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
35 select ARCH_HAS_ELFCORE_COMPAT
38 config FORCE_DYNAMIC_FTRACE
41 depends on FUNCTION_TRACER
44 We keep the static function tracing (!DYNAMIC_FTRACE) around
45 in order to test the non static function tracing in the
46 generic code, as other architectures still use it. But we
47 only need to keep it around for x86_64. No need to keep it
48 for x86_32. For x86_32, force DYNAMIC_FTRACE.
52 # ( Note that options that are marked 'if X86_64' could in principle be
53 # ported to 32-bit as well. )
58 # Note: keep this list sorted alphabetically
60 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
61 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
62 select ARCH_32BIT_OFF_T if X86_32
63 select ARCH_CLOCKSOURCE_INIT
64 select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
65 select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
66 select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
67 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
68 select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
69 select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
70 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
71 select ARCH_HAS_CACHE_LINE_SIZE
72 select ARCH_HAS_DEBUG_VIRTUAL
73 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
74 select ARCH_HAS_DEVMEM_IS_ALLOWED
75 select ARCH_HAS_EARLY_DEBUG if KGDB
76 select ARCH_HAS_ELF_RANDOMIZE
77 select ARCH_HAS_FAST_MULTIPLIER
78 select ARCH_HAS_FILTER_PGPROT
79 select ARCH_HAS_FORTIFY_SOURCE
80 select ARCH_HAS_GCOV_PROFILE_ALL
81 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
82 select ARCH_HAS_MEM_ENCRYPT
83 select ARCH_HAS_MEMBARRIER_SYNC_CORE
84 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
85 select ARCH_HAS_PMEM_API if X86_64
86 select ARCH_HAS_PTE_DEVMAP if X86_64
87 select ARCH_HAS_PTE_SPECIAL
88 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
89 select ARCH_HAS_COPY_MC if X86_64
90 select ARCH_HAS_SET_MEMORY
91 select ARCH_HAS_SET_DIRECT_MAP
92 select ARCH_HAS_STRICT_KERNEL_RWX
93 select ARCH_HAS_STRICT_MODULE_RWX
94 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
95 select ARCH_HAS_SYSCALL_WRAPPER
96 select ARCH_HAS_UBSAN_SANITIZE_ALL
97 select ARCH_HAS_DEBUG_WX
98 select ARCH_HAS_ZONE_DMA_SET if EXPERT
99 select ARCH_HAVE_NMI_SAFE_CMPXCHG
100 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
101 select ARCH_MIGHT_HAVE_PC_PARPORT
102 select ARCH_MIGHT_HAVE_PC_SERIO
103 select ARCH_STACKWALK
104 select ARCH_SUPPORTS_ACPI
105 select ARCH_SUPPORTS_ATOMIC_RMW
106 select ARCH_SUPPORTS_DEBUG_PAGEALLOC
107 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
108 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096
109 select ARCH_SUPPORTS_LTO_CLANG
110 select ARCH_SUPPORTS_LTO_CLANG_THIN
111 select ARCH_USE_BUILTIN_BSWAP
112 select ARCH_USE_MEMTEST
113 select ARCH_USE_QUEUED_RWLOCKS
114 select ARCH_USE_QUEUED_SPINLOCKS
115 select ARCH_USE_SYM_ANNOTATIONS
116 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
117 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
118 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
119 select ARCH_WANTS_NO_INSTR
120 select ARCH_WANT_HUGE_PMD_SHARE
121 select ARCH_WANT_LD_ORPHAN_WARN
122 select ARCH_WANTS_THP_SWAP if X86_64
123 select ARCH_HAS_PARANOID_L1D_FLUSH
124 select BUILDTIME_TABLE_SORT
126 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
127 select CLOCKSOURCE_WATCHDOG
128 select DCACHE_WORD_ACCESS
129 select DYNAMIC_SIGFRAME
130 select EDAC_ATOMIC_SCRUB
132 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
133 select GENERIC_CLOCKEVENTS_MIN_ADJUST
134 select GENERIC_CMOS_UPDATE
135 select GENERIC_CPU_AUTOPROBE
136 select GENERIC_CPU_VULNERABILITIES
137 select GENERIC_EARLY_IOREMAP
139 select GENERIC_FIND_FIRST_BIT
141 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
142 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
143 select GENERIC_IRQ_MIGRATION if SMP
144 select GENERIC_IRQ_PROBE
145 select GENERIC_IRQ_RESERVATION_MODE
146 select GENERIC_IRQ_SHOW
147 select GENERIC_PENDING_IRQ if SMP
148 select GENERIC_PTDUMP
149 select GENERIC_SMP_IDLE_THREAD
150 select GENERIC_TIME_VSYSCALL
151 select GENERIC_GETTIMEOFDAY
152 select GENERIC_VDSO_TIME_NS
153 select GUP_GET_PTE_LOW_HIGH if X86_PAE
154 select HARDIRQS_SW_RESEND
155 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
156 select HAVE_ACPI_APEI if ACPI
157 select HAVE_ACPI_APEI_NMI if ACPI
158 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
159 select HAVE_ARCH_AUDITSYSCALL
160 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
161 select HAVE_ARCH_JUMP_LABEL
162 select HAVE_ARCH_JUMP_LABEL_RELATIVE
163 select HAVE_ARCH_KASAN if X86_64
164 select HAVE_ARCH_KASAN_VMALLOC if X86_64
165 select HAVE_ARCH_KFENCE
166 select HAVE_ARCH_KGDB
167 select HAVE_ARCH_MMAP_RND_BITS if MMU
168 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
169 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
170 select HAVE_ARCH_PREL32_RELOCATIONS
171 select HAVE_ARCH_SECCOMP_FILTER
172 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
173 select HAVE_ARCH_STACKLEAK
174 select HAVE_ARCH_TRACEHOOK
175 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
176 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
177 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
178 select HAVE_ARCH_USERFAULTFD_MINOR if X86_64 && USERFAULTFD
179 select HAVE_ARCH_VMAP_STACK if X86_64
180 select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
181 select HAVE_ARCH_WITHIN_STACK_FRAMES
182 select HAVE_ASM_MODVERSIONS
183 select HAVE_CMPXCHG_DOUBLE
184 select HAVE_CMPXCHG_LOCAL
185 select HAVE_CONTEXT_TRACKING if X86_64
186 select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
187 select HAVE_C_RECORDMCOUNT
188 select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
189 select HAVE_DEBUG_KMEMLEAK
190 select HAVE_DMA_CONTIGUOUS
191 select HAVE_DYNAMIC_FTRACE
192 select HAVE_DYNAMIC_FTRACE_WITH_REGS
193 select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
194 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
196 select HAVE_EFFICIENT_UNALIGNED_ACCESS
198 select HAVE_EXIT_THREAD
200 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
201 select HAVE_FTRACE_MCOUNT_RECORD
202 select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
203 select HAVE_FUNCTION_TRACER
204 select HAVE_GCC_PLUGINS
205 select HAVE_HW_BREAKPOINT
206 select HAVE_IOREMAP_PROT
207 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
208 select HAVE_IRQ_TIME_ACCOUNTING
209 select HAVE_KERNEL_BZIP2
210 select HAVE_KERNEL_GZIP
211 select HAVE_KERNEL_LZ4
212 select HAVE_KERNEL_LZMA
213 select HAVE_KERNEL_LZO
214 select HAVE_KERNEL_XZ
215 select HAVE_KERNEL_ZSTD
217 select HAVE_KPROBES_ON_FTRACE
218 select HAVE_FUNCTION_ERROR_INJECTION
219 select HAVE_KRETPROBES
221 select HAVE_LIVEPATCH if X86_64
222 select HAVE_MIXED_BREAKPOINTS_REGS
223 select HAVE_MOD_ARCH_SPECIFIC
227 select HAVE_OPTPROBES
228 select HAVE_PCSPKR_PLATFORM
229 select HAVE_PERF_EVENTS
230 select HAVE_PERF_EVENTS_NMI
231 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
233 select HAVE_PERF_REGS
234 select HAVE_PERF_USER_STACK_DUMP
235 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
236 select HAVE_POSIX_CPU_TIMERS_TASK_WORK
237 select HAVE_REGS_AND_STACK_ACCESS_API
238 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
239 select HAVE_FUNCTION_ARG_ACCESS_API
240 select HAVE_SOFTIRQ_ON_OWN_STACK
241 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
242 select HAVE_STACK_VALIDATION if X86_64
243 select HAVE_STATIC_CALL
244 select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
245 select HAVE_PREEMPT_DYNAMIC
247 select HAVE_SYSCALL_TRACEPOINTS
248 select HAVE_UNSTABLE_SCHED_CLOCK
249 select HAVE_USER_RETURN_NOTIFIER
250 select HAVE_GENERIC_VDSO
251 select HOTPLUG_SMT if SMP
252 select IRQ_FORCED_THREADING
253 select NEED_SG_DMA_LENGTH
254 select PCI_DOMAINS if PCI
255 select PCI_LOCKLESS_CONFIG if PCI
258 select RTC_MC146818_LIB
261 select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
262 select SYSCTL_EXCEPTION_TRACE
263 select THREAD_INFO_IN_TASK
264 select TRACE_IRQFLAGS_SUPPORT
265 select USER_STACKTRACE_SUPPORT
267 select HAVE_ARCH_KCSAN if X86_64
268 select X86_FEATURE_NAMES if PROC_FS
269 select PROC_PID_ARCH_STATUS if PROC_FS
270 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
272 config INSTRUCTION_DECODER
274 depends on KPROBES || PERF_EVENTS || UPROBES
278 default "elf32-i386" if X86_32
279 default "elf64-x86-64" if X86_64
281 config LOCKDEP_SUPPORT
284 config STACKTRACE_SUPPORT
290 config ARCH_MMAP_RND_BITS_MIN
294 config ARCH_MMAP_RND_BITS_MAX
298 config ARCH_MMAP_RND_COMPAT_BITS_MIN
301 config ARCH_MMAP_RND_COMPAT_BITS_MAX
307 config GENERIC_ISA_DMA
309 depends on ISA_DMA_API
314 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
316 config GENERIC_BUG_RELATIVE_POINTERS
319 config ARCH_MAY_HAVE_PC_FDC
321 depends on ISA_DMA_API
323 config GENERIC_CALIBRATE_DELAY
326 config ARCH_HAS_CPU_RELAX
329 config ARCH_HAS_FILTER_PGPROT
332 config HAVE_SETUP_PER_CPU_AREA
335 config NEED_PER_CPU_EMBED_FIRST_CHUNK
338 config NEED_PER_CPU_PAGE_FIRST_CHUNK
341 config ARCH_HIBERNATION_POSSIBLE
346 default 1024 if X86_64
349 config ARCH_SUSPEND_POSSIBLE
352 config ARCH_WANT_GENERAL_HUGETLB
358 config KASAN_SHADOW_OFFSET
361 default 0xdffffc0000000000
363 config HAVE_INTEL_TXT
365 depends on INTEL_IOMMU && ACPI
369 depends on X86_32 && SMP
373 depends on X86_64 && SMP
375 config ARCH_SUPPORTS_UPROBES
378 config FIX_EARLYCON_MEM
381 config DYNAMIC_PHYSICAL_MASK
384 config PGTABLE_LEVELS
386 default 5 if X86_5LEVEL
391 config CC_HAS_SANE_STACKPROTECTOR
393 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
394 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
396 We have to make sure stack protector is unconditionally disabled if
397 the compiler produces broken code or if it does not let us control
398 the segment on 32-bit kernels.
