This option enables system support for the Technologic Systems TS-5500.
2820 depends on CPU_SUP_AMD && PCI
2823 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2825 Firmwares often provide initial graphics framebuffers so the BIOS,
2826 bootloader or kernel can show basic video-output during boot for
2827 user-guidance and debugging. Historically, x86 used the VESA BIOS
2828 Extensions and EFI-framebuffers for this, which are mostly limited
2830 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2831 framebuffers so the new generic system-framebuffer drivers can be
2832 used on x86. If the framebuffer is not compatible with the generic
2833 modes, it is advertised as fallback platform framebuffer so legacy
2834 drivers like efifb, vesafb and uvesafb can pick it up.
2835 If this option is not selected, all system framebuffers are always
2836 marked as fallback platform framebuffers as usual.
2838 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2839 not be able to pick up generic system framebuffers if this option
2840 is selected. You are highly encouraged to enable simplefb as
2841 replacement if you select this option. simplefb can correctly deal
2842 with generic system framebuffers. But you should still keep vesafb
2843 and others enabled as fallback if a system framebuffer is
2844 incompatible with simplefb.
2851 menu "Binary Emulations"
2853 config IA32_EMULATION
2854 bool "IA32 Emulation"
2856 select ARCH_WANT_OLD_COMPAT_IPC
2858 select COMPAT_BINFMT_ELF
2859 select COMPAT_OLD_SIGACTION
2861 Include code to run legacy 32-bit programs under a
2862 64-bit kernel. You should likely turn this on, unless you're
2863 100% sure that you don't have any 32-bit programs left.
2866 tristate "IA32 a.out support"
2867 depends on IA32_EMULATION
2870 Support old a.out binaries in the 32bit emulation.
2873 bool "x32 ABI for 64-bit mode"
2876 Include code to run binaries for the x32 native 32-bit ABI
2877 for 64-bit processors. An x32 process gets access to the
2878 full 64-bit register file and wide data path while leaving
2879 pointers at 32 bits for smaller memory footprint.
2881 You will need a recent binutils (2.22 or later) with
2882 elf32_x86_64 support enabled to compile a kernel with this
2887 depends on IA32_EMULATION || X86_32
2889 select OLD_SIGSUSPEND3
2893 depends on IA32_EMULATION || X86_X32
2896 config COMPAT_FOR_U64_ALIGNMENT
2899 config SYSVIPC_COMPAT
2907 config HAVE_ATOMIC_IOMAP
2911 source "drivers/firmware/Kconfig"
2913 source "arch/x86/kvm/Kconfig"
2915 source "arch/x86/Kconfig.assembler"