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 GENERIC_VDSO_32
18 select HAVE_DEBUG_STACKOVERFLOW
20 select MODULES_USE_ELF_REL
22 select ARCH_SPLIT_ARG64
27 # Options that are inherently 64-bit kernel only:
28 select ARCH_HAS_GIGANTIC_PAGE
29 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
30 select ARCH_USE_CMPXCHG_LOCKREF
31 select HAVE_ARCH_SOFT_DIRTY
32 select MODULES_USE_ELF_RELA
33 select NEED_DMA_MAP_STATE
36 config FORCE_DYNAMIC_FTRACE
39 depends on FUNCTION_TRACER
42 We keep the static function tracing (!DYNAMIC_FTRACE) around
43 in order to test the non static function tracing in the
44 generic code, as other architectures still use it. But we
45 only need to keep it around for x86_64. No need to keep it
46 for x86_32. For x86_32, force DYNAMIC_FTRACE.
50 # ( Note that options that are marked 'if X86_64' could in principle be
51 # ported to 32-bit as well. )
56 # Note: keep this list sorted alphabetically
58 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
59 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
60 select ARCH_32BIT_OFF_T if X86_32
61 select ARCH_CLOCKSOURCE_INIT
62 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
63 select ARCH_HAS_DEBUG_VIRTUAL
64 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
65 select ARCH_HAS_DEVMEM_IS_ALLOWED
66 select ARCH_HAS_EARLY_DEBUG if KGDB
67 select ARCH_HAS_ELF_RANDOMIZE
68 select ARCH_HAS_FAST_MULTIPLIER
69 select ARCH_HAS_FILTER_PGPROT
70 select ARCH_HAS_FORTIFY_SOURCE
71 select ARCH_HAS_GCOV_PROFILE_ALL
72 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
73 select ARCH_HAS_MEM_ENCRYPT
74 select ARCH_HAS_MEMBARRIER_SYNC_CORE
75 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
76 select ARCH_HAS_PMEM_API if X86_64
77 select ARCH_HAS_PTE_DEVMAP if X86_64
78 select ARCH_HAS_PTE_SPECIAL
79 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
80 select ARCH_HAS_COPY_MC if X86_64
81 select ARCH_HAS_SET_MEMORY
82 select ARCH_HAS_SET_DIRECT_MAP
83 select ARCH_HAS_STRICT_KERNEL_RWX
84 select ARCH_HAS_STRICT_MODULE_RWX
85 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
86 select ARCH_HAS_SYSCALL_WRAPPER
87 select ARCH_HAS_UBSAN_SANITIZE_ALL
88 select ARCH_HAS_DEBUG_WX
89 select ARCH_HAVE_NMI_SAFE_CMPXCHG
90 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
91 select ARCH_MIGHT_HAVE_PC_PARPORT
92 select ARCH_MIGHT_HAVE_PC_SERIO
94 select ARCH_SUPPORTS_ACPI
95 select ARCH_SUPPORTS_ATOMIC_RMW
96 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
97 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
98 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
99 select ARCH_USE_BUILTIN_BSWAP
100 select ARCH_USE_QUEUED_RWLOCKS
101 select ARCH_USE_QUEUED_SPINLOCKS
102 select ARCH_USE_SYM_ANNOTATIONS
103 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
104 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
105 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
106 select ARCH_WANT_HUGE_PMD_SHARE
107 select ARCH_WANT_LD_ORPHAN_WARN
108 select ARCH_WANTS_THP_SWAP if X86_64
109 select BUILDTIME_TABLE_SORT
111 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
112 select CLOCKSOURCE_WATCHDOG
113 select DCACHE_WORD_ACCESS
114 select EDAC_ATOMIC_SCRUB
116 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
117 select GENERIC_CLOCKEVENTS_MIN_ADJUST
118 select GENERIC_CMOS_UPDATE
119 select GENERIC_CPU_AUTOPROBE
120 select GENERIC_CPU_VULNERABILITIES
121 select GENERIC_EARLY_IOREMAP
123 select GENERIC_FIND_FIRST_BIT
125 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
126 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
127 select GENERIC_IRQ_MIGRATION if SMP
128 select GENERIC_IRQ_PROBE
129 select GENERIC_IRQ_RESERVATION_MODE
130 select GENERIC_IRQ_SHOW
131 select GENERIC_PENDING_IRQ if SMP
132 select GENERIC_PTDUMP
133 select GENERIC_SMP_IDLE_THREAD
134 select GENERIC_STRNCPY_FROM_USER
135 select GENERIC_STRNLEN_USER
136 select GENERIC_TIME_VSYSCALL
137 select GENERIC_GETTIMEOFDAY
138 select GENERIC_VDSO_TIME_NS
139 select GUP_GET_PTE_LOW_HIGH if X86_PAE
140 select HARDIRQS_SW_RESEND
141 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
142 select HAVE_ACPI_APEI if ACPI
143 select HAVE_ACPI_APEI_NMI if ACPI
144 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
145 select HAVE_ARCH_AUDITSYSCALL
146 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
147 select HAVE_ARCH_JUMP_LABEL
148 select HAVE_ARCH_JUMP_LABEL_RELATIVE
149 select HAVE_ARCH_KASAN if X86_64
150 select HAVE_ARCH_KASAN_VMALLOC if X86_64
151 select HAVE_ARCH_KGDB
152 select HAVE_ARCH_MMAP_RND_BITS if MMU
153 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
154 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
155 select HAVE_ARCH_PREL32_RELOCATIONS
156 select HAVE_ARCH_SECCOMP_FILTER
157 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
158 select HAVE_ARCH_STACKLEAK
159 select HAVE_ARCH_TRACEHOOK
160 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
161 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
162 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
163 select HAVE_ARCH_VMAP_STACK if X86_64
164 select HAVE_ARCH_WITHIN_STACK_FRAMES
165 select HAVE_ASM_MODVERSIONS
166 select HAVE_CMPXCHG_DOUBLE
167 select HAVE_CMPXCHG_LOCAL
168 select HAVE_CONTEXT_TRACKING if X86_64
169 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
170 select HAVE_C_RECORDMCOUNT
171 select HAVE_DEBUG_KMEMLEAK
172 select HAVE_DMA_CONTIGUOUS
173 select HAVE_DYNAMIC_FTRACE
174 select HAVE_DYNAMIC_FTRACE_WITH_REGS
175 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
176 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
178 select HAVE_EFFICIENT_UNALIGNED_ACCESS
180 select HAVE_EXIT_THREAD
182 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
183 select HAVE_FTRACE_MCOUNT_RECORD
184 select HAVE_FUNCTION_GRAPH_TRACER
185 select HAVE_FUNCTION_TRACER
186 select HAVE_GCC_PLUGINS
187 select HAVE_HW_BREAKPOINT
189 select HAVE_IOREMAP_PROT
190 select HAVE_IRQ_TIME_ACCOUNTING
191 select HAVE_KERNEL_BZIP2
192 select HAVE_KERNEL_GZIP
193 select HAVE_KERNEL_LZ4
194 select HAVE_KERNEL_LZMA
195 select HAVE_KERNEL_LZO
196 select HAVE_KERNEL_XZ
197 select HAVE_KERNEL_ZSTD
199 select HAVE_KPROBES_ON_FTRACE
200 select HAVE_FUNCTION_ERROR_INJECTION
201 select HAVE_KRETPROBES
203 select HAVE_LIVEPATCH if X86_64
204 select HAVE_MIXED_BREAKPOINTS_REGS
205 select HAVE_MOD_ARCH_SPECIFIC
210 select HAVE_OPTPROBES
211 select HAVE_PCSPKR_PLATFORM
212 select HAVE_PERF_EVENTS
213 select HAVE_PERF_EVENTS_NMI
214 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
216 select HAVE_PERF_REGS
217 select HAVE_PERF_USER_STACK_DUMP
218 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
219 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
220 select HAVE_REGS_AND_STACK_ACCESS_API
221 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
222 select HAVE_FUNCTION_ARG_ACCESS_API
223 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
224 select HAVE_STACK_VALIDATION if X86_64
225 select HAVE_STATIC_CALL
226 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
228 select HAVE_SYSCALL_TRACEPOINTS
229 select HAVE_UNSTABLE_SCHED_CLOCK
230 select HAVE_USER_RETURN_NOTIFIER
231 select HAVE_GENERIC_VDSO
232 select HOTPLUG_SMT if SMP
233 select IRQ_FORCED_THREADING
234 select NEED_SG_DMA_LENGTH
235 select PCI_DOMAINS if PCI
236 select PCI_LOCKLESS_CONFIG if PCI
239 select RTC_MC146818_LIB
242 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
243 select SYSCTL_EXCEPTION_TRACE
244 select THREAD_INFO_IN_TASK
245 select USER_STACKTRACE_SUPPORT
247 select HAVE_ARCH_KCSAN if X86_64
248 select X86_FEATURE_NAMES if PROC_FS
249 select PROC_PID_ARCH_STATUS if PROC_FS
250 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
252 config INSTRUCTION_DECODER
254 depends on KPROBES || PERF_EVENTS || UPROBES
258 default "elf32-i386" if X86_32
259 default "elf64-x86-64" if X86_64
261 config LOCKDEP_SUPPORT
264 config STACKTRACE_SUPPORT
270 config ARCH_MMAP_RND_BITS_MIN
274 config ARCH_MMAP_RND_BITS_MAX
278 config ARCH_MMAP_RND_COMPAT_BITS_MIN
281 config ARCH_MMAP_RND_COMPAT_BITS_MAX
287 config GENERIC_ISA_DMA
289 depends on ISA_DMA_API
294 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
296 config GENERIC_BUG_RELATIVE_POINTERS
299 config ARCH_MAY_HAVE_PC_FDC
301 depends on ISA_DMA_API
303 config GENERIC_CALIBRATE_DELAY
306 config ARCH_HAS_CPU_RELAX
309 config ARCH_HAS_CACHE_LINE_SIZE
312 config ARCH_HAS_FILTER_PGPROT
315 config HAVE_SETUP_PER_CPU_AREA
318 config NEED_PER_CPU_EMBED_FIRST_CHUNK
321 config NEED_PER_CPU_PAGE_FIRST_CHUNK
324 config ARCH_HIBERNATION_POSSIBLE
327 config ARCH_SUSPEND_POSSIBLE
330 config ARCH_WANT_GENERAL_HUGETLB
339 config KASAN_SHADOW_OFFSET
342 default 0xdffffc0000000000
344 config HAVE_INTEL_TXT
346 depends on INTEL_IOMMU && ACPI
350 depends on X86_32 && SMP
354 depends on X86_64 && SMP
356 config X86_32_LAZY_GS
358 depends on X86_32 && !STACKPROTECTOR
360 config ARCH_SUPPORTS_UPROBES
363 config FIX_EARLYCON_MEM
366 config DYNAMIC_PHYSICAL_MASK
369 config PGTABLE_LEVELS
371 default 5 if X86_5LEVEL
376 config CC_HAS_SANE_STACKPROTECTOR
378 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
379 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
381 We have to make sure stack protector is unconditionally disabled if
382 the compiler produces broken code.