400 menu "Processor type and features"
403 bool "Symmetric multi-processing support"
405 This enables support for systems with more than one CPU. If you have
406 a system with only one CPU, say N. If you have a system with more
409 If you say N here, the kernel will run on uni- and multiprocessor
410 machines, but will use only one CPU of a multiprocessor machine. If
411 you say Y here, the kernel will run on many, but not all,
412 uniprocessor machines. On a uniprocessor machine, the kernel
413 will run faster if you say N here.
415 Note that if you say Y here and choose architecture "586" or
416 "Pentium" under "Processor family", the kernel will not work on 486
417 architectures. Similarly, multiprocessor kernels for the "PPro"
418 architecture may not work on all Pentium based boards.
420 People using multiprocessor machines who say Y here should also say
421 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
422 Management" code will be disabled if you say Y here.
424 See also <file:Documentation/x86/i386/IO-APIC.rst>,
425 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
426 <http://www.tldp.org/docs.html#howto>.
428 If you don't know what to do here, say N.
430 config X86_FEATURE_NAMES
431 bool "Processor feature human-readable names" if EMBEDDED
434 This option compiles in a table of x86 feature bits and corresponding
435 names. This is required to support /proc/cpuinfo and a few kernel
436 messages. You can disable this to save space, at the expense of
437 making those few kernel messages show numeric feature bits instead.
442 bool "Support x2apic"
443 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
445 This enables x2apic support on CPUs that have this feature.
447 This allows 32-bit apic IDs (so it can support very large systems),
448 and accesses the local apic via MSRs not via mmio.
450 If you don't know what to do here, say N.
453 bool "Enable MPS table" if ACPI
455 depends on X86_LOCAL_APIC
457 For old smp systems that do not have proper acpi support. Newer systems
458 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
462 depends on X86_GOLDFISH
465 bool "Avoid speculative indirect branches in kernel"
468 Compile kernel with the retpoline compiler options to guard against
469 kernel-to-user data leaks by avoiding speculative indirect
470 branches. Requires a compiler with -mindirect-branch=thunk-extern
471 support for full protection. The kernel may run slower.
473 config X86_CPU_RESCTRL
474 bool "x86 CPU resource control support"
475 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
477 select PROC_CPU_RESCTRL if PROC_FS
479 Enable x86 CPU resource control support.
481 Provide support for the allocation and monitoring of system resources
484 Intel calls this Intel Resource Director Technology
485 (Intel(R) RDT). More information about RDT can be found in the
486 Intel x86 Architecture Software Developer Manual.
488 AMD calls this AMD Platform Quality of Service (AMD QoS).
489 More information about AMD QoS can be found in the AMD64 Technology
490 Platform Quality of Service Extensions manual.
496 bool "Support for big SMP systems with more than 8 CPUs"
499 This option is needed for the systems that have more than 8 CPUs.
501 config X86_EXTENDED_PLATFORM
502 bool "Support for extended (non-PC) x86 platforms"
505 If you disable this option then the kernel will only support
506 standard PC platforms. (which covers the vast majority of
509 If you enable this option then you'll be able to select support
510 for the following (non-PC) 32 bit x86 platforms:
511 Goldfish (Android emulator)
514 SGI 320/540 (Visual Workstation)
515 STA2X11-based (e.g. Northville)
516 Moorestown MID devices
518 If you have one of these systems, or if you want to build a
519 generic distribution kernel, say Y here - otherwise say N.
523 config X86_EXTENDED_PLATFORM
524 bool "Support for extended (non-PC) x86 platforms"
527 If you disable this option then the kernel will only support
528 standard PC platforms. (which covers the vast majority of
531 If you enable this option then you'll be able to select support
532 for the following (non-PC) 64 bit x86 platforms:
537 If you have one of these systems, or if you want to build a
538 generic distribution kernel, say Y here - otherwise say N.
540 # This is an alphabetically sorted list of 64 bit extended platforms
541 # Please maintain the alphabetic order if and when there are additions
543 bool "Numascale NumaChip"
545 depends on X86_EXTENDED_PLATFORM
548 depends on X86_X2APIC
549 depends on PCI_MMCONFIG
551 Adds support for Numascale NumaChip large-SMP systems. Needed to
552 enable more than ~168 cores.
553 If you don't have one of these, you should say N here.
557 select HYPERVISOR_GUEST
559 depends on X86_64 && PCI
560 depends on X86_EXTENDED_PLATFORM
563 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
564 supposed to run on these EM64T-based machines. Only choose this option
565 if you have one of these machines.
568 bool "SGI Ultraviolet"
570 depends on X86_EXTENDED_PLATFORM
573 depends on KEXEC_CORE
574 depends on X86_X2APIC
577 This option is needed in order to support SGI Ultraviolet systems.
578 If you don't have one of these, you should say N here.
580 # Following is an alphabetically sorted list of 32 bit extended platforms
581 # Please maintain the alphabetic order if and when there are additions
584 bool "Goldfish (Virtual Platform)"
585 depends on X86_EXTENDED_PLATFORM
587 Enable support for the Goldfish virtual platform used primarily
588 for Android development. Unless you are building for the Android
589 Goldfish emulator say N here.
592 bool "CE4100 TV platform"
594 depends on PCI_GODIRECT
595 depends on X86_IO_APIC
597 depends on X86_EXTENDED_PLATFORM
598 select X86_REBOOTFIXUPS
600 select OF_EARLY_FLATTREE
602 Select for the Intel CE media processor (CE4100) SOC.
603 This option compiles in support for the CE4100 SOC for settop
604 boxes and media devices.
607 bool "Intel MID platform support"
608 depends on X86_EXTENDED_PLATFORM
609 depends on X86_PLATFORM_DEVICES
611 depends on X86_64 || (PCI_GOANY && X86_32)
612 depends on X86_IO_APIC
617 Select to build a kernel capable of supporting Intel MID (Mobile
618 Internet Device) platform systems which do not have the PCI legacy
619 interfaces. If you are building for a PC class system say N here.
621 Intel MID platforms are based on an Intel processor and chipset which
622 consume less power than most of the x86 derivatives.
624 config X86_INTEL_QUARK
625 bool "Intel Quark platform support"
627 depends on X86_EXTENDED_PLATFORM
628 depends on X86_PLATFORM_DEVICES
632 depends on X86_IO_APIC
637 Select to include support for Quark X1000 SoC.
638 Say Y here if you have a Quark based system such as the Arduino
639 compatible Intel Galileo.
641 config X86_INTEL_LPSS
642 bool "Intel Low Power Subsystem Support"
643 depends on X86 && ACPI && PCI
648 Select to build support for Intel Low Power Subsystem such as
649 found on Intel Lynxpoint PCH. Selecting this option enables
650 things like clock tree (common clock framework) and pincontrol
651 which are needed by the LPSS peripheral drivers.
653 config X86_AMD_PLATFORM_DEVICE
654 bool "AMD ACPI2Platform devices support"
659 Select to interpret AMD specific ACPI device to platform device
660 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
661 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
662 implemented under PINCTRL subsystem.
665 tristate "Intel SoC IOSF Sideband support for SoC platforms"
668 This option enables sideband register access support for Intel SoC
669 platforms. On these platforms the IOSF sideband is used in lieu of
670 MSR's for some register accesses, mostly but not limited to thermal
671 and power. Drivers may query the availability of this device to
672 determine if they need the sideband in order to work on these
673 platforms. The sideband is available on the following SoC products.
674 This list is not meant to be exclusive.
679 You should say Y if you are running a kernel on one of these SoC's.
681 config IOSF_MBI_DEBUG
682 bool "Enable IOSF sideband access through debugfs"
683 depends on IOSF_MBI && DEBUG_FS
685 Select this option to expose the IOSF sideband access registers (MCR,
686 MDR, MCRX) through debugfs to write and read register information from
687 different units on the SoC. This is most useful for obtaining device
688 state information for debug and analysis. As this is a general access
689 mechanism, users of this option would have specific knowledge of the
690 device they want to access.
692 If you don't require the option or are in doubt, say N.
695 bool "RDC R-321x SoC"
697 depends on X86_EXTENDED_PLATFORM
699 select X86_REBOOTFIXUPS
701 This option is needed for RDC R-321x system-on-chip, also known
703 If you don't have one of these chips, you should say N here.
705 config X86_32_NON_STANDARD
706 bool "Support non-standard 32-bit SMP architectures"
707 depends on X86_32 && SMP
708 depends on X86_EXTENDED_PLATFORM
710 This option compiles in the bigsmp and STA2X11 default
711 subarchitectures. It is intended for a generic binary
712 kernel. If you select them all, kernel will probe it one by
713 one and will fallback to default.
715 # Alphabetically sorted list of Non standard 32 bit platforms
717 config X86_SUPPORTS_MEMORY_FAILURE
719 # MCE code calls memory_failure():
721 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
722 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
723 depends on X86_64 || !SPARSEMEM
724 select ARCH_SUPPORTS_MEMORY_FAILURE
727 bool "STA2X11 Companion Chip Support"
728 depends on X86_32_NON_STANDARD && PCI
733 This adds support for boards based on the STA2X11 IO-Hub,
734 a.k.a. "ConneXt". The chip is used in place of the standard
735 PC chipset, so all "standard" peripherals are missing. If this
736 option is selected the kernel will still be able to boot on
737 standard PC machines.
740 tristate "Eurobraille/Iris poweroff module"
743 The Iris machines from EuroBraille do not have APM or ACPI support
744 to shut themselves down properly. A special I/O sequence is
745 needed to do so, which is what this module does at
748 This is only for Iris machines from EuroBraille.
752 config SCHED_OMIT_FRAME_POINTER
754 prompt "Single-depth WCHAN output"
757 Calculate simpler /proc/<PID>/wchan values. If this option
758 is disabled then wchan values will recurse back to the
759 caller function. This provides more accurate wchan values,
760 at the expense of slightly more scheduling overhead.
762 If in doubt, say "Y".
764 menuconfig HYPERVISOR_GUEST
765 bool "Linux guest support"
767 Say Y here to enable options for running Linux under various hyper-
768 visors. This option enables basic hypervisor detection and platform
771 If you say N, all options in this submenu will be skipped and
772 disabled, and Linux guest support won't be built in.
777 bool "Enable paravirtualization code"
778 depends on HAVE_STATIC_CALL
780 This changes the kernel so it can modify itself when it is run
781 under a hypervisor, potentially improving performance significantly
782 over full virtualization. However, when run without a hypervisor
783 the kernel is theoretically slower and slightly larger.
788 config PARAVIRT_DEBUG
789 bool "paravirt-ops debugging"
790 depends on PARAVIRT && DEBUG_KERNEL
792 Enable to debug paravirt_ops internals. Specifically, BUG if
793 a paravirt_op is missing when it is called.
795 config PARAVIRT_SPINLOCKS
796 bool "Paravirtualization layer for spinlocks"
797 depends on PARAVIRT && SMP
799 Paravirtualized spinlocks allow a pvops backend to replace the
800 spinlock implementation with something virtualization-friendly
801 (for example, block the virtual CPU rather than spinning).
803 It has a minimal impact on native kernels and gives a nice performance
804 benefit on paravirtualized KVM / Xen kernels.
806 If you are unsure how to answer this question, answer Y.
808 config X86_HV_CALLBACK_VECTOR
811 source "arch/x86/xen/Kconfig"
814 bool "KVM Guest support (including kvmclock)"
816 select PARAVIRT_CLOCK
817 select ARCH_CPUIDLE_HALTPOLL
818 select X86_HV_CALLBACK_VECTOR
821 This option enables various optimizations for running under the KVM
822 hypervisor. It includes a paravirtualized clock, so that instead
823 of relying on a PIT (or probably other) emulation by the
824 underlying device model, the host provides the guest with
825 timing infrastructure such as time of day, and system time
827 config ARCH_CPUIDLE_HALTPOLL
829 prompt "Disable host haltpoll when loading haltpoll driver"
831 If virtualized under KVM, disable host haltpoll.
834 bool "Support for running PVH guests"
836 This option enables the PVH entry point for guest virtual machines
837 as specified in the x86/HVM direct boot ABI.
839 config PARAVIRT_TIME_ACCOUNTING
840 bool "Paravirtual steal time accounting"
843 Select this option to enable fine granularity task steal time
844 accounting. Time spent executing other tasks in parallel with
845 the current vCPU is discounted from the vCPU power. To account for
846 that, there can be a small performance impact.
848 If in doubt, say N here.
850 config PARAVIRT_CLOCK
853 config JAILHOUSE_GUEST
854 bool "Jailhouse non-root cell support"
855 depends on X86_64 && PCI
858 This option allows to run Linux as guest in a Jailhouse non-root
859 cell. You can leave this option disabled if you only want to start
860 Jailhouse and run Linux afterwards in the root cell.
863 bool "ACRN Guest support"
865 select X86_HV_CALLBACK_VECTOR
867 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
868 a flexible, lightweight reference open-source hypervisor, built with
869 real-time and safety-criticality in mind. It is built for embedded
870 IOT with small footprint and real-time features. More details can be
871 found in https://projectacrn.org/.
873 endif #HYPERVISOR_GUEST
875 source "arch/x86/Kconfig.cpu"
879 prompt "HPET Timer Support" if X86_32
881 Use the IA-PC HPET (High Precision Event Timer) to manage
882 time in preference to the PIT and RTC, if a HPET is
884 HPET is the next generation timer replacing legacy 8254s.
885 The HPET provides a stable time base on SMP
886 systems, unlike the TSC, but it is more expensive to access,
887 as it is off-chip. The interface used is documented
888 in the HPET spec, revision 1.
890 You can safely choose Y here. However, HPET will only be
891 activated if the platform and the BIOS support this feature.
892 Otherwise the 8254 will be used for timing services.
894 Choose N to continue using the legacy 8254 timer.
896 config HPET_EMULATE_RTC
898 depends on HPET_TIMER && (RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
900 # Mark as expert because too many people got it wrong.
901 # The code disables itself when not needed.
904 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
905 bool "Enable DMI scanning" if EXPERT
907 Enabled scanning of DMI to identify machine quirks. Say Y
908 here unless you have verified that your setup is not
909 affected by entries in the DMI blacklist. Required by PNP
913 bool "Old AMD GART IOMMU support"
917 depends on X86_64 && PCI && AMD_NB
919 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
920 GART based hardware IOMMUs.
922 The GART supports full DMA access for devices with 32-bit access
923 limitations, on systems with more than 3 GB. This is usually needed
924 for USB, sound, many IDE/SATA chipsets and some other devices.
926 Newer systems typically have a modern AMD IOMMU, supported via
927 the CONFIG_AMD_IOMMU=y config option.
929 In normal configurations this driver is only active when needed:
930 there's more than 3 GB of memory and the system contains a
931 32-bit limited device.
936 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
937 depends on X86_64 && SMP && DEBUG_KERNEL
938 select CPUMASK_OFFSTACK
940 Enable maximum number of CPUS and NUMA Nodes for this architecture.
944 # The maximum number of CPUs supported:
946 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
947 # and which can be configured interactively in the
948 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
950 # The ranges are different on 32-bit and 64-bit kernels, depending on
951 # hardware capabilities and scalability features of the kernel.
953 # ( If MAXSMP is enabled we just use the highest possible value and disable
954 # interactive configuration. )
957 config NR_CPUS_RANGE_BEGIN
959 default NR_CPUS_RANGE_END if MAXSMP
963 config NR_CPUS_RANGE_END
966 default 64 if SMP && X86_BIGSMP
967 default 8 if SMP && !X86_BIGSMP
970 config NR_CPUS_RANGE_END
973 default 8192 if SMP && CPUMASK_OFFSTACK
974 default 512 if SMP && !CPUMASK_OFFSTACK
977 config NR_CPUS_DEFAULT
980 default 32 if X86_BIGSMP
984 config NR_CPUS_DEFAULT
987 default 8192 if MAXSMP
992 int "Maximum number of CPUs" if SMP && !MAXSMP
993 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
994 default NR_CPUS_DEFAULT
996 This allows you to specify the maximum number of CPUs which this
997 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
998 supported value is 8192, otherwise the maximum value is 512. The
999 minimum value which makes sense is 2.
1001 This is purely to save memory: each supported CPU adds about 8KB
1002 to the kernel image.
1004 config SCHED_CLUSTER
1005 bool "Cluster scheduler support"
1009 Cluster scheduler support improves the CPU scheduler's decision
1010 making when dealing with machines that have clusters of CPUs.