384 menu "Processor type and features"
387 bool "DMA memory allocation support" if EXPERT
390 DMA memory allocation support allows devices with less than 32-bit
391 addressing to allocate within the first 16MB of address space.
392 Disable if no such devices will be used.
397 bool "Symmetric multi-processing support"
399 This enables support for systems with more than one CPU. If you have
400 a system with only one CPU, say N. If you have a system with more
403 If you say N here, the kernel will run on uni- and multiprocessor
404 machines, but will use only one CPU of a multiprocessor machine. If
405 you say Y here, the kernel will run on many, but not all,
406 uniprocessor machines. On a uniprocessor machine, the kernel
407 will run faster if you say N here.
409 Note that if you say Y here and choose architecture "586" or
410 "Pentium" under "Processor family", the kernel will not work on 486
411 architectures. Similarly, multiprocessor kernels for the "PPro"
412 architecture may not work on all Pentium based boards.
414 People using multiprocessor machines who say Y here should also say
415 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
416 Management" code will be disabled if you say Y here.
418 See also <file:Documentation/x86/i386/IO-APIC.rst>,
419 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
420 <http://www.tldp.org/docs.html#howto>.
422 If you don't know what to do here, say N.
424 config X86_FEATURE_NAMES
425 bool "Processor feature human-readable names" if EMBEDDED
428 This option compiles in a table of x86 feature bits and corresponding
429 names. This is required to support /proc/cpuinfo and a few kernel
430 messages. You can disable this to save space, at the expense of
431 making those few kernel messages show numeric feature bits instead.
436 bool "Support x2apic"
437 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
439 This enables x2apic support on CPUs that have this feature.
441 This allows 32-bit apic IDs (so it can support very large systems),
442 and accesses the local apic via MSRs not via mmio.
444 If you don't know what to do here, say N.
447 bool "Enable MPS table" if ACPI || SFI
449 depends on X86_LOCAL_APIC
451 For old smp systems that do not have proper acpi support. Newer systems
452 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
456 depends on X86_GOLDFISH
459 bool "Avoid speculative indirect branches in kernel"
462 Compile kernel with the retpoline compiler options to guard against
463 kernel-to-user data leaks by avoiding speculative indirect
464 branches. Requires a compiler with -mindirect-branch=thunk-extern
465 support for full protection. The kernel may run slower.
467 config X86_CPU_RESCTRL
468 bool "x86 CPU resource control support"
469 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
471 select PROC_CPU_RESCTRL if PROC_FS
473 Enable x86 CPU resource control support.
475 Provide support for the allocation and monitoring of system resources
478 Intel calls this Intel Resource Director Technology
479 (Intel(R) RDT). More information about RDT can be found in the
480 Intel x86 Architecture Software Developer Manual.
482 AMD calls this AMD Platform Quality of Service (AMD QoS).
483 More information about AMD QoS can be found in the AMD64 Technology
484 Platform Quality of Service Extensions manual.
490 bool "Support for big SMP systems with more than 8 CPUs"
493 This option is needed for the systems that have more than 8 CPUs.
495 config X86_EXTENDED_PLATFORM
496 bool "Support for extended (non-PC) x86 platforms"
499 If you disable this option then the kernel will only support
500 standard PC platforms. (which covers the vast majority of
503 If you enable this option then you'll be able to select support
504 for the following (non-PC) 32 bit x86 platforms:
505 Goldfish (Android emulator)
508 SGI 320/540 (Visual Workstation)
509 STA2X11-based (e.g. Northville)
510 Moorestown MID devices
512 If you have one of these systems, or if you want to build a
513 generic distribution kernel, say Y here - otherwise say N.
517 config X86_EXTENDED_PLATFORM
518 bool "Support for extended (non-PC) x86 platforms"
521 If you disable this option then the kernel will only support
522 standard PC platforms. (which covers the vast majority of
525 If you enable this option then you'll be able to select support
526 for the following (non-PC) 64 bit x86 platforms:
531 If you have one of these systems, or if you want to build a
532 generic distribution kernel, say Y here - otherwise say N.
534 # This is an alphabetically sorted list of 64 bit extended platforms
535 # Please maintain the alphabetic order if and when there are additions
537 bool "Numascale NumaChip"
539 depends on X86_EXTENDED_PLATFORM
542 depends on X86_X2APIC
543 depends on PCI_MMCONFIG
545 Adds support for Numascale NumaChip large-SMP systems. Needed to
546 enable more than ~168 cores.
547 If you don't have one of these, you should say N here.
551 select HYPERVISOR_GUEST
553 depends on X86_64 && PCI
554 depends on X86_EXTENDED_PLATFORM
557 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
558 supposed to run on these EM64T-based machines. Only choose this option
559 if you have one of these machines.
562 bool "SGI Ultraviolet"
564 depends on X86_EXTENDED_PLATFORM
567 depends on X86_X2APIC
570 This option is needed in order to support SGI Ultraviolet systems.
571 If you don't have one of these, you should say N here.
573 # Following is an alphabetically sorted list of 32 bit extended platforms
574 # Please maintain the alphabetic order if and when there are additions
577 bool "Goldfish (Virtual Platform)"
578 depends on X86_EXTENDED_PLATFORM
580 Enable support for the Goldfish virtual platform used primarily
581 for Android development. Unless you are building for the Android
582 Goldfish emulator say N here.
585 bool "CE4100 TV platform"
587 depends on PCI_GODIRECT
588 depends on X86_IO_APIC
590 depends on X86_EXTENDED_PLATFORM
591 select X86_REBOOTFIXUPS
593 select OF_EARLY_FLATTREE
595 Select for the Intel CE media processor (CE4100) SOC.
596 This option compiles in support for the CE4100 SOC for settop
597 boxes and media devices.
600 bool "Intel MID platform support"
601 depends on X86_EXTENDED_PLATFORM
602 depends on X86_PLATFORM_DEVICES
604 depends on X86_64 || (PCI_GOANY && X86_32)
605 depends on X86_IO_APIC
611 select MFD_INTEL_MSIC
613 Select to build a kernel capable of supporting Intel MID (Mobile
614 Internet Device) platform systems which do not have the PCI legacy
615 interfaces. If you are building for a PC class system say N here.
617 Intel MID platforms are based on an Intel processor and chipset which
618 consume less power than most of the x86 derivatives.
620 config X86_INTEL_QUARK
621 bool "Intel Quark platform support"
623 depends on X86_EXTENDED_PLATFORM
624 depends on X86_PLATFORM_DEVICES
628 depends on X86_IO_APIC
633 Select to include support for Quark X1000 SoC.
634 Say Y here if you have a Quark based system such as the Arduino
635 compatible Intel Galileo.
637 config X86_INTEL_LPSS
638 bool "Intel Low Power Subsystem Support"
639 depends on X86 && ACPI && PCI
644 Select to build support for Intel Low Power Subsystem such as
645 found on Intel Lynxpoint PCH. Selecting this option enables
646 things like clock tree (common clock framework) and pincontrol
647 which are needed by the LPSS peripheral drivers.
649 config X86_AMD_PLATFORM_DEVICE
650 bool "AMD ACPI2Platform devices support"
655 Select to interpret AMD specific ACPI device to platform device
656 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
657 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
658 implemented under PINCTRL subsystem.
661 tristate "Intel SoC IOSF Sideband support for SoC platforms"
664 This option enables sideband register access support for Intel SoC
665 platforms. On these platforms the IOSF sideband is used in lieu of
666 MSR's for some register accesses, mostly but not limited to thermal
667 and power. Drivers may query the availability of this device to
668 determine if they need the sideband in order to work on these
669 platforms. The sideband is available on the following SoC products.
670 This list is not meant to be exclusive.
675 You should say Y if you are running a kernel on one of these SoC's.
677 config IOSF_MBI_DEBUG
678 bool "Enable IOSF sideband access through debugfs"
679 depends on IOSF_MBI && DEBUG_FS
681 Select this option to expose the IOSF sideband access registers (MCR,
682 MDR, MCRX) through debugfs to write and read register information from
683 different units on the SoC. This is most useful for obtaining device
684 state information for debug and analysis. As this is a general access
685 mechanism, users of this option would have specific knowledge of the
686 device they want to access.
688 If you don't require the option or are in doubt, say N.
691 bool "RDC R-321x SoC"
693 depends on X86_EXTENDED_PLATFORM
695 select X86_REBOOTFIXUPS
697 This option is needed for RDC R-321x system-on-chip, also known
699 If you don't have one of these chips, you should say N here.
701 config X86_32_NON_STANDARD
702 bool "Support non-standard 32-bit SMP architectures"
703 depends on X86_32 && SMP
704 depends on X86_EXTENDED_PLATFORM
706 This option compiles in the bigsmp and STA2X11 default
707 subarchitectures. It is intended for a generic binary
708 kernel. If you select them all, kernel will probe it one by
709 one and will fallback to default.
711 # Alphabetically sorted list of Non standard 32 bit platforms
713 config X86_SUPPORTS_MEMORY_FAILURE
715 # MCE code calls memory_failure():
717 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
718 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
719 depends on X86_64 || !SPARSEMEM
720 select ARCH_SUPPORTS_MEMORY_FAILURE
723 bool "STA2X11 Companion Chip Support"
724 depends on X86_32_NON_STANDARD && PCI
729 This adds support for boards based on the STA2X11 IO-Hub,
730 a.k.a. "ConneXt". The chip is used in place of the standard
731 PC chipset, so all "standard" peripherals are missing. If this
732 option is selected the kernel will still be able to boot on
733 standard PC machines.
736 tristate "Eurobraille/Iris poweroff module"
739 The Iris machines from EuroBraille do not have APM or ACPI support
740 to shut themselves down properly. A special I/O sequence is
741 needed to do so, which is what this module does at
744 This is only for Iris machines from EuroBraille.
748 config SCHED_OMIT_FRAME_POINTER
750 prompt "Single-depth WCHAN output"
753 Calculate simpler /proc/<PID>/wchan values. If this option
754 is disabled then wchan values will recurse back to the
755 caller function. This provides more accurate wchan values,
756 at the expense of slightly more scheduling overhead.
758 If in doubt, say "Y".
760 menuconfig HYPERVISOR_GUEST
761 bool "Linux guest support"
763 Say Y here to enable options for running Linux under various hyper-
764 visors. This option enables basic hypervisor detection and platform
767 If you say N, all options in this submenu will be skipped and
768 disabled, and Linux guest support won't be built in.
773 bool "Enable paravirtualization code"
775 This changes the kernel so it can modify itself when it is run
776 under a hypervisor, potentially improving performance significantly
777 over full virtualization. However, when run without a hypervisor
778 the kernel is theoretically slower and slightly larger.
783 config PARAVIRT_DEBUG
784 bool "paravirt-ops debugging"
785 depends on PARAVIRT && DEBUG_KERNEL
787 Enable to debug paravirt_ops internals. Specifically, BUG if
788 a paravirt_op is missing when it is called.
790 config PARAVIRT_SPINLOCKS
791 bool "Paravirtualization layer for spinlocks"
792 depends on PARAVIRT && SMP
794 Paravirtualized spinlocks allow a pvops backend to replace the
795 spinlock implementation with something virtualization-friendly
796 (for example, block the virtual CPU rather than spinning).
798 It has a minimal impact on native kernels and gives a nice performance
799 benefit on paravirtualized KVM / Xen kernels.
801 If you are unsure how to answer this question, answer Y.
803 config X86_HV_CALLBACK_VECTOR
806 source "arch/x86/xen/Kconfig"
809 bool "KVM Guest support (including kvmclock)"
811 select PARAVIRT_CLOCK
812 select ARCH_CPUIDLE_HALTPOLL
813 select X86_HV_CALLBACK_VECTOR
816 This option enables various optimizations for running under the KVM
817 hypervisor. It includes a paravirtualized clock, so that instead
818 of relying on a PIT (or probably other) emulation by the
819 underlying device model, the host provides the guest with
820 timing infrastructure such as time of day, and system time
822 config ARCH_CPUIDLE_HALTPOLL
824 prompt "Disable host haltpoll when loading haltpoll driver"
826 If virtualized under KVM, disable host haltpoll.
829 bool "Support for running PVH guests"
831 This option enables the PVH entry point for guest virtual machines
832 as specified in the x86/HVM direct boot ABI.
834 config PARAVIRT_TIME_ACCOUNTING
835 bool "Paravirtual steal time accounting"
838 Select this option to enable fine granularity task steal time
839 accounting. Time spent executing other tasks in parallel with
840 the current vCPU is discounted from the vCPU power. To account for
841 that, there can be a small performance impact.
843 If in doubt, say N here.
845 config PARAVIRT_CLOCK
848 config JAILHOUSE_GUEST
849 bool "Jailhouse non-root cell support"
850 depends on X86_64 && PCI
853 This option allows to run Linux as guest in a Jailhouse non-root
854 cell. You can leave this option disabled if you only want to start
855 Jailhouse and run Linux afterwards in the root cell.
858 bool "ACRN Guest support"
860 select X86_HV_CALLBACK_VECTOR
862 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
863 a flexible, lightweight reference open-source hypervisor, built with
864 real-time and safety-criticality in mind. It is built for embedded
865 IOT with small footprint and real-time features. More details can be
866 found in https://projectacrn.org/.
868 endif #HYPERVISOR_GUEST
870 source "arch/x86/Kconfig.cpu"
874 prompt "HPET Timer Support" if X86_32
876 Use the IA-PC HPET (High Precision Event Timer) to manage
877 time in preference to the PIT and RTC, if a HPET is
879 HPET is the next generation timer replacing legacy 8254s.
880 The HPET provides a stable time base on SMP
881 systems, unlike the TSC, but it is more expensive to access,
882 as it is off-chip. The interface used is documented
883 in the HPET spec, revision 1.
885 You can safely choose Y here. However, HPET will only be
886 activated if the platform and the BIOS support this feature.
887 Otherwise the 8254 will be used for timing services.
889 Choose N to continue using the legacy 8254 timer.
891 config HPET_EMULATE_RTC
893 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
896 def_bool y if X86_INTEL_MID
897 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
899 depends on X86_INTEL_MID && SFI
901 APB timer is the replacement for 8254, HPET on X86 MID platforms.
902 The APBT provides a stable time base on SMP
903 systems, unlike the TSC, but it is more expensive to access,
904 as it is off-chip. APB timers are always running regardless of CPU
905 C states, they are used as per CPU clockevent device when possible.
907 # Mark as expert because too many people got it wrong.
908 # The code disables itself when not needed.
911 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
912 bool "Enable DMI scanning" if EXPERT
914 Enabled scanning of DMI to identify machine quirks. Say Y
915 here unless you have verified that your setup is not
916 affected by entries in the DMI blacklist. Required by PNP
920 bool "Old AMD GART IOMMU support"
924 depends on X86_64 && PCI && AMD_NB
926 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
927 GART based hardware IOMMUs.
929 The GART supports full DMA access for devices with 32-bit access
930 limitations, on systems with more than 3 GB. This is usually needed
931 for USB, sound, many IDE/SATA chipsets and some other devices.
933 Newer systems typically have a modern AMD IOMMU, supported via
934 the CONFIG_AMD_IOMMU=y config option.
936 In normal configurations this driver is only active when needed:
937 there's more than 3 GB of memory and the system contains a
938 32-bit limited device.
943 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
944 depends on X86_64 && SMP && DEBUG_KERNEL
945 select CPUMASK_OFFSTACK
947 Enable maximum number of CPUS and NUMA Nodes for this architecture.
951 # The maximum number of CPUs supported:
953 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
954 # and which can be configured interactively in the
955 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
957 # The ranges are different on 32-bit and 64-bit kernels, depending on
958 # hardware capabilities and scalability features of the kernel.
960 # ( If MAXSMP is enabled we just use the highest possible value and disable
961 # interactive configuration. )
964 config NR_CPUS_RANGE_BEGIN
966 default NR_CPUS_RANGE_END if MAXSMP
970 config NR_CPUS_RANGE_END
973 default 64 if SMP && X86_BIGSMP
974 default 8 if SMP && !X86_BIGSMP
977 config NR_CPUS_RANGE_END
980 default 8192 if SMP && CPUMASK_OFFSTACK
981 default 512 if SMP && !CPUMASK_OFFSTACK
984 config NR_CPUS_DEFAULT
987 default 32 if X86_BIGSMP
991 config NR_CPUS_DEFAULT
994 default 8192 if MAXSMP
999 int "Maximum number of CPUs" if SMP && !MAXSMP
1000 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1001 default NR_CPUS_DEFAULT
1003 This allows you to specify the maximum number of CPUs which this
1004 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1005 supported value is 8192, otherwise the maximum value is 512. The
1006 minimum value which makes sense is 2.
1008 This is purely to save memory: each supported CPU adds about 8KB
1009 to the kernel image.
1016 prompt "Multi-core scheduler support"
1019 Multi-core scheduler support improves the CPU scheduler's decision
1020 making when dealing with multi-core CPU chips at a cost of slightly
1021 increased overhead in some places. If unsure say N here.
1023 config SCHED_MC_PRIO
1024 bool "CPU core priorities scheduler support"
1025 depends on SCHED_MC && CPU_SUP_INTEL
1026 select X86_INTEL_PSTATE
1030 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1031 core ordering determined at manufacturing time, which allows
1032 certain cores to reach higher turbo frequencies (when running
1033 single threaded workloads) than others.
1035 Enabling this kernel feature teaches the scheduler about
1036 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1037 scheduler's CPU selection logic accordingly, so that higher
1038 overall system performance can be achieved.
1040 This feature will have no effect on CPUs without this feature.
1042 If unsure say Y here.
1046 depends on !SMP && X86_LOCAL_APIC
1049 bool "Local APIC support on uniprocessors" if !PCI_MSI
1051 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1053 A local APIC (Advanced Programmable Interrupt Controller) is an
1054 integrated interrupt controller in the CPU. If you have a single-CPU
1055 system which has a processor with a local APIC, you can say Y here to
1056 enable and use it. If you say Y here even though your machine doesn't
1057 have a local APIC, then the kernel will still run with no slowdown at
1058 all. The local APIC supports CPU-generated self-interrupts (timer,
1059 performance counters), and the NMI watchdog which detects hard
1062 config X86_UP_IOAPIC
1063 bool "IO-APIC support on uniprocessors"
1064 depends on X86_UP_APIC
1066 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1067 SMP-capable replacement for PC-style interrupt controllers. Most
1068 SMP systems and many recent uniprocessor systems have one.
1070 If you have a single-CPU system with an IO-APIC, you can say Y here
1071 to use it. If you say Y here even though your machine doesn't have
1072 an IO-APIC, then the kernel will still run with no slowdown at all.
1074 config X86_LOCAL_APIC
1076 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1077 select IRQ_DOMAIN_HIERARCHY
1078 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1082 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1084 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1085 bool "Reroute for broken boot IRQs"
1086 depends on X86_IO_APIC
1088 This option enables a workaround that fixes a source of
1089 spurious interrupts. This is recommended when threaded
1090 interrupt handling is used on systems where the generation of
1091 superfluous "boot interrupts" cannot be disabled.
1093 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1094 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1095 kernel does during interrupt handling). On chipsets where this
1096 boot IRQ generation cannot be disabled, this workaround keeps
1097 the original IRQ line masked so that only the equivalent "boot
1098 IRQ" is delivered to the CPUs. The workaround also tells the
1099 kernel to set up the IRQ handler on the boot IRQ line. In this
1100 way only one interrupt is delivered to the kernel. Otherwise
1101 the spurious second interrupt may cause the kernel to bring
1102 down (vital) interrupt lines.
1104 Only affects "broken" chipsets. Interrupt sharing may be
1105 increased on these systems.
1108 bool "Machine Check / overheating reporting"
1109 select GENERIC_ALLOCATOR
1112 Machine Check support allows the processor to notify the
1113 kernel if it detects a problem (e.g. overheating, data corruption).
1114 The action the kernel takes depends on the severity of the problem,
1115 ranging from warning messages to halting the machine.
1117 config X86_MCELOG_LEGACY
1118 bool "Support for deprecated /dev/mcelog character device"
1121 Enable support for /dev/mcelog which is needed by the old mcelog
1122 userspace logging daemon. Consider switching to the new generation
1125 config X86_MCE_INTEL
1127 prompt "Intel MCE features"
1128 depends on X86_MCE && X86_LOCAL_APIC
1130 Additional support for intel specific MCE features such as
1131 the thermal monitor.