1011 Cluster usually means a couple of CPUs which are placed closely
1012 by sharing mid-level caches, last-level cache tags or internal
1020 prompt "Multi-core scheduler support"
1023 Multi-core scheduler support improves the CPU scheduler's decision
1024 making when dealing with multi-core CPU chips at a cost of slightly
1025 increased overhead in some places. If unsure say N here.
1027 config SCHED_MC_PRIO
1028 bool "CPU core priorities scheduler support"
1029 depends on SCHED_MC && CPU_SUP_INTEL
1030 select X86_INTEL_PSTATE
1034 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1035 core ordering determined at manufacturing time, which allows
1036 certain cores to reach higher turbo frequencies (when running
1037 single threaded workloads) than others.
1039 Enabling this kernel feature teaches the scheduler about
1040 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1041 scheduler's CPU selection logic accordingly, so that higher
1042 overall system performance can be achieved.
1044 This feature will have no effect on CPUs without this feature.
1046 If unsure say Y here.
1050 depends on !SMP && X86_LOCAL_APIC
1053 bool "Local APIC support on uniprocessors" if !PCI_MSI
1055 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1057 A local APIC (Advanced Programmable Interrupt Controller) is an
1058 integrated interrupt controller in the CPU. If you have a single-CPU
1059 system which has a processor with a local APIC, you can say Y here to
1060 enable and use it. If you say Y here even though your machine doesn't
1061 have a local APIC, then the kernel will still run with no slowdown at
1062 all. The local APIC supports CPU-generated self-interrupts (timer,
1063 performance counters), and the NMI watchdog which detects hard
1066 config X86_UP_IOAPIC
1067 bool "IO-APIC support on uniprocessors"
1068 depends on X86_UP_APIC
1070 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1071 SMP-capable replacement for PC-style interrupt controllers. Most
1072 SMP systems and many recent uniprocessor systems have one.
1074 If you have a single-CPU system with an IO-APIC, you can say Y here
1075 to use it. If you say Y here even though your machine doesn't have
1076 an IO-APIC, then the kernel will still run with no slowdown at all.
1078 config X86_LOCAL_APIC
1080 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1081 select IRQ_DOMAIN_HIERARCHY
1082 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1086 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1088 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1089 bool "Reroute for broken boot IRQs"
1090 depends on X86_IO_APIC
1092 This option enables a workaround that fixes a source of
1093 spurious interrupts. This is recommended when threaded
1094 interrupt handling is used on systems where the generation of
1095 superfluous "boot interrupts" cannot be disabled.
1097 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1098 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1099 kernel does during interrupt handling). On chipsets where this
1100 boot IRQ generation cannot be disabled, this workaround keeps
1101 the original IRQ line masked so that only the equivalent "boot
1102 IRQ" is delivered to the CPUs. The workaround also tells the
1103 kernel to set up the IRQ handler on the boot IRQ line. In this
1104 way only one interrupt is delivered to the kernel. Otherwise
1105 the spurious second interrupt may cause the kernel to bring
1106 down (vital) interrupt lines.
1108 Only affects "broken" chipsets. Interrupt sharing may be
1109 increased on these systems.
1112 bool "Machine Check / overheating reporting"
1113 select GENERIC_ALLOCATOR
1116 Machine Check support allows the processor to notify the
1117 kernel if it detects a problem (e.g. overheating, data corruption).
1118 The action the kernel takes depends on the severity of the problem,
1119 ranging from warning messages to halting the machine.
1121 config X86_MCELOG_LEGACY
1122 bool "Support for deprecated /dev/mcelog character device"
1125 Enable support for /dev/mcelog which is needed by the old mcelog
1126 userspace logging daemon. Consider switching to the new generation
1129 config X86_MCE_INTEL
1131 prompt "Intel MCE features"
1132 depends on X86_MCE && X86_LOCAL_APIC
1134 Additional support for intel specific MCE features such as
1135 the thermal monitor.
1139 prompt "AMD MCE features"
1140 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1142 Additional support for AMD specific MCE features such as
1143 the DRAM Error Threshold.
1145 config X86_ANCIENT_MCE
1146 bool "Support for old Pentium 5 / WinChip machine checks"
1147 depends on X86_32 && X86_MCE
1149 Include support for machine check handling on old Pentium 5 or WinChip
1150 systems. These typically need to be enabled explicitly on the command
1153 config X86_MCE_THRESHOLD
1154 depends on X86_MCE_AMD || X86_MCE_INTEL
1157 config X86_MCE_INJECT
1158 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1159 tristate "Machine check injector support"
1161 Provide support for injecting machine checks for testing purposes.
1162 If you don't know what a machine check is and you don't do kernel
1163 QA it is safe to say n.
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"
1272 select SENSORS_DELL_SMM
1274 This option enables legacy /proc/i8k userspace interface in hwmon
1275 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1276 temperature and allows controlling fan speeds of Dell laptops via
1277 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1278 it reports also power and hotkey status. For fan speed control is
1279 needed userspace package i8kutils.
1281 Say Y if you intend to run this kernel on old Dell laptops or want to
1282 use userspace package i8kutils.
1285 config X86_REBOOTFIXUPS
1286 bool "Enable X86 board specific fixups for reboot"
1289 This enables chipset and/or board specific fixups to be done
1290 in order to get reboot to work correctly. This is only needed on
1291 some combinations of hardware and BIOS. The symptom, for which
1292 this config is intended, is when reboot ends with a stalled/hung
1295 Currently, the only fixup is for the Geode machines using
1296 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1298 Say Y if you want to enable the fixup. Currently, it's safe to
1299 enable this option even if you don't need it.
1303 bool "CPU microcode loading support"
1305 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1307 If you say Y here, you will be able to update the microcode on
1308 Intel and AMD processors. The Intel support is for the IA32 family,
1309 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1310 AMD support is for families 0x10 and later. You will obviously need
1311 the actual microcode binary data itself which is not shipped with
1314 The preferred method to load microcode from a detached initrd is described
1315 in Documentation/x86/microcode.rst. For that you need to enable
1316 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1317 initrd for microcode blobs.
1319 In addition, you can build the microcode into the kernel. For that you
1320 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1323 config MICROCODE_INTEL
1324 bool "Intel microcode loading support"
1325 depends on MICROCODE
1328 This options enables microcode patch loading support for Intel
1331 For the current Intel microcode data package go to
1332 <https://downloadcenter.intel.com> and search for
1333 'Linux Processor Microcode Data File'.
1335 config MICROCODE_AMD
1336 bool "AMD microcode loading support"
1337 depends on MICROCODE
1339 If you select this option, microcode patch loading support for AMD
1340 processors will be enabled.
1342 config MICROCODE_OLD_INTERFACE
1343 bool "Ancient loading interface (DEPRECATED)"
1345 depends on MICROCODE
1347 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1348 which was used by userspace tools like iucode_tool and microcode.ctl.
1349 It is inadequate because it runs too late to be able to properly
1350 load microcode on a machine and it needs special tools. Instead, you
1351 should've switched to the early loading method with the initrd or
1352 builtin microcode by now: Documentation/x86/microcode.rst
1355 tristate "/dev/cpu/*/msr - Model-specific register support"
1357 This device gives privileged processes access to the x86
1358 Model-Specific Registers (MSRs). It is a character device with
1359 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1360 MSR accesses are directed to a specific CPU on multi-processor
1364 tristate "/dev/cpu/*/cpuid - CPU information support"
1366 This device gives processes access to the x86 CPUID instruction to
1367 be executed on a specific processor. It is a character device
1368 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1372 prompt "High Memory Support"
1379 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1380 However, the address space of 32-bit x86 processors is only 4
1381 Gigabytes large. That means that, if you have a large amount of
1382 physical memory, not all of it can be "permanently mapped" by the
1383 kernel. The physical memory that's not permanently mapped is called
1386 If you are compiling a kernel which will never run on a machine with
1387 more than 1 Gigabyte total physical RAM, answer "off" here (default
1388 choice and suitable for most users). This will result in a "3GB/1GB"
1389 split: 3GB are mapped so that each process sees a 3GB virtual memory
1390 space and the remaining part of the 4GB virtual memory space is used
1391 by the kernel to permanently map as much physical memory as
1394 If the machine has between 1 and 4 Gigabytes physical RAM, then
1397 If more than 4 Gigabytes is used then answer "64GB" here. This
1398 selection turns Intel PAE (Physical Address Extension) mode on.
1399 PAE implements 3-level paging on IA32 processors. PAE is fully
1400 supported by Linux, PAE mode is implemented on all recent Intel
1401 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1402 then the kernel will not boot on CPUs that don't support PAE!
1404 The actual amount of total physical memory will either be
1405 auto detected or can be forced by using a kernel command line option
1406 such as "mem=256M". (Try "man bootparam" or see the documentation of
1407 your boot loader (lilo or loadlin) about how to pass options to the
1408 kernel at boot time.)
1410 If unsure, say "off".
1415 Select this if you have a 32-bit processor and between 1 and 4
1416 gigabytes of physical RAM.
1420 depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
1423 Select this if you have a 32-bit processor and more than 4
1424 gigabytes of physical RAM.