1135 prompt "AMD MCE features"
1136 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1138 Additional support for AMD specific MCE features such as
1139 the DRAM Error Threshold.
1141 config X86_ANCIENT_MCE
1142 bool "Support for old Pentium 5 / WinChip machine checks"
1143 depends on X86_32 && X86_MCE
1145 Include support for machine check handling on old Pentium 5 or WinChip
1146 systems. These typically need to be enabled explicitly on the command
1149 config X86_MCE_THRESHOLD
1150 depends on X86_MCE_AMD || X86_MCE_INTEL
1153 config X86_MCE_INJECT
1154 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1155 tristate "Machine check injector support"
1157 Provide support for injecting machine checks for testing purposes.
1158 If you don't know what a machine check is and you don't do kernel
1159 QA it is safe to say n.
1161 config X86_THERMAL_VECTOR
1163 depends on X86_MCE_INTEL
1165 source "arch/x86/events/Kconfig"
1167 config X86_LEGACY_VM86
1168 bool "Legacy VM86 support"
1171 This option allows user programs to put the CPU into V8086
1172 mode, which is an 80286-era approximation of 16-bit real mode.
1174 Some very old versions of X and/or vbetool require this option
1175 for user mode setting. Similarly, DOSEMU will use it if
1176 available to accelerate real mode DOS programs. However, any
1177 recent version of DOSEMU, X, or vbetool should be fully
1178 functional even without kernel VM86 support, as they will all
1179 fall back to software emulation. Nevertheless, if you are using
1180 a 16-bit DOS program where 16-bit performance matters, vm86
1181 mode might be faster than emulation and you might want to
1184 Note that any app that works on a 64-bit kernel is unlikely to
1185 need this option, as 64-bit kernels don't, and can't, support
1186 V8086 mode. This option is also unrelated to 16-bit protected
1187 mode and is not needed to run most 16-bit programs under Wine.
1189 Enabling this option increases the complexity of the kernel
1190 and slows down exception handling a tiny bit.
1192 If unsure, say N here.
1196 default X86_LEGACY_VM86
1199 bool "Enable support for 16-bit segments" if EXPERT
1201 depends on MODIFY_LDT_SYSCALL
1203 This option is required by programs like Wine to run 16-bit
1204 protected mode legacy code on x86 processors. Disabling
1205 this option saves about 300 bytes on i386, or around 6K text
1206 plus 16K runtime memory on x86-64,
1210 depends on X86_16BIT && X86_32
1214 depends on X86_16BIT && X86_64
1216 config X86_VSYSCALL_EMULATION
1217 bool "Enable vsyscall emulation" if EXPERT
1221 This enables emulation of the legacy vsyscall page. Disabling
1222 it is roughly equivalent to booting with vsyscall=none, except
1223 that it will also disable the helpful warning if a program
1224 tries to use a vsyscall. With this option set to N, offending
1225 programs will just segfault, citing addresses of the form
1228 This option is required by many programs built before 2013, and
1229 care should be used even with newer programs if set to N.
1231 Disabling this option saves about 7K of kernel size and
1232 possibly 4K of additional runtime pagetable memory.
1234 config X86_IOPL_IOPERM
1235 bool "IOPERM and IOPL Emulation"
1238 This enables the ioperm() and iopl() syscalls which are necessary
1239 for legacy applications.
1241 Legacy IOPL support is an overbroad mechanism which allows user
1242 space aside of accessing all 65536 I/O ports also to disable
1243 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1244 capabilities and permission from potentially active security
1247 The emulation restricts the functionality of the syscall to
1248 only allowing the full range I/O port access, but prevents the
1249 ability to disable interrupts from user space which would be
1250 granted if the hardware IOPL mechanism would be used.
1253 tristate "Toshiba Laptop support"
1256 This adds a driver to safely access the System Management Mode of
1257 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1258 not work on models with a Phoenix BIOS. The System Management Mode
1259 is used to set the BIOS and power saving options on Toshiba portables.
1261 For information on utilities to make use of this driver see the
1262 Toshiba Linux utilities web site at:
1263 <http://www.buzzard.org.uk/toshiba/>.
1265 Say Y if you intend to run this kernel on a Toshiba portable.
1269 tristate "Dell i8k legacy laptop support"
1271 select SENSORS_DELL_SMM
1273 This option enables legacy /proc/i8k userspace interface in hwmon
1274 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1275 temperature and allows controlling fan speeds of Dell laptops via
1276 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1277 it reports also power and hotkey status. For fan speed control is
1278 needed userspace package i8kutils.
1280 Say Y if you intend to run this kernel on old Dell laptops or want to
1281 use userspace package i8kutils.
1284 config X86_REBOOTFIXUPS
1285 bool "Enable X86 board specific fixups for reboot"
1288 This enables chipset and/or board specific fixups to be done
1289 in order to get reboot to work correctly. This is only needed on
1290 some combinations of hardware and BIOS. The symptom, for which
1291 this config is intended, is when reboot ends with a stalled/hung
1294 Currently, the only fixup is for the Geode machines using
1295 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1297 Say Y if you want to enable the fixup. Currently, it's safe to
1298 enable this option even if you don't need it.
1302 bool "CPU microcode loading support"
1304 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1306 If you say Y here, you will be able to update the microcode on
1307 Intel and AMD processors. The Intel support is for the IA32 family,
1308 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1309 AMD support is for families 0x10 and later. You will obviously need
1310 the actual microcode binary data itself which is not shipped with
1313 The preferred method to load microcode from a detached initrd is described
1314 in Documentation/x86/microcode.rst. For that you need to enable
1315 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1316 initrd for microcode blobs.
1318 In addition, you can build the microcode into the kernel. For that you
1319 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1322 config MICROCODE_INTEL
1323 bool "Intel microcode loading support"
1324 depends on MICROCODE
1327 This options enables microcode patch loading support for Intel
1330 For the current Intel microcode data package go to
1331 <https://downloadcenter.intel.com> and search for
1332 'Linux Processor Microcode Data File'.
1334 config MICROCODE_AMD
1335 bool "AMD microcode loading support"
1336 depends on MICROCODE
1338 If you select this option, microcode patch loading support for AMD
1339 processors will be enabled.
1341 config MICROCODE_OLD_INTERFACE
1342 bool "Ancient loading interface (DEPRECATED)"
1344 depends on MICROCODE
1346 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1347 which was used by userspace tools like iucode_tool and microcode.ctl.
1348 It is inadequate because it runs too late to be able to properly
1349 load microcode on a machine and it needs special tools. Instead, you
1350 should've switched to the early loading method with the initrd or
1351 builtin microcode by now: Documentation/x86/microcode.rst
1354 tristate "/dev/cpu/*/msr - Model-specific register support"
1356 This device gives privileged processes access to the x86
1357 Model-Specific Registers (MSRs). It is a character device with
1358 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1359 MSR accesses are directed to a specific CPU on multi-processor
1363 tristate "/dev/cpu/*/cpuid - CPU information support"
1365 This device gives processes access to the x86 CPUID instruction to
1366 be executed on a specific processor. It is a character device
1367 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1371 prompt "High Memory Support"
1378 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1379 However, the address space of 32-bit x86 processors is only 4
1380 Gigabytes large. That means that, if you have a large amount of
1381 physical memory, not all of it can be "permanently mapped" by the
1382 kernel. The physical memory that's not permanently mapped is called
1385 If you are compiling a kernel which will never run on a machine with
1386 more than 1 Gigabyte total physical RAM, answer "off" here (default
1387 choice and suitable for most users). This will result in a "3GB/1GB"
1388 split: 3GB are mapped so that each process sees a 3GB virtual memory
1389 space and the remaining part of the 4GB virtual memory space is used
1390 by the kernel to permanently map as much physical memory as
1393 If the machine has between 1 and 4 Gigabytes physical RAM, then
1396 If more than 4 Gigabytes is used then answer "64GB" here. This
1397 selection turns Intel PAE (Physical Address Extension) mode on.
1398 PAE implements 3-level paging on IA32 processors. PAE is fully
1399 supported by Linux, PAE mode is implemented on all recent Intel
1400 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1401 then the kernel will not boot on CPUs that don't support PAE!
1403 The actual amount of total physical memory will either be
1404 auto detected or can be forced by using a kernel command line option
1405 such as "mem=256M". (Try "man bootparam" or see the documentation of
1406 your boot loader (lilo or loadlin) about how to pass options to the
1407 kernel at boot time.)
1409 If unsure, say "off".
1414 Select this if you have a 32-bit processor and between 1 and 4
1415 gigabytes of physical RAM.
1419 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1422 Select this if you have a 32-bit processor and more than 4
1423 gigabytes of physical RAM.
1428 prompt "Memory split" if EXPERT
1432 Select the desired split between kernel and user memory.
1434 If the address range available to the kernel is less than the
1435 physical memory installed, the remaining memory will be available
1436 as "high memory". Accessing high memory is a little more costly
1437 than low memory, as it needs to be mapped into the kernel first.
1438 Note that increasing the kernel address space limits the range
1439 available to user programs, making the address space there
1440 tighter. Selecting anything other than the default 3G/1G split
1441 will also likely make your kernel incompatible with binary-only
1444 If you are not absolutely sure what you are doing, leave this
1448 bool "3G/1G user/kernel split"
1449 config VMSPLIT_3G_OPT
1451 bool "3G/1G user/kernel split (for full 1G low memory)"
1453 bool "2G/2G user/kernel split"
1454 config VMSPLIT_2G_OPT
1456 bool "2G/2G user/kernel split (for full 2G low memory)"
1458 bool "1G/3G user/kernel split"
1463 default 0xB0000000 if VMSPLIT_3G_OPT
1464 default 0x80000000 if VMSPLIT_2G
1465 default 0x78000000 if VMSPLIT_2G_OPT
1466 default 0x40000000 if VMSPLIT_1G
1472 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1475 bool "PAE (Physical Address Extension) Support"
1476 depends on X86_32 && !HIGHMEM4G
1477 select PHYS_ADDR_T_64BIT
1480 PAE is required for NX support, and furthermore enables
1481 larger swapspace support for non-overcommit purposes. It
1482 has the cost of more pagetable lookup overhead, and also
1483 consumes more pagetable space per process.
1486 bool "Enable 5-level page tables support"
1488 select DYNAMIC_MEMORY_LAYOUT
1489 select SPARSEMEM_VMEMMAP
1492 5-level paging enables access to larger address space:
1493 upto 128 PiB of virtual address space and 4 PiB of
1494 physical address space.