1429 prompt "Memory split" if EXPERT
1433 Select the desired split between kernel and user memory.
1435 If the address range available to the kernel is less than the
1436 physical memory installed, the remaining memory will be available
1437 as "high memory". Accessing high memory is a little more costly
1438 than low memory, as it needs to be mapped into the kernel first.
1439 Note that increasing the kernel address space limits the range
1440 available to user programs, making the address space there
1441 tighter. Selecting anything other than the default 3G/1G split
1442 will also likely make your kernel incompatible with binary-only
1445 If you are not absolutely sure what you are doing, leave this
1449 bool "3G/1G user/kernel split"
1450 config VMSPLIT_3G_OPT
1452 bool "3G/1G user/kernel split (for full 1G low memory)"
1454 bool "2G/2G user/kernel split"
1455 config VMSPLIT_2G_OPT
1457 bool "2G/2G user/kernel split (for full 2G low memory)"
1459 bool "1G/3G user/kernel split"
1464 default 0xB0000000 if VMSPLIT_3G_OPT
1465 default 0x80000000 if VMSPLIT_2G
1466 default 0x78000000 if VMSPLIT_2G_OPT
1467 default 0x40000000 if VMSPLIT_1G
1473 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1476 bool "PAE (Physical Address Extension) Support"
1477 depends on X86_32 && !HIGHMEM4G
1478 select PHYS_ADDR_T_64BIT
1481 PAE is required for NX support, and furthermore enables
1482 larger swapspace support for non-overcommit purposes. It
1483 has the cost of more pagetable lookup overhead, and also
1484 consumes more pagetable space per process.
1487 bool "Enable 5-level page tables support"
1489 select DYNAMIC_MEMORY_LAYOUT
1490 select SPARSEMEM_VMEMMAP
1493 5-level paging enables access to larger address space:
1494 upto 128 PiB of virtual address space and 4 PiB of
1495 physical address space.
1497 It will be supported by future Intel CPUs.
1499 A kernel with the option enabled can be booted on machines that
1500 support 4- or 5-level paging.
1502 See Documentation/x86/x86_64/5level-paging.rst for more
1507 config X86_DIRECT_GBPAGES
1511 Certain kernel features effectively disable kernel
1512 linear 1 GB mappings (even if the CPU otherwise
1513 supports them), so don't confuse the user by printing
1514 that we have them enabled.
1516 config X86_CPA_STATISTICS
1517 bool "Enable statistic for Change Page Attribute"
1520 Expose statistics about the Change Page Attribute mechanism, which
1521 helps to determine the effectiveness of preserving large and huge
1522 page mappings when mapping protections are changed.
1524 config AMD_MEM_ENCRYPT
1525 bool "AMD Secure Memory Encryption (SME) support"
1526 depends on X86_64 && CPU_SUP_AMD
1527 select DMA_COHERENT_POOL
1528 select DYNAMIC_PHYSICAL_MASK
1529 select ARCH_USE_MEMREMAP_PROT
1530 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1531 select INSTRUCTION_DECODER
1532 select ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS
1533 select ARCH_HAS_CC_PLATFORM
1535 Say yes to enable support for the encryption of system memory.
1536 This requires an AMD processor that supports Secure Memory
1539 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1540 bool "Activate AMD Secure Memory Encryption (SME) by default"
1541 depends on AMD_MEM_ENCRYPT
1543 Say yes to have system memory encrypted by default if running on
1544 an AMD processor that supports Secure Memory Encryption (SME).
1546 If set to Y, then the encryption of system memory can be
1547 deactivated with the mem_encrypt=off command line option.
1549 If set to N, then the encryption of system memory can be
1550 activated with the mem_encrypt=on command line option.
1552 # Common NUMA Features
1554 bool "NUMA Memory Allocation and Scheduler Support"
1556 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1557 default y if X86_BIGSMP
1559 Enable NUMA (Non-Uniform Memory Access) support.
1561 The kernel will try to allocate memory used by a CPU on the
1562 local memory controller of the CPU and add some more
1563 NUMA awareness to the kernel.
1565 For 64-bit this is recommended if the system is Intel Core i7
1566 (or later), AMD Opteron, or EM64T NUMA.
1568 For 32-bit this is only needed if you boot a 32-bit
1569 kernel on a 64-bit NUMA platform.
1571 Otherwise, you should say N.
1575 prompt "Old style AMD Opteron NUMA detection"
1576 depends on X86_64 && NUMA && PCI
1578 Enable AMD NUMA node topology detection. You should say Y here if
1579 you have a multi processor AMD system. This uses an old method to
1580 read the NUMA configuration directly from the builtin Northbridge
1581 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1582 which also takes priority if both are compiled in.
1584 config X86_64_ACPI_NUMA
1586 prompt "ACPI NUMA detection"
1587 depends on X86_64 && NUMA && ACPI && PCI
1590 Enable ACPI SRAT based node topology detection.
1593 bool "NUMA emulation"
1596 Enable NUMA emulation. A flat machine will be split
1597 into virtual nodes when booted with "numa=fake=N", where N is the
1598 number of nodes. This is only useful for debugging.
1601 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1603 default "10" if MAXSMP
1604 default "6" if X86_64
1608 Specify the maximum number of NUMA Nodes available on the target
1609 system. Increases memory reserved to accommodate various tables.
1611 config ARCH_FLATMEM_ENABLE
1613 depends on X86_32 && !NUMA
1615 config ARCH_SPARSEMEM_ENABLE
1617 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1618 select SPARSEMEM_STATIC if X86_32
1619 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1621 config ARCH_SPARSEMEM_DEFAULT
1622 def_bool X86_64 || (NUMA && X86_32)
1624 config ARCH_SELECT_MEMORY_MODEL
1626 depends on ARCH_SPARSEMEM_ENABLE
1628 config ARCH_MEMORY_PROBE
1629 bool "Enable sysfs memory/probe interface"
1630 depends on MEMORY_HOTPLUG
1632 This option enables a sysfs memory/probe interface for testing.
1633 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1634 If you are unsure how to answer this question, answer N.
1636 config ARCH_PROC_KCORE_TEXT
1638 depends on X86_64 && PROC_KCORE
1640 config ILLEGAL_POINTER_VALUE
1643 default 0xdead000000000000 if X86_64
1645 config X86_PMEM_LEGACY_DEVICE
1648 config X86_PMEM_LEGACY
1649 tristate "Support non-standard NVDIMMs and ADR protected memory"
1650 depends on PHYS_ADDR_T_64BIT
1652 select X86_PMEM_LEGACY_DEVICE
1653 select NUMA_KEEP_MEMINFO if NUMA
1656 Treat memory marked using the non-standard e820 type of 12 as used
1657 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1658 The kernel will offer these regions to the 'pmem' driver so
1659 they can be used for persistent storage.
1664 bool "Allocate 3rd-level pagetables from highmem"
1667 The VM uses one page table entry for each page of physical memory.
1668 For systems with a lot of RAM, this can be wasteful of precious
1669 low memory. Setting this option will put user-space page table
1670 entries in high memory.
1672 config X86_CHECK_BIOS_CORRUPTION
1673 bool "Check for low memory corruption"
1675 Periodically check for memory corruption in low memory, which
1676 is suspected to be caused by BIOS. Even when enabled in the
1677 configuration, it is disabled at runtime. Enable it by
1678 setting "memory_corruption_check=1" on the kernel command
1679 line. By default it scans the low 64k of memory every 60
1680 seconds; see the memory_corruption_check_size and
1681 memory_corruption_check_period parameters in
1682 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1684 When enabled with the default parameters, this option has
1685 almost no overhead, as it reserves a relatively small amount
1686 of memory and scans it infrequently. It both detects corruption
1687 and prevents it from affecting the running system.
1689 It is, however, intended as a diagnostic tool; if repeatable
1690 BIOS-originated corruption always affects the same memory,
1691 you can use memmap= to prevent the kernel from using that
1694 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1695 bool "Set the default setting of memory_corruption_check"
1696 depends on X86_CHECK_BIOS_CORRUPTION
1699 Set whether the default state of memory_corruption_check is
1702 config MATH_EMULATION
1704 depends on MODIFY_LDT_SYSCALL
1705 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1707 Linux can emulate a math coprocessor (used for floating point
1708 operations) if you don't have one. 486DX and Pentium processors have
1709 a math coprocessor built in, 486SX and 386 do not, unless you added
1710 a 487DX or 387, respectively. (The messages during boot time can
1711 give you some hints here ["man dmesg"].) Everyone needs either a
1712 coprocessor or this emulation.
1714 If you don't have a math coprocessor, you need to say Y here; if you
1715 say Y here even though you have a coprocessor, the coprocessor will
1716 be used nevertheless. (This behavior can be changed with the kernel
1717 command line option "no387", which comes handy if your coprocessor
1718 is broken. Try "man bootparam" or see the documentation of your boot
1719 loader (lilo or loadlin) about how to pass options to the kernel at
1720 boot time.) This means that it is a good idea to say Y here if you
1721 intend to use this kernel on different machines.
1723 More information about the internals of the Linux math coprocessor
1724 emulation can be found in <file:arch/x86/math-emu/README>.
1726 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1727 kernel, it won't hurt.
1731 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1733 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1734 the Memory Type Range Registers (MTRRs) may be used to control
1735 processor access to memory ranges. This is most useful if you have
1736 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1737 allows bus write transfers to be combined into a larger transfer
1738 before bursting over the PCI/AGP bus. This can increase performance
1739 of image write operations 2.5 times or more. Saying Y here creates a
1740 /proc/mtrr file which may be used to manipulate your processor's
1741 MTRRs. Typically the X server should use this.
1743 This code has a reasonably generic interface so that similar
1744 control registers on other processors can be easily supported
1747 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1748 Registers (ARRs) which provide a similar functionality to MTRRs. For
1749 these, the ARRs are used to emulate the MTRRs.
1750 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1751 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1752 write-combining. All of these processors are supported by this code
1753 and it makes sense to say Y here if you have one of them.
1755 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1756 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1757 can lead to all sorts of problems, so it's good to say Y here.
1759 You can safely say Y even if your machine doesn't have MTRRs, you'll
1760 just add about 9 KB to your kernel.
1762 See <file:Documentation/x86/mtrr.rst> for more information.
1764 config MTRR_SANITIZER
1766 prompt "MTRR cleanup support"
1769 Convert MTRR layout from continuous to discrete, so X drivers can
1770 add writeback entries.
1772 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1773 The largest mtrr entry size for a continuous block can be set with
1778 config MTRR_SANITIZER_ENABLE_DEFAULT
1779 int "MTRR cleanup enable value (0-1)"
1782 depends on MTRR_SANITIZER
1784 Enable mtrr cleanup default value
1786 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1787 int "MTRR cleanup spare reg num (0-7)"
1790 depends on MTRR_SANITIZER
1792 mtrr cleanup spare entries default, it can be changed via
1793 mtrr_spare_reg_nr=N on the kernel command line.
1797 prompt "x86 PAT support" if EXPERT
1800 Use PAT attributes to setup page level cache control.
1802 PATs are the modern equivalents of MTRRs and are much more
1803 flexible than MTRRs.
1805 Say N here if you see bootup problems (boot crash, boot hang,
1806 spontaneous reboots) or a non-working video driver.
1810 config ARCH_USES_PG_UNCACHED
1816 prompt "x86 architectural random number generator" if EXPERT
1818 Enable the x86 architectural RDRAND instruction
1819 (Intel Bull Mountain technology) to generate random numbers.
1820 If supported, this is a high bandwidth, cryptographically
1821 secure hardware random number generator.
1825 prompt "Supervisor Mode Access Prevention" if EXPERT
1827 Supervisor Mode Access Prevention (SMAP) is a security
1828 feature in newer Intel processors. There is a small
1829 performance cost if this enabled and turned on; there is
1830 also a small increase in the kernel size if this is enabled.
1836 prompt "User Mode Instruction Prevention" if EXPERT
1838 User Mode Instruction Prevention (UMIP) is a security feature in
1839 some x86 processors. If enabled, a general protection fault is
1840 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1841 executed in user mode. These instructions unnecessarily expose
1842 information about the hardware state.
1844 The vast majority of applications do not use these instructions.
1845 For the very few that do, software emulation is provided in
1846 specific cases in protected and virtual-8086 modes. Emulated
1849 config X86_INTEL_MEMORY_PROTECTION_KEYS
1850 prompt "Memory Protection Keys"
1852 # Note: only available in 64-bit mode
1853 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1854 select ARCH_USES_HIGH_VMA_FLAGS
1855 select ARCH_HAS_PKEYS
1857 Memory Protection Keys provides a mechanism for enforcing
1858 page-based protections, but without requiring modification of the
1859 page tables when an application changes protection domains.
1861 For details, see Documentation/core-api/protection-keys.rst
1866 prompt "TSX enable mode"
1867 depends on CPU_SUP_INTEL
1868 default X86_INTEL_TSX_MODE_OFF
1870 Intel's TSX (Transactional Synchronization Extensions) feature
1871 allows to optimize locking protocols through lock elision which
1872 can lead to a noticeable performance boost.
1874 On the other hand it has been shown that TSX can be exploited
1875 to form side channel attacks (e.g. TAA) and chances are there
1876 will be more of those attacks discovered in the future.
1878 Therefore TSX is not enabled by default (aka tsx=off). An admin
1879 might override this decision by tsx=on the command line parameter.
1880 Even with TSX enabled, the kernel will attempt to enable the best
1881 possible TAA mitigation setting depending on the microcode available
1882 for the particular machine.
1884 This option allows to set the default tsx mode between tsx=on, =off
1885 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1888 Say off if not sure, auto if TSX is in use but it should be used on safe
1889 platforms or on if TSX is in use and the security aspect of tsx is not
1892 config X86_INTEL_TSX_MODE_OFF
1895 TSX is disabled if possible - equals to tsx=off command line parameter.
1897 config X86_INTEL_TSX_MODE_ON
1900 TSX is always enabled on TSX capable HW - equals the tsx=on command
1903 config X86_INTEL_TSX_MODE_AUTO
1906 TSX is enabled on TSX capable HW that is believed to be safe against
1907 side channel attacks- equals the tsx=auto command line parameter.
1911 bool "Software Guard eXtensions (SGX)"
1912 depends on X86_64 && CPU_SUP_INTEL
1914 depends on CRYPTO_SHA256=y
1917 select NUMA_KEEP_MEMINFO if NUMA
1919 Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
1920 that can be used by applications to set aside private regions of code
1921 and data, referred to as enclaves. An enclave's private memory can
1922 only be accessed by code running within the enclave. Accesses from
1923 outside the enclave, including other enclaves, are disallowed by
1929 bool "EFI runtime service support"
1932 select EFI_RUNTIME_WRAPPERS
1934 This enables the kernel to use EFI runtime services that are
1935 available (such as the EFI variable services).
1937 This option is only useful on systems that have EFI firmware.
1938 In addition, you should use the latest ELILO loader available
1939 at <http://elilo.sourceforge.net> in order to take advantage
1940 of EFI runtime services. However, even with this option, the
1941 resultant kernel should continue to boot on existing non-EFI
1945 bool "EFI stub support"
1946 depends on EFI && !X86_USE_3DNOW
1947 depends on $(cc-option,-mabi=ms) || X86_32
1950 This kernel feature allows a bzImage to be loaded directly
1951 by EFI firmware without the use of a bootloader.
1953 See Documentation/admin-guide/efi-stub.rst for more information.
1956 bool "EFI mixed-mode support"
1957 depends on EFI_STUB && X86_64
1959 Enabling this feature allows a 64-bit kernel to be booted
1960 on a 32-bit firmware, provided that your CPU supports 64-bit
1963 Note that it is not possible to boot a mixed-mode enabled
1964 kernel via the EFI boot stub - a bootloader that supports
1965 the EFI handover protocol must be used.
1969 source "kernel/Kconfig.hz"
1972 bool "kexec system call"
1975 kexec is a system call that implements the ability to shutdown your
1976 current kernel, and to start another kernel. It is like a reboot
1977 but it is independent of the system firmware. And like a reboot
1978 you can start any kernel with it, not just Linux.
1980 The name comes from the similarity to the exec system call.
1982 It is an ongoing process to be certain the hardware in a machine
1983 is properly shutdown, so do not be surprised if this code does not
1984 initially work for you. As of this writing the exact hardware
1985 interface is strongly in flux, so no good recommendation can be
1989 bool "kexec file based system call"
1994 depends on CRYPTO_SHA256=y
1996 This is new version of kexec system call. This system call is
1997 file based and takes file descriptors as system call argument
1998 for kernel and initramfs as opposed to list of segments as
1999 accepted by previous system call.
2001 config ARCH_HAS_KEXEC_PURGATORY
2005 bool "Verify kernel signature during kexec_file_load() syscall"
2006 depends on KEXEC_FILE
2009 This option makes the kexec_file_load() syscall check for a valid
2010 signature of the kernel image. The image can still be loaded without
2011 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2012 there's a signature that we can check, then it must be valid.
2014 In addition to this option, you need to enable signature
2015 verification for the corresponding kernel image type being
2016 loaded in order for this to work.
2018 config KEXEC_SIG_FORCE
2019 bool "Require a valid signature in kexec_file_load() syscall"
2020 depends on KEXEC_SIG
2022 This option makes kernel signature verification mandatory for
2023 the kexec_file_load() syscall.
2025 config KEXEC_BZIMAGE_VERIFY_SIG
2026 bool "Enable bzImage signature verification support"
2027 depends on KEXEC_SIG
2028 depends on SIGNED_PE_FILE_VERIFICATION
2029 select SYSTEM_TRUSTED_KEYRING
2031 Enable bzImage signature verification support.
2034 bool "kernel crash dumps"
2035 depends on X86_64 || (X86_32 && HIGHMEM)
2037 Generate crash dump after being started by kexec.
2038 This should be normally only set in special crash dump kernels
2039 which are loaded in the main kernel with kexec-tools into
2040 a specially reserved region and then later executed after
2041 a crash by kdump/kexec. The crash dump kernel must be compiled
2042 to a memory address not used by the main kernel or BIOS using
2043 PHYSICAL_START, or it must be built as a relocatable image
2044 (CONFIG_RELOCATABLE=y).
2045 For more details see Documentation/admin-guide/kdump/kdump.rst
2049 depends on KEXEC && HIBERNATION
2051 Jump between original kernel and kexeced kernel and invoke
2052 code in physical address mode via KEXEC
2054 config PHYSICAL_START
2055 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2058 This gives the physical address where the kernel is loaded.