1496 It will be supported by future Intel CPUs.
1498 A kernel with the option enabled can be booted on machines that
1499 support 4- or 5-level paging.
1501 See Documentation/x86/x86_64/5level-paging.rst for more
1506 config X86_DIRECT_GBPAGES
1510 Certain kernel features effectively disable kernel
1511 linear 1 GB mappings (even if the CPU otherwise
1512 supports them), so don't confuse the user by printing
1513 that we have them enabled.
1515 config X86_CPA_STATISTICS
1516 bool "Enable statistic for Change Page Attribute"
1519 Expose statistics about the Change Page Attribute mechanism, which
1520 helps to determine the effectiveness of preserving large and huge
1521 page mappings when mapping protections are changed.
1523 config AMD_MEM_ENCRYPT
1524 bool "AMD Secure Memory Encryption (SME) support"
1525 depends on X86_64 && CPU_SUP_AMD
1526 select DMA_COHERENT_POOL
1527 select DYNAMIC_PHYSICAL_MASK
1528 select ARCH_USE_MEMREMAP_PROT
1529 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1530 select INSTRUCTION_DECODER
1532 Say yes to enable support for the encryption of system memory.
1533 This requires an AMD processor that supports Secure Memory
1536 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1537 bool "Activate AMD Secure Memory Encryption (SME) by default"
1539 depends on AMD_MEM_ENCRYPT
1541 Say yes to have system memory encrypted by default if running on
1542 an AMD processor that supports Secure Memory Encryption (SME).
1544 If set to Y, then the encryption of system memory can be
1545 deactivated with the mem_encrypt=off command line option.
1547 If set to N, then the encryption of system memory can be
1548 activated with the mem_encrypt=on command line option.
1550 # Common NUMA Features
1552 bool "NUMA Memory Allocation and Scheduler Support"
1554 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1555 default y if X86_BIGSMP
1557 Enable NUMA (Non-Uniform Memory Access) support.
1559 The kernel will try to allocate memory used by a CPU on the
1560 local memory controller of the CPU and add some more
1561 NUMA awareness to the kernel.
1563 For 64-bit this is recommended if the system is Intel Core i7
1564 (or later), AMD Opteron, or EM64T NUMA.
1566 For 32-bit this is only needed if you boot a 32-bit
1567 kernel on a 64-bit NUMA platform.
1569 Otherwise, you should say N.
1573 prompt "Old style AMD Opteron NUMA detection"
1574 depends on X86_64 && NUMA && PCI
1576 Enable AMD NUMA node topology detection. You should say Y here if
1577 you have a multi processor AMD system. This uses an old method to
1578 read the NUMA configuration directly from the builtin Northbridge
1579 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1580 which also takes priority if both are compiled in.
1582 config X86_64_ACPI_NUMA
1584 prompt "ACPI NUMA detection"
1585 depends on X86_64 && NUMA && ACPI && PCI
1588 Enable ACPI SRAT based node topology detection.
1591 bool "NUMA emulation"
1594 Enable NUMA emulation. A flat machine will be split
1595 into virtual nodes when booted with "numa=fake=N", where N is the
1596 number of nodes. This is only useful for debugging.
1599 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1601 default "10" if MAXSMP
1602 default "6" if X86_64
1604 depends on NEED_MULTIPLE_NODES
1606 Specify the maximum number of NUMA Nodes available on the target
1607 system. Increases memory reserved to accommodate various tables.
1609 config ARCH_FLATMEM_ENABLE
1611 depends on X86_32 && !NUMA
1613 config ARCH_SPARSEMEM_ENABLE
1615 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1616 select SPARSEMEM_STATIC if X86_32
1617 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1619 config ARCH_SPARSEMEM_DEFAULT
1620 def_bool X86_64 || (NUMA && X86_32)
1622 config ARCH_SELECT_MEMORY_MODEL
1624 depends on ARCH_SPARSEMEM_ENABLE
1626 config ARCH_MEMORY_PROBE
1627 bool "Enable sysfs memory/probe interface"
1628 depends on X86_64 && MEMORY_HOTPLUG
1630 This option enables a sysfs memory/probe interface for testing.
1631 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1632 If you are unsure how to answer this question, answer N.
1634 config ARCH_PROC_KCORE_TEXT
1636 depends on X86_64 && PROC_KCORE
1638 config ILLEGAL_POINTER_VALUE
1641 default 0xdead000000000000 if X86_64
1643 config X86_PMEM_LEGACY_DEVICE
1646 config X86_PMEM_LEGACY
1647 tristate "Support non-standard NVDIMMs and ADR protected memory"
1648 depends on PHYS_ADDR_T_64BIT
1650 select X86_PMEM_LEGACY_DEVICE
1651 select NUMA_KEEP_MEMINFO if NUMA
1654 Treat memory marked using the non-standard e820 type of 12 as used
1655 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1656 The kernel will offer these regions to the 'pmem' driver so
1657 they can be used for persistent storage.
1662 bool "Allocate 3rd-level pagetables from highmem"
1665 The VM uses one page table entry for each page of physical memory.
1666 For systems with a lot of RAM, this can be wasteful of precious
1667 low memory. Setting this option will put user-space page table
1668 entries in high memory.
1670 config X86_CHECK_BIOS_CORRUPTION
1671 bool "Check for low memory corruption"
1673 Periodically check for memory corruption in low memory, which
1674 is suspected to be caused by BIOS. Even when enabled in the
1675 configuration, it is disabled at runtime. Enable it by
1676 setting "memory_corruption_check=1" on the kernel command
1677 line. By default it scans the low 64k of memory every 60
1678 seconds; see the memory_corruption_check_size and
1679 memory_corruption_check_period parameters in
1680 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1682 When enabled with the default parameters, this option has
1683 almost no overhead, as it reserves a relatively small amount
1684 of memory and scans it infrequently. It both detects corruption
1685 and prevents it from affecting the running system.
1687 It is, however, intended as a diagnostic tool; if repeatable
1688 BIOS-originated corruption always affects the same memory,
1689 you can use memmap= to prevent the kernel from using that
1692 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1693 bool "Set the default setting of memory_corruption_check"
1694 depends on X86_CHECK_BIOS_CORRUPTION
1697 Set whether the default state of memory_corruption_check is
1700 config X86_RESERVE_LOW
1701 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1705 Specify the amount of low memory to reserve for the BIOS.
1707 The first page contains BIOS data structures that the kernel
1708 must not use, so that page must always be reserved.
1710 By default we reserve the first 64K of physical RAM, as a
1711 number of BIOSes are known to corrupt that memory range
1712 during events such as suspend/resume or monitor cable
1713 insertion, so it must not be used by the kernel.
1715 You can set this to 4 if you are absolutely sure that you
1716 trust the BIOS to get all its memory reservations and usages
1717 right. If you know your BIOS have problems beyond the
1718 default 64K area, you can set this to 640 to avoid using the
1719 entire low memory range.
1721 If you have doubts about the BIOS (e.g. suspend/resume does
1722 not work or there's kernel crashes after certain hardware
1723 hotplug events) then you might want to enable
1724 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1725 typical corruption patterns.
1727 Leave this to the default value of 64 if you are unsure.
1729 config MATH_EMULATION
1731 depends on MODIFY_LDT_SYSCALL
1732 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1734 Linux can emulate a math coprocessor (used for floating point
1735 operations) if you don't have one. 486DX and Pentium processors have
1736 a math coprocessor built in, 486SX and 386 do not, unless you added
1737 a 487DX or 387, respectively. (The messages during boot time can
1738 give you some hints here ["man dmesg"].) Everyone needs either a
1739 coprocessor or this emulation.
1741 If you don't have a math coprocessor, you need to say Y here; if you
1742 say Y here even though you have a coprocessor, the coprocessor will
1743 be used nevertheless. (This behavior can be changed with the kernel
1744 command line option "no387", which comes handy if your coprocessor
1745 is broken. Try "man bootparam" or see the documentation of your boot
1746 loader (lilo or loadlin) about how to pass options to the kernel at
1747 boot time.) This means that it is a good idea to say Y here if you
1748 intend to use this kernel on different machines.
1750 More information about the internals of the Linux math coprocessor
1751 emulation can be found in <file:arch/x86/math-emu/README>.
1753 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1754 kernel, it won't hurt.
1758 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1760 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1761 the Memory Type Range Registers (MTRRs) may be used to control
1762 processor access to memory ranges. This is most useful if you have
1763 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1764 allows bus write transfers to be combined into a larger transfer
1765 before bursting over the PCI/AGP bus. This can increase performance
1766 of image write operations 2.5 times or more. Saying Y here creates a
1767 /proc/mtrr file which may be used to manipulate your processor's
1768 MTRRs. Typically the X server should use this.
1770 This code has a reasonably generic interface so that similar
1771 control registers on other processors can be easily supported
1774 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1775 Registers (ARRs) which provide a similar functionality to MTRRs. For
1776 these, the ARRs are used to emulate the MTRRs.
1777 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1778 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1779 write-combining. All of these processors are supported by this code
1780 and it makes sense to say Y here if you have one of them.
1782 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1783 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1784 can lead to all sorts of problems, so it's good to say Y here.
1786 You can safely say Y even if your machine doesn't have MTRRs, you'll
1787 just add about 9 KB to your kernel.
1789 See <file:Documentation/x86/mtrr.rst> for more information.
1791 config MTRR_SANITIZER
1793 prompt "MTRR cleanup support"
1796 Convert MTRR layout from continuous to discrete, so X drivers can
1797 add writeback entries.
1799 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1800 The largest mtrr entry size for a continuous block can be set with
1805 config MTRR_SANITIZER_ENABLE_DEFAULT
1806 int "MTRR cleanup enable value (0-1)"
1809 depends on MTRR_SANITIZER
1811 Enable mtrr cleanup default value
1813 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1814 int "MTRR cleanup spare reg num (0-7)"
1817 depends on MTRR_SANITIZER
1819 mtrr cleanup spare entries default, it can be changed via
1820 mtrr_spare_reg_nr=N on the kernel command line.
1824 prompt "x86 PAT support" if EXPERT
1827 Use PAT attributes to setup page level cache control.
1829 PATs are the modern equivalents of MTRRs and are much more
1830 flexible than MTRRs.
1832 Say N here if you see bootup problems (boot crash, boot hang,
1833 spontaneous reboots) or a non-working video driver.