2060 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2061 bzImage will decompress itself to above physical address and
2062 run from there. Otherwise, bzImage will run from the address where
2063 it has been loaded by the boot loader and will ignore above physical
2066 In normal kdump cases one does not have to set/change this option
2067 as now bzImage can be compiled as a completely relocatable image
2068 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2069 address. This option is mainly useful for the folks who don't want
2070 to use a bzImage for capturing the crash dump and want to use a
2071 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2072 to be specifically compiled to run from a specific memory area
2073 (normally a reserved region) and this option comes handy.
2075 So if you are using bzImage for capturing the crash dump,
2076 leave the value here unchanged to 0x1000000 and set
2077 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2078 for capturing the crash dump change this value to start of
2079 the reserved region. In other words, it can be set based on
2080 the "X" value as specified in the "crashkernel=YM@XM"
2081 command line boot parameter passed to the panic-ed
2082 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2083 for more details about crash dumps.
2085 Usage of bzImage for capturing the crash dump is recommended as
2086 one does not have to build two kernels. Same kernel can be used
2087 as production kernel and capture kernel. Above option should have
2088 gone away after relocatable bzImage support is introduced. But it
2089 is present because there are users out there who continue to use
2090 vmlinux for dump capture. This option should go away down the
2093 Don't change this unless you know what you are doing.
2096 bool "Build a relocatable kernel"
2099 This builds a kernel image that retains relocation information
2100 so it can be loaded someplace besides the default 1MB.
2101 The relocations tend to make the kernel binary about 10% larger,
2102 but are discarded at runtime.
2104 One use is for the kexec on panic case where the recovery kernel
2105 must live at a different physical address than the primary
2108 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2109 it has been loaded at and the compile time physical address
2110 (CONFIG_PHYSICAL_START) is used as the minimum location.
2112 config RANDOMIZE_BASE
2113 bool "Randomize the address of the kernel image (KASLR)"
2114 depends on RELOCATABLE
2117 In support of Kernel Address Space Layout Randomization (KASLR),
2118 this randomizes the physical address at which the kernel image
2119 is decompressed and the virtual address where the kernel
2120 image is mapped, as a security feature that deters exploit
2121 attempts relying on knowledge of the location of kernel
2124 On 64-bit, the kernel physical and virtual addresses are
2125 randomized separately. The physical address will be anywhere
2126 between 16MB and the top of physical memory (up to 64TB). The
2127 virtual address will be randomized from 16MB up to 1GB (9 bits
2128 of entropy). Note that this also reduces the memory space
2129 available to kernel modules from 1.5GB to 1GB.
2131 On 32-bit, the kernel physical and virtual addresses are
2132 randomized together. They will be randomized from 16MB up to
2133 512MB (8 bits of entropy).
2135 Entropy is generated using the RDRAND instruction if it is
2136 supported. If RDTSC is supported, its value is mixed into
2137 the entropy pool as well. If neither RDRAND nor RDTSC are
2138 supported, then entropy is read from the i8254 timer. The
2139 usable entropy is limited by the kernel being built using
2140 2GB addressing, and that PHYSICAL_ALIGN must be at a
2141 minimum of 2MB. As a result, only 10 bits of entropy are
2142 theoretically possible, but the implementations are further
2143 limited due to memory layouts.
2147 # Relocation on x86 needs some additional build support
2148 config X86_NEED_RELOCS
2150 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2152 config PHYSICAL_ALIGN
2153 hex "Alignment value to which kernel should be aligned"
2155 range 0x2000 0x1000000 if X86_32
2156 range 0x200000 0x1000000 if X86_64
2158 This value puts the alignment restrictions on physical address
2159 where kernel is loaded and run from. Kernel is compiled for an
2160 address which meets above alignment restriction.
2162 If bootloader loads the kernel at a non-aligned address and
2163 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2164 address aligned to above value and run from there.
2166 If bootloader loads the kernel at a non-aligned address and
2167 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2168 load address and decompress itself to the address it has been
2169 compiled for and run from there. The address for which kernel is
2170 compiled already meets above alignment restrictions. Hence the
2171 end result is that kernel runs from a physical address meeting
2172 above alignment restrictions.
2174 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2175 this value must be a multiple of 0x200000.
2177 Don't change this unless you know what you are doing.
2179 config DYNAMIC_MEMORY_LAYOUT
2182 This option makes base addresses of vmalloc and vmemmap as well as
2183 __PAGE_OFFSET movable during boot.
2185 config RANDOMIZE_MEMORY
2186 bool "Randomize the kernel memory sections"
2188 depends on RANDOMIZE_BASE
2189 select DYNAMIC_MEMORY_LAYOUT
2190 default RANDOMIZE_BASE
2192 Randomizes the base virtual address of kernel memory sections
2193 (physical memory mapping, vmalloc & vmemmap). This security feature
2194 makes exploits relying on predictable memory locations less reliable.
2196 The order of allocations remains unchanged. Entropy is generated in
2197 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2198 configuration have in average 30,000 different possible virtual
2199 addresses for each memory section.
2203 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2204 hex "Physical memory mapping padding" if EXPERT
2205 depends on RANDOMIZE_MEMORY
2206 default "0xa" if MEMORY_HOTPLUG
2208 range 0x1 0x40 if MEMORY_HOTPLUG
2211 Define the padding in terabytes added to the existing physical
2212 memory size during kernel memory randomization. It is useful
2213 for memory hotplug support but reduces the entropy available for
2214 address randomization.
2216 If unsure, leave at the default value.
2222 config BOOTPARAM_HOTPLUG_CPU0
2223 bool "Set default setting of cpu0_hotpluggable"
2224 depends on HOTPLUG_CPU
2226 Set whether default state of cpu0_hotpluggable is on or off.
2228 Say Y here to enable CPU0 hotplug by default. If this switch
2229 is turned on, there is no need to give cpu0_hotplug kernel
2230 parameter and the CPU0 hotplug feature is enabled by default.
2232 Please note: there are two known CPU0 dependencies if you want
2233 to enable the CPU0 hotplug feature either by this switch or by
2234 cpu0_hotplug kernel parameter.
2236 First, resume from hibernate or suspend always starts from CPU0.
2237 So hibernate and suspend are prevented if CPU0 is offline.
2239 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2240 offline if any interrupt can not migrate out of CPU0. There may
2241 be other CPU0 dependencies.
2243 Please make sure the dependencies are under your control before
2244 you enable this feature.
2246 Say N if you don't want to enable CPU0 hotplug feature by default.
2247 You still can enable the CPU0 hotplug feature at boot by kernel
2248 parameter cpu0_hotplug.
2250 config DEBUG_HOTPLUG_CPU0
2252 prompt "Debug CPU0 hotplug"
2253 depends on HOTPLUG_CPU
2255 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2256 soon as possible and boots up userspace with CPU0 offlined. User
2257 can online CPU0 back after boot time.
2259 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2260 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2261 compilation or giving cpu0_hotplug kernel parameter at boot.
2267 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2268 depends on COMPAT_32
2270 Certain buggy versions of glibc will crash if they are
2271 presented with a 32-bit vDSO that is not mapped at the address
2272 indicated in its segment table.
2274 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2275 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2276 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2277 the only released version with the bug, but OpenSUSE 9
2278 contains a buggy "glibc 2.3.2".
2280 The symptom of the bug is that everything crashes on startup, saying:
2281 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2283 Saying Y here changes the default value of the vdso32 boot
2284 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2285 This works around the glibc bug but hurts performance.
2287 If unsure, say N: if you are compiling your own kernel, you
2288 are unlikely to be using a buggy version of glibc.
2291 prompt "vsyscall table for legacy applications"
2293 default LEGACY_VSYSCALL_XONLY
2295 Legacy user code that does not know how to find the vDSO expects
2296 to be able to issue three syscalls by calling fixed addresses in
2297 kernel space. Since this location is not randomized with ASLR,
2298 it can be used to assist security vulnerability exploitation.
2300 This setting can be changed at boot time via the kernel command
2301 line parameter vsyscall=[emulate|xonly|none].
2303 On a system with recent enough glibc (2.14 or newer) and no
2304 static binaries, you can say None without a performance penalty
2305 to improve security.
2307 If unsure, select "Emulate execution only".
2309 config LEGACY_VSYSCALL_EMULATE
2310 bool "Full emulation"
2312 The kernel traps and emulates calls into the fixed vsyscall
2313 address mapping. This makes the mapping non-executable, but
2314 it still contains readable known contents, which could be
2315 used in certain rare security vulnerability exploits. This
2316 configuration is recommended when using legacy userspace
2317 that still uses vsyscalls along with legacy binary
2318 instrumentation tools that require code to be readable.
2320 An example of this type of legacy userspace is running
2321 Pin on an old binary that still uses vsyscalls.
2323 config LEGACY_VSYSCALL_XONLY
2324 bool "Emulate execution only"
2326 The kernel traps and emulates calls into the fixed vsyscall
2327 address mapping and does not allow reads. This
2328 configuration is recommended when userspace might use the
2329 legacy vsyscall area but support for legacy binary
2330 instrumentation of legacy code is not needed. It mitigates
2331 certain uses of the vsyscall area as an ASLR-bypassing
2334 config LEGACY_VSYSCALL_NONE
2337 There will be no vsyscall mapping at all. This will
2338 eliminate any risk of ASLR bypass due to the vsyscall
2339 fixed address mapping. Attempts to use the vsyscalls
2340 will be reported to dmesg, so that either old or
2341 malicious userspace programs can be identified.