1837 config ARCH_USES_PG_UNCACHED
1843 prompt "x86 architectural random number generator" if EXPERT
1845 Enable the x86 architectural RDRAND instruction
1846 (Intel Bull Mountain technology) to generate random numbers.
1847 If supported, this is a high bandwidth, cryptographically
1848 secure hardware random number generator.
1852 prompt "Supervisor Mode Access Prevention" if EXPERT
1854 Supervisor Mode Access Prevention (SMAP) is a security
1855 feature in newer Intel processors. There is a small
1856 performance cost if this enabled and turned on; there is
1857 also a small increase in the kernel size if this is enabled.
1863 prompt "User Mode Instruction Prevention" if EXPERT
1865 User Mode Instruction Prevention (UMIP) is a security feature in
1866 some x86 processors. If enabled, a general protection fault is
1867 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1868 executed in user mode. These instructions unnecessarily expose
1869 information about the hardware state.
1871 The vast majority of applications do not use these instructions.
1872 For the very few that do, software emulation is provided in
1873 specific cases in protected and virtual-8086 modes. Emulated
1876 config X86_INTEL_MEMORY_PROTECTION_KEYS
1877 prompt "Memory Protection Keys"
1879 # Note: only available in 64-bit mode
1880 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1881 select ARCH_USES_HIGH_VMA_FLAGS
1882 select ARCH_HAS_PKEYS
1884 Memory Protection Keys provides a mechanism for enforcing
1885 page-based protections, but without requiring modification of the
1886 page tables when an application changes protection domains.
1888 For details, see Documentation/core-api/protection-keys.rst
1893 prompt "TSX enable mode"
1894 depends on CPU_SUP_INTEL
1895 default X86_INTEL_TSX_MODE_OFF
1897 Intel's TSX (Transactional Synchronization Extensions) feature
1898 allows to optimize locking protocols through lock elision which
1899 can lead to a noticeable performance boost.
1901 On the other hand it has been shown that TSX can be exploited
1902 to form side channel attacks (e.g. TAA) and chances are there
1903 will be more of those attacks discovered in the future.
1905 Therefore TSX is not enabled by default (aka tsx=off). An admin
1906 might override this decision by tsx=on the command line parameter.
1907 Even with TSX enabled, the kernel will attempt to enable the best
1908 possible TAA mitigation setting depending on the microcode available
1909 for the particular machine.
1911 This option allows to set the default tsx mode between tsx=on, =off
1912 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1915 Say off if not sure, auto if TSX is in use but it should be used on safe
1916 platforms or on if TSX is in use and the security aspect of tsx is not
1919 config X86_INTEL_TSX_MODE_OFF
1922 TSX is disabled if possible - equals to tsx=off command line parameter.
1924 config X86_INTEL_TSX_MODE_ON
1927 TSX is always enabled on TSX capable HW - equals the tsx=on command
1930 config X86_INTEL_TSX_MODE_AUTO
1933 TSX is enabled on TSX capable HW that is believed to be safe against
1934 side channel attacks- equals the tsx=auto command line parameter.
1938 bool "Software Guard eXtensions (SGX)"
1939 depends on X86_64 && CPU_SUP_INTEL
1941 depends on CRYPTO_SHA256=y
1945 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1946 that can be used by applications to set aside private regions of code
1947 and data, referred to as enclaves. An enclave's private memory can
1948 only be accessed by code running within the enclave. Accesses from
1949 outside the enclave, including other enclaves, are disallowed by
1955 bool "EFI runtime service support"
1958 select EFI_RUNTIME_WRAPPERS
1960 This enables the kernel to use EFI runtime services that are
1961 available (such as the EFI variable services).
1963 This option is only useful on systems that have EFI firmware.
1964 In addition, you should use the latest ELILO loader available
1965 at <http://elilo.sourceforge.net> in order to take advantage
1966 of EFI runtime services. However, even with this option, the
1967 resultant kernel should continue to boot on existing non-EFI
1971 bool "EFI stub support"
1972 depends on EFI && !X86_USE_3DNOW
1973 depends on $(cc-option,-mabi=ms) || X86_32
1976 This kernel feature allows a bzImage to be loaded directly
1977 by EFI firmware without the use of a bootloader.
1979 See Documentation/admin-guide/efi-stub.rst for more information.
1982 bool "EFI mixed-mode support"
1983 depends on EFI_STUB && X86_64
1985 Enabling this feature allows a 64-bit kernel to be booted
1986 on a 32-bit firmware, provided that your CPU supports 64-bit
1989 Note that it is not possible to boot a mixed-mode enabled
1990 kernel via the EFI boot stub - a bootloader that supports
1991 the EFI handover protocol must be used.
1995 source "kernel/Kconfig.hz"
1998 bool "kexec system call"
2001 kexec is a system call that implements the ability to shutdown your
2002 current kernel, and to start another kernel. It is like a reboot
2003 but it is independent of the system firmware. And like a reboot
2004 you can start any kernel with it, not just Linux.
2006 The name comes from the similarity to the exec system call.
2008 It is an ongoing process to be certain the hardware in a machine
2009 is properly shutdown, so do not be surprised if this code does not
2010 initially work for you. As of this writing the exact hardware
2011 interface is strongly in flux, so no good recommendation can be
2015 bool "kexec file based system call"
2020 depends on CRYPTO_SHA256=y
2022 This is new version of kexec system call. This system call is
2023 file based and takes file descriptors as system call argument
2024 for kernel and initramfs as opposed to list of segments as
2025 accepted by previous system call.
2027 config ARCH_HAS_KEXEC_PURGATORY
2031 bool "Verify kernel signature during kexec_file_load() syscall"
2032 depends on KEXEC_FILE
2035 This option makes the kexec_file_load() syscall check for a valid
2036 signature of the kernel image. The image can still be loaded without
2037 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2038 there's a signature that we can check, then it must be valid.
2040 In addition to this option, you need to enable signature
2041 verification for the corresponding kernel image type being
2042 loaded in order for this to work.
2044 config KEXEC_SIG_FORCE
2045 bool "Require a valid signature in kexec_file_load() syscall"
2046 depends on KEXEC_SIG
2048 This option makes kernel signature verification mandatory for
2049 the kexec_file_load() syscall.
2051 config KEXEC_BZIMAGE_VERIFY_SIG
2052 bool "Enable bzImage signature verification support"
2053 depends on KEXEC_SIG
2054 depends on SIGNED_PE_FILE_VERIFICATION
2055 select SYSTEM_TRUSTED_KEYRING
2057 Enable bzImage signature verification support.
2060 bool "kernel crash dumps"
2061 depends on X86_64 || (X86_32 && HIGHMEM)
2063 Generate crash dump after being started by kexec.
2064 This should be normally only set in special crash dump kernels
2065 which are loaded in the main kernel with kexec-tools into
2066 a specially reserved region and then later executed after
2067 a crash by kdump/kexec. The crash dump kernel must be compiled
2068 to a memory address not used by the main kernel or BIOS using
2069 PHYSICAL_START, or it must be built as a relocatable image
2070 (CONFIG_RELOCATABLE=y).
2071 For more details see Documentation/admin-guide/kdump/kdump.rst
2075 depends on KEXEC && HIBERNATION
2077 Jump between original kernel and kexeced kernel and invoke
2078 code in physical address mode via KEXEC
2080 config PHYSICAL_START
2081 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2084 This gives the physical address where the kernel is loaded.
2086 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2087 bzImage will decompress itself to above physical address and
2088 run from there. Otherwise, bzImage will run from the address where
2089 it has been loaded by the boot loader and will ignore above physical
2092 In normal kdump cases one does not have to set/change this option
2093 as now bzImage can be compiled as a completely relocatable image
2094 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2095 address. This option is mainly useful for the folks who don't want
2096 to use a bzImage for capturing the crash dump and want to use a
2097 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2098 to be specifically compiled to run from a specific memory area
2099 (normally a reserved region) and this option comes handy.
2101 So if you are using bzImage for capturing the crash dump,
2102 leave the value here unchanged to 0x1000000 and set
2103 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2104 for capturing the crash dump change this value to start of
2105 the reserved region. In other words, it can be set based on
2106 the "X" value as specified in the "crashkernel=YM@XM"
2107 command line boot parameter passed to the panic-ed
2108 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2109 for more details about crash dumps.
2111 Usage of bzImage for capturing the crash dump is recommended as
2112 one does not have to build two kernels. Same kernel can be used
2113 as production kernel and capture kernel. Above option should have
2114 gone away after relocatable bzImage support is introduced. But it
2115 is present because there are users out there who continue to use
2116 vmlinux for dump capture. This option should go away down the
2119 Don't change this unless you know what you are doing.
2122 bool "Build a relocatable kernel"
2125 This builds a kernel image that retains relocation information
2126 so it can be loaded someplace besides the default 1MB.
2127 The relocations tend to make the kernel binary about 10% larger,
2128 but are discarded at runtime.
2130 One use is for the kexec on panic case where the recovery kernel
2131 must live at a different physical address than the primary
2134 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2135 it has been loaded at and the compile time physical address
2136 (CONFIG_PHYSICAL_START) is used as the minimum location.
2138 config RANDOMIZE_BASE
2139 bool "Randomize the address of the kernel image (KASLR)"
2140 depends on RELOCATABLE
2143 In support of Kernel Address Space Layout Randomization (KASLR),
2144 this randomizes the physical address at which the kernel image
2145 is decompressed and the virtual address where the kernel
2146 image is mapped, as a security feature that deters exploit
2147 attempts relying on knowledge of the location of kernel
2150 On 64-bit, the kernel physical and virtual addresses are
2151 randomized separately. The physical address will be anywhere
2152 between 16MB and the top of physical memory (up to 64TB). The
2153 virtual address will be randomized from 16MB up to 1GB (9 bits
2154 of entropy). Note that this also reduces the memory space
2155 available to kernel modules from 1.5GB to 1GB.
2157 On 32-bit, the kernel physical and virtual addresses are
2158 randomized together. They will be randomized from 16MB up to
2159 512MB (8 bits of entropy).
2161 Entropy is generated using the RDRAND instruction if it is
2162 supported. If RDTSC is supported, its value is mixed into
2163 the entropy pool as well. If neither RDRAND nor RDTSC are
2164 supported, then entropy is read from the i8254 timer. The
2165 usable entropy is limited by the kernel being built using
2166 2GB addressing, and that PHYSICAL_ALIGN must be at a
2167 minimum of 2MB. As a result, only 10 bits of entropy are
2168 theoretically possible, but the implementations are further
2169 limited due to memory layouts.
2173 # Relocation on x86 needs some additional build support
2174 config X86_NEED_RELOCS
2176 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2178 config PHYSICAL_ALIGN
2179 hex "Alignment value to which kernel should be aligned"
2181 range 0x2000 0x1000000 if X86_32
2182 range 0x200000 0x1000000 if X86_64
2184 This value puts the alignment restrictions on physical address
2185 where kernel is loaded and run from. Kernel is compiled for an
2186 address which meets above alignment restriction.
2188 If bootloader loads the kernel at a non-aligned address and
2189 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2190 address aligned to above value and run from there.
2192 If bootloader loads the kernel at a non-aligned address and
2193 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2194 load address and decompress itself to the address it has been
2195 compiled for and run from there. The address for which kernel is
2196 compiled already meets above alignment restrictions. Hence the
2197 end result is that kernel runs from a physical address meeting
2198 above alignment restrictions.
2200 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2201 this value must be a multiple of 0x200000.
2203 Don't change this unless you know what you are doing.
2205 config DYNAMIC_MEMORY_LAYOUT
2208 This option makes base addresses of vmalloc and vmemmap as well as
2209 __PAGE_OFFSET movable during boot.
2211 config RANDOMIZE_MEMORY
2212 bool "Randomize the kernel memory sections"
2214 depends on RANDOMIZE_BASE
2215 select DYNAMIC_MEMORY_LAYOUT
2216 default RANDOMIZE_BASE
2218 Randomizes the base virtual address of kernel memory sections
2219 (physical memory mapping, vmalloc & vmemmap). This security feature
2220 makes exploits relying on predictable memory locations less reliable.
2222 The order of allocations remains unchanged. Entropy is generated in
2223 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2224 configuration have in average 30,000 different possible virtual
2225 addresses for each memory section.
2229 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2230 hex "Physical memory mapping padding" if EXPERT
2231 depends on RANDOMIZE_MEMORY
2232 default "0xa" if MEMORY_HOTPLUG
2234 range 0x1 0x40 if MEMORY_HOTPLUG
2237 Define the padding in terabytes added to the existing physical
2238 memory size during kernel memory randomization. It is useful
2239 for memory hotplug support but reduces the entropy available for
2240 address randomization.
2242 If unsure, leave at the default value.
2248 config BOOTPARAM_HOTPLUG_CPU0
2249 bool "Set default setting of cpu0_hotpluggable"
2250 depends on HOTPLUG_CPU
2252 Set whether default state of cpu0_hotpluggable is on or off.
2254 Say Y here to enable CPU0 hotplug by default. If this switch
2255 is turned on, there is no need to give cpu0_hotplug kernel
2256 parameter and the CPU0 hotplug feature is enabled by default.
2258 Please note: there are two known CPU0 dependencies if you want
2259 to enable the CPU0 hotplug feature either by this switch or by
2260 cpu0_hotplug kernel parameter.
2262 First, resume from hibernate or suspend always starts from CPU0.
2263 So hibernate and suspend are prevented if CPU0 is offline.
2265 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2266 offline if any interrupt can not migrate out of CPU0. There may
2267 be other CPU0 dependencies.
2269 Please make sure the dependencies are under your control before
2270 you enable this feature.
2272 Say N if you don't want to enable CPU0 hotplug feature by default.
2273 You still can enable the CPU0 hotplug feature at boot by kernel
2274 parameter cpu0_hotplug.
2276 config DEBUG_HOTPLUG_CPU0
2278 prompt "Debug CPU0 hotplug"
2279 depends on HOTPLUG_CPU
2281 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2282 soon as possible and boots up userspace with CPU0 offlined. User
2283 can online CPU0 back after boot time.
2285 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2286 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2287 compilation or giving cpu0_hotplug kernel parameter at boot.
2293 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2294 depends on COMPAT_32
2296 Certain buggy versions of glibc will crash if they are
2297 presented with a 32-bit vDSO that is not mapped at the address
2298 indicated in its segment table.
2300 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2301 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2302 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2303 the only released version with the bug, but OpenSUSE 9
2304 contains a buggy "glibc 2.3.2".
2306 The symptom of the bug is that everything crashes on startup, saying:
2307 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2309 Saying Y here changes the default value of the vdso32 boot
2310 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2311 This works around the glibc bug but hurts performance.
2313 If unsure, say N: if you are compiling your own kernel, you
2314 are unlikely to be using a buggy version of glibc.
2317 prompt "vsyscall table for legacy applications"
2319 default LEGACY_VSYSCALL_XONLY
2321 Legacy user code that does not know how to find the vDSO expects
2322 to be able to issue three syscalls by calling fixed addresses in
2323 kernel space. Since this location is not randomized with ASLR,
2324 it can be used to assist security vulnerability exploitation.
2326 This setting can be changed at boot time via the kernel command
2327 line parameter vsyscall=[emulate|xonly|none].
2329 On a system with recent enough glibc (2.14 or newer) and no
2330 static binaries, you can say None without a performance penalty
2331 to improve security.
2333 If unsure, select "Emulate execution only".
2335 config LEGACY_VSYSCALL_EMULATE
2336 bool "Full emulation"
2338 The kernel traps and emulates calls into the fixed vsyscall
2339 address mapping. This makes the mapping non-executable, but
2340 it still contains readable known contents, which could be
2341 used in certain rare security vulnerability exploits. This
2342 configuration is recommended when using legacy userspace
2343 that still uses vsyscalls along with legacy binary
2344 instrumentation tools that require code to be readable.
2346 An example of this type of legacy userspace is running
2347 Pin on an old binary that still uses vsyscalls.
2349 config LEGACY_VSYSCALL_XONLY
2350 bool "Emulate execution only"
2352 The kernel traps and emulates calls into the fixed vsyscall
2353 address mapping and does not allow reads. This
2354 configuration is recommended when userspace might use the
2355 legacy vsyscall area but support for legacy binary
2356 instrumentation of legacy code is not needed. It mitigates
2357 certain uses of the vsyscall area as an ASLR-bypassing
2360 config LEGACY_VSYSCALL_NONE
2363 There will be no vsyscall mapping at all. This will
2364 eliminate any risk of ASLR bypass due to the vsyscall
2365 fixed address mapping. Attempts to use the vsyscalls
2366 will be reported to dmesg, so that either old or
2367 malicious userspace programs can be identified.
2372 bool "Built-in kernel command line"
2374 Allow for specifying boot arguments to the kernel at
2375 build time. On some systems (e.g. embedded ones), it is
2376 necessary or convenient to provide some or all of the
2377 kernel boot arguments with the kernel itself (that is,
2378 to not rely on the boot loader to provide them.)
2380 To compile command line arguments into the kernel,
2381 set this option to 'Y', then fill in the
2382 boot arguments in CONFIG_CMDLINE.
2384 Systems with fully functional boot loaders (i.e. non-embedded)
2385 should leave this option set to 'N'.
2388 string "Built-in kernel command string"
2389 depends on CMDLINE_BOOL
2392 Enter arguments here that should be compiled into the kernel
2393 image and used at boot time. If the boot loader provides a
2394 command line at boot time, it is appended to this string to
2395 form the full kernel command line, when the system boots.
2397 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2398 change this behavior.
2400 In most cases, the command line (whether built-in or provided
2401 by the boot loader) should specify the device for the root
2404 config CMDLINE_OVERRIDE
2405 bool "Built-in command line overrides boot loader arguments"
2406 depends on CMDLINE_BOOL && CMDLINE != ""
2408 Set this option to 'Y' to have the kernel ignore the boot loader
2409 command line, and use ONLY the built-in command line.
2411 This is used to work around broken boot loaders. This should
2412 be set to 'N' under normal conditions.
2414 config MODIFY_LDT_SYSCALL
2415 bool "Enable the LDT (local descriptor table)" if EXPERT
2418 Linux can allow user programs to install a per-process x86
2419 Local Descriptor Table (LDT) using the modify_ldt(2) system
2420 call. This is required to run 16-bit or segmented code such as
2421 DOSEMU or some Wine programs. It is also used by some very old
2422 threading libraries.
2424 Enabling this feature adds a small amount of overhead to
2425 context switches and increases the low-level kernel attack
2426 surface. Disabling it removes the modify_ldt(2) system call.
2428 Saying 'N' here may make sense for embedded or server kernels.
2430 source "kernel/livepatch/Kconfig"
2434 config ARCH_HAS_ADD_PAGES
2436 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2438 config ARCH_ENABLE_MEMORY_HOTPLUG
2440 depends on X86_64 || (X86_32 && HIGHMEM)
2442 config ARCH_ENABLE_MEMORY_HOTREMOVE
2444 depends on MEMORY_HOTPLUG
2446 config USE_PERCPU_NUMA_NODE_ID
2450 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2452 depends on X86_64 || X86_PAE
2454 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2456 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2458 config ARCH_ENABLE_THP_MIGRATION
2460 depends on X86_64 && TRANSPARENT_HUGEPAGE
2462 menu "Power management and ACPI options"
2464 config ARCH_HIBERNATION_HEADER
2466 depends on HIBERNATION
2468 source "kernel/power/Kconfig"
2470 source "drivers/acpi/Kconfig"
2472 source "drivers/sfi/Kconfig"
2479 tristate "APM (Advanced Power Management) BIOS support"
2480 depends on X86_32 && PM_SLEEP
2482 APM is a BIOS specification for saving power using several different
2483 techniques. This is mostly useful for battery powered laptops with
2484 APM compliant BIOSes. If you say Y here, the system time will be
2485 reset after a RESUME operation, the /proc/apm device will provide
2486 battery status information, and user-space programs will receive
2487 notification of APM "events" (e.g. battery status change).
2489 If you select "Y" here, you can disable actual use of the APM
2490 BIOS by passing the "apm=off" option to the kernel at boot time.
2492 Note that the APM support is almost completely disabled for
2493 machines with more than one CPU.
2495 In order to use APM, you will need supporting software. For location
2496 and more information, read <file:Documentation/power/apm-acpi.rst>
2497 and the Battery Powered Linux mini-HOWTO, available from
2498 <http://www.tldp.org/docs.html#howto>.
2500 This driver does not spin down disk drives (see the hdparm(8)
2501 manpage ("man 8 hdparm") for that), and it doesn't turn off
2502 VESA-compliant "green" monitors.
2504 This driver does not support the TI 4000M TravelMate and the ACER
2505 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2506 desktop machines also don't have compliant BIOSes, and this driver
2507 may cause those machines to panic during the boot phase.
2509 Generally, if you don't have a battery in your machine, there isn't
2510 much point in using this driver and you should say N. If you get
2511 random kernel OOPSes or reboots that don't seem to be related to
2512 anything, try disabling/enabling this option (or disabling/enabling
2515 Some other things you should try when experiencing seemingly random,
2518 1) make sure that you have enough swap space and that it is
2520 2) pass the "no-hlt" option to the kernel
2521 3) switch on floating point emulation in the kernel and pass
2522 the "no387" option to the kernel
2523 4) pass the "floppy=nodma" option to the kernel
2524 5) pass the "mem=4M" option to the kernel (thereby disabling
2525 all but the first 4 MB of RAM)
2526 6) make sure that the CPU is not over clocked.
2527 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2528 8) disable the cache from your BIOS settings
2529 9) install a fan for the video card or exchange video RAM
2530 10) install a better fan for the CPU
2531 11) exchange RAM chips
2532 12) exchange the motherboard.
2534 To compile this driver as a module, choose M here: the
2535 module will be called apm.
2539 config APM_IGNORE_USER_SUSPEND
2540 bool "Ignore USER SUSPEND"
2542 This option will ignore USER SUSPEND requests. On machines with a
2543 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2544 series notebooks, it is necessary to say Y because of a BIOS bug.
2546 config APM_DO_ENABLE
2547 bool "Enable PM at boot time"
2549 Enable APM features at boot time. From page 36 of the APM BIOS
2550 specification: "When disabled, the APM BIOS does not automatically
2551 power manage devices, enter the Standby State, enter the Suspend
2552 State, or take power saving steps in response to CPU Idle calls."
2553 This driver will make CPU Idle calls when Linux is idle (unless this
2554 feature is turned off -- see "Do CPU IDLE calls", below). This
2555 should always save battery power, but more complicated APM features
2556 will be dependent on your BIOS implementation. You may need to turn
2557 this option off if your computer hangs at boot time when using APM
2558 support, or if it beeps continuously instead of suspending. Turn
2559 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2560 T400CDT. This is off by default since most machines do fine without
2565 bool "Make CPU Idle calls when idle"
2567 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2568 On some machines, this can activate improved power savings, such as
2569 a slowed CPU clock rate, when the machine is idle. These idle calls
2570 are made after the idle loop has run for some length of time (e.g.,
2571 333 mS). On some machines, this will cause a hang at boot time or
2572 whenever the CPU becomes idle. (On machines with more than one CPU,
2573 this option does nothing.)
2575 config APM_DISPLAY_BLANK
2576 bool "Enable console blanking using APM"
2578 Enable console blanking using the APM. Some laptops can use this to
2579 turn off the LCD backlight when the screen blanker of the Linux
2580 virtual console blanks the screen. Note that this is only used by
2581 the virtual console screen blanker, and won't turn off the backlight
2582 when using the X Window system. This also doesn't have anything to
2583 do with your VESA-compliant power-saving monitor. Further, this
2584 option doesn't work for all laptops -- it might not turn off your
2585 backlight at all, or it might print a lot of errors to the console,
2586 especially if you are using gpm.
2588 config APM_ALLOW_INTS
2589 bool "Allow interrupts during APM BIOS calls"
2591 Normally we disable external interrupts while we are making calls to
2592 the APM BIOS as a measure to lessen the effects of a badly behaving
2593 BIOS implementation. The BIOS should reenable interrupts if it
2594 needs to. Unfortunately, some BIOSes do not -- especially those in
2595 many of the newer IBM Thinkpads. If you experience hangs when you
2596 suspend, try setting this to Y. Otherwise, say N.
2600 source "drivers/cpufreq/Kconfig"
2602 source "drivers/cpuidle/Kconfig"
2604 source "drivers/idle/Kconfig"
2609 menu "Bus options (PCI etc.)"
2612 prompt "PCI access mode"
2613 depends on X86_32 && PCI
2616 On PCI systems, the BIOS can be used to detect the PCI devices and
2617 determine their configuration. However, some old PCI motherboards
2618 have BIOS bugs and may crash if this is done. Also, some embedded
2619 PCI-based systems don't have any BIOS at all. Linux can also try to
2620 detect the PCI hardware directly without using the BIOS.
2622 With this option, you can specify how Linux should detect the
2623 PCI devices. If you choose "BIOS", the BIOS will be used,
2624 if you choose "Direct", the BIOS won't be used, and if you
2625 choose "MMConfig", then PCI Express MMCONFIG will be used.
2626 If you choose "Any", the kernel will try MMCONFIG, then the
2627 direct access method and falls back to the BIOS if that doesn't
2628 work. If unsure, go with the default, which is "Any".
2633 config PCI_GOMMCONFIG
2650 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2652 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2655 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2658 bool "Support mmconfig PCI config space access" if X86_64
2660 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2661 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2665 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2669 depends on PCI && XEN
2672 config MMCONF_FAM10H
2674 depends on X86_64 && PCI_MMCONFIG && ACPI
2676 config PCI_CNB20LE_QUIRK
2677 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2680 Read the PCI windows out of the CNB20LE host bridge. This allows
2681 PCI hotplug to work on systems with the CNB20LE chipset which do
2684 There's no public spec for this chipset, and this functionality
2685 is known to be incomplete.
2687 You should say N unless you know you need this.
2690 bool "ISA bus support on modern systems" if EXPERT
2692 Expose ISA bus device drivers and options available for selection and
2693 configuration. Enable this option if your target machine has an ISA
2694 bus. ISA is an older system, displaced by PCI and newer bus
2695 architectures -- if your target machine is modern, it probably does
2696 not have an ISA bus.
2700 # x86_64 have no ISA slots, but can have ISA-style DMA.
2702 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2705 Enables ISA-style DMA support for devices requiring such controllers.
2713 Find out whether you have ISA slots on your motherboard. ISA is the
2714 name of a bus system, i.e. the way the CPU talks to the other stuff
2715 inside your box. Other bus systems are PCI, EISA, MicroChannel
2716 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2717 newer boards don't support it. If you have ISA, say Y, otherwise N.
2720 tristate "NatSemi SCx200 support"
2722 This provides basic support for National Semiconductor's
2723 (now AMD's) Geode processors. The driver probes for the
2724 PCI-IDs of several on-chip devices, so its a good dependency
2725 for other scx200_* drivers.
2727 If compiled as a module, the driver is named scx200.
2729 config SCx200HR_TIMER
2730 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2734 This driver provides a clocksource built upon the on-chip
2735 27MHz high-resolution timer. Its also a workaround for
2736 NSC Geode SC-1100's buggy TSC, which loses time when the
2737 processor goes idle (as is done by the scheduler). The
2738 other workaround is idle=poll boot option.
2741 bool "One Laptop Per Child support"
2749 Add support for detecting the unique features of the OLPC
2753 bool "OLPC XO-1 Power Management"
2754 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2756 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2759 bool "OLPC XO-1 Real Time Clock"
2760 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2762 Add support for the XO-1 real time clock, which can be used as a
2763 programmable wakeup source.
2766 bool "OLPC XO-1 SCI extras"
2767 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2771 Add support for SCI-based features of the OLPC XO-1 laptop:
2772 - EC-driven system wakeups
2776 - AC adapter status updates
2777 - Battery status updates
2779 config OLPC_XO15_SCI
2780 bool "OLPC XO-1.5 SCI extras"
2781 depends on OLPC && ACPI
2784 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2785 - EC-driven system wakeups
2786 - AC adapter status updates
2787 - Battery status updates
2790 bool "PCEngines ALIX System Support (LED setup)"
2793 This option enables system support for the PCEngines ALIX.
2794 At present this just sets up LEDs for GPIO control on
2795 ALIX2/3/6 boards. However, other system specific setup should
2798 Note: You must still enable the drivers for GPIO and LED support
2799 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2801 Note: You have to set alix.force=1 for boards with Award BIOS.
2804 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2807 This option enables system support for the Soekris Engineering net5501.
2810 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2814 This option enables system support for the Traverse Technologies GEOS.
2817 bool "Technologic Systems TS-5500 platform support"
2819 select CHECK_SIGNATURE
2823 This option enables system support for the Technologic Systems TS-5500.
2829 depends on CPU_SUP_AMD && PCI
2832 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2834 Firmwares often provide initial graphics framebuffers so the BIOS,
2835 bootloader or kernel can show basic video-output during boot for
2836 user-guidance and debugging. Historically, x86 used the VESA BIOS
2837 Extensions and EFI-framebuffers for this, which are mostly limited
2839 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2840 framebuffers so the new generic system-framebuffer drivers can be
2841 used on x86. If the framebuffer is not compatible with the generic
2842 modes, it is advertised as fallback platform framebuffer so legacy
2843 drivers like efifb, vesafb and uvesafb can pick it up.
2844 If this option is not selected, all system framebuffers are always
2845 marked as fallback platform framebuffers as usual.
2847 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2848 not be able to pick up generic system framebuffers if this option
2849 is selected. You are highly encouraged to enable simplefb as
2850 replacement if you select this option. simplefb can correctly deal
2851 with generic system framebuffers. But you should still keep vesafb
2852 and others enabled as fallback if a system framebuffer is
2853 incompatible with simplefb.
2860 menu "Binary Emulations"
2862 config IA32_EMULATION
2863 bool "IA32 Emulation"
2865 select ARCH_WANT_OLD_COMPAT_IPC
2867 select COMPAT_BINFMT_ELF
2868 select COMPAT_OLD_SIGACTION
2870 Include code to run legacy 32-bit programs under a
2871 64-bit kernel. You should likely turn this on, unless you're
2872 100% sure that you don't have any 32-bit programs left.
2875 tristate "IA32 a.out support"
2876 depends on IA32_EMULATION
2879 Support old a.out binaries in the 32bit emulation.
2882 bool "x32 ABI for 64-bit mode"
2885 Include code to run binaries for the x32 native 32-bit ABI
2886 for 64-bit processors. An x32 process gets access to the
2887 full 64-bit register file and wide data path while leaving
2888 pointers at 32 bits for smaller memory footprint.
2890 You will need a recent binutils (2.22 or later) with
2891 elf32_x86_64 support enabled to compile a kernel with this
2896 depends on IA32_EMULATION || X86_32
2898 select OLD_SIGSUSPEND3
2902 depends on IA32_EMULATION || X86_X32
2905 config COMPAT_FOR_U64_ALIGNMENT
2908 config SYSVIPC_COMPAT
2916 config HAVE_ATOMIC_IOMAP
2920 source "drivers/firmware/Kconfig"
2922 source "arch/x86/kvm/Kconfig"
2924 source "arch/x86/Kconfig.assembler"