2346 bool "Built-in kernel command line"
2348 Allow for specifying boot arguments to the kernel at
2349 build time. On some systems (e.g. embedded ones), it is
2350 necessary or convenient to provide some or all of the
2351 kernel boot arguments with the kernel itself (that is,
2352 to not rely on the boot loader to provide them.)
2354 To compile command line arguments into the kernel,
2355 set this option to 'Y', then fill in the
2356 boot arguments in CONFIG_CMDLINE.
2358 Systems with fully functional boot loaders (i.e. non-embedded)
2359 should leave this option set to 'N'.
2362 string "Built-in kernel command string"
2363 depends on CMDLINE_BOOL
2366 Enter arguments here that should be compiled into the kernel
2367 image and used at boot time. If the boot loader provides a
2368 command line at boot time, it is appended to this string to
2369 form the full kernel command line, when the system boots.
2371 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2372 change this behavior.
2374 In most cases, the command line (whether built-in or provided
2375 by the boot loader) should specify the device for the root
2378 config CMDLINE_OVERRIDE
2379 bool "Built-in command line overrides boot loader arguments"
2380 depends on CMDLINE_BOOL && CMDLINE != ""
2382 Set this option to 'Y' to have the kernel ignore the boot loader
2383 command line, and use ONLY the built-in command line.
2385 This is used to work around broken boot loaders. This should
2386 be set to 'N' under normal conditions.
2388 config MODIFY_LDT_SYSCALL
2389 bool "Enable the LDT (local descriptor table)" if EXPERT
2392 Linux can allow user programs to install a per-process x86
2393 Local Descriptor Table (LDT) using the modify_ldt(2) system
2394 call. This is required to run 16-bit or segmented code such as
2395 DOSEMU or some Wine programs. It is also used by some very old
2396 threading libraries.
2398 Enabling this feature adds a small amount of overhead to
2399 context switches and increases the low-level kernel attack
2400 surface. Disabling it removes the modify_ldt(2) system call.
2402 Saying 'N' here may make sense for embedded or server kernels.
2404 config STRICT_SIGALTSTACK_SIZE
2405 bool "Enforce strict size checking for sigaltstack"
2406 depends on DYNAMIC_SIGFRAME
2408 For historical reasons MINSIGSTKSZ is a constant which became
2409 already too small with AVX512 support. Add a mechanism to
2410 enforce strict checking of the sigaltstack size against the
2411 real size of the FPU frame. This option enables the check
2412 by default. It can also be controlled via the kernel command
2413 line option 'strict_sas_size' independent of this config
2414 switch. Enabling it might break existing applications which
2415 allocate a too small sigaltstack but 'work' because they
2416 never get a signal delivered.
2418 Say 'N' unless you want to really enforce this check.
2420 source "kernel/livepatch/Kconfig"
2424 config ARCH_HAS_ADD_PAGES
2426 depends on ARCH_ENABLE_MEMORY_HOTPLUG
2428 config ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
2431 config USE_PERCPU_NUMA_NODE_ID
2435 menu "Power management and ACPI options"
2437 config ARCH_HIBERNATION_HEADER
2439 depends on HIBERNATION
2441 source "kernel/power/Kconfig"
2443 source "drivers/acpi/Kconfig"
2450 tristate "APM (Advanced Power Management) BIOS support"
2451 depends on X86_32 && PM_SLEEP
2453 APM is a BIOS specification for saving power using several different
2454 techniques. This is mostly useful for battery powered laptops with
2455 APM compliant BIOSes. If you say Y here, the system time will be
2456 reset after a RESUME operation, the /proc/apm device will provide
2457 battery status information, and user-space programs will receive
2458 notification of APM "events" (e.g. battery status change).
2460 If you select "Y" here, you can disable actual use of the APM
2461 BIOS by passing the "apm=off" option to the kernel at boot time.
2463 Note that the APM support is almost completely disabled for
2464 machines with more than one CPU.
2466 In order to use APM, you will need supporting software. For location
2467 and more information, read <file:Documentation/power/apm-acpi.rst>
2468 and the Battery Powered Linux mini-HOWTO, available from
2469 <http://www.tldp.org/docs.html#howto>.
2471 This driver does not spin down disk drives (see the hdparm(8)
2472 manpage ("man 8 hdparm") for that), and it doesn't turn off
2473 VESA-compliant "green" monitors.
2475 This driver does not support the TI 4000M TravelMate and the ACER
2476 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2477 desktop machines also don't have compliant BIOSes, and this driver
2478 may cause those machines to panic during the boot phase.
2480 Generally, if you don't have a battery in your machine, there isn't
2481 much point in using this driver and you should say N. If you get
2482 random kernel OOPSes or reboots that don't seem to be related to
2483 anything, try disabling/enabling this option (or disabling/enabling
2486 Some other things you should try when experiencing seemingly random,
2489 1) make sure that you have enough swap space and that it is
2491 2) pass the "no-hlt" option to the kernel
2492 3) switch on floating point emulation in the kernel and pass
2493 the "no387" option to the kernel
2494 4) pass the "floppy=nodma" option to the kernel
2495 5) pass the "mem=4M" option to the kernel (thereby disabling
2496 all but the first 4 MB of RAM)
2497 6) make sure that the CPU is not over clocked.
2498 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2499 8) disable the cache from your BIOS settings
2500 9) install a fan for the video card or exchange video RAM
2501 10) install a better fan for the CPU
2502 11) exchange RAM chips
2503 12) exchange the motherboard.
2505 To compile this driver as a module, choose M here: the
2506 module will be called apm.
2510 config APM_IGNORE_USER_SUSPEND
2511 bool "Ignore USER SUSPEND"
2513 This option will ignore USER SUSPEND requests. On machines with a
2514 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2515 series notebooks, it is necessary to say Y because of a BIOS bug.
2517 config APM_DO_ENABLE
2518 bool "Enable PM at boot time"
2520 Enable APM features at boot time. From page 36 of the APM BIOS
2521 specification: "When disabled, the APM BIOS does not automatically
2522 power manage devices, enter the Standby State, enter the Suspend
2523 State, or take power saving steps in response to CPU Idle calls."
2524 This driver will make CPU Idle calls when Linux is idle (unless this
2525 feature is turned off -- see "Do CPU IDLE calls", below). This
2526 should always save battery power, but more complicated APM features
2527 will be dependent on your BIOS implementation. You may need to turn
2528 this option off if your computer hangs at boot time when using APM
2529 support, or if it beeps continuously instead of suspending. Turn
2530 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2531 T400CDT. This is off by default since most machines do fine without
2536 bool "Make CPU Idle calls when idle"
2538 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2539 On some machines, this can activate improved power savings, such as
2540 a slowed CPU clock rate, when the machine is idle. These idle calls
2541 are made after the idle loop has run for some length of time (e.g.,
2542 333 mS). On some machines, this will cause a hang at boot time or
2543 whenever the CPU becomes idle. (On machines with more than one CPU,
2544 this option does nothing.)
2546 config APM_DISPLAY_BLANK
2547 bool "Enable console blanking using APM"
2549 Enable console blanking using the APM. Some laptops can use this to
2550 turn off the LCD backlight when the screen blanker of the Linux
2551 virtual console blanks the screen. Note that this is only used by
2552 the virtual console screen blanker, and won't turn off the backlight
2553 when using the X Window system. This also doesn't have anything to
2554 do with your VESA-compliant power-saving monitor. Further, this
2555 option doesn't work for all laptops -- it might not turn off your
2556 backlight at all, or it might print a lot of errors to the console,
2557 especially if you are using gpm.
2559 config APM_ALLOW_INTS
2560 bool "Allow interrupts during APM BIOS calls"
2562 Normally we disable external interrupts while we are making calls to
2563 the APM BIOS as a measure to lessen the effects of a badly behaving
2564 BIOS implementation. The BIOS should reenable interrupts if it
2565 needs to. Unfortunately, some BIOSes do not -- especially those in
2566 many of the newer IBM Thinkpads. If you experience hangs when you
2567 suspend, try setting this to Y. Otherwise, say N.
2571 source "drivers/cpufreq/Kconfig"
2573 source "drivers/cpuidle/Kconfig"
2575 source "drivers/idle/Kconfig"
2580 menu "Bus options (PCI etc.)"
2583 prompt "PCI access mode"
2584 depends on X86_32 && PCI
2587 On PCI systems, the BIOS can be used to detect the PCI devices and
2588 determine their configuration. However, some old PCI motherboards
2589 have BIOS bugs and may crash if this is done. Also, some embedded
2590 PCI-based systems don't have any BIOS at all. Linux can also try to
2591 detect the PCI hardware directly without using the BIOS.
2593 With this option, you can specify how Linux should detect the
2594 PCI devices. If you choose "BIOS", the BIOS will be used,
2595 if you choose "Direct", the BIOS won't be used, and if you
2596 choose "MMConfig", then PCI Express MMCONFIG will be used.
2597 If you choose "Any", the kernel will try MMCONFIG, then the
2598 direct access method and falls back to the BIOS if that doesn't
2599 work. If unsure, go with the default, which is "Any".
2604 config PCI_GOMMCONFIG
2621 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2623 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2626 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2629 bool "Support mmconfig PCI config space access" if X86_64
2631 depends on PCI && (ACPI || JAILHOUSE_GUEST)
2632 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2636 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2640 depends on PCI && XEN
2642 config MMCONF_FAM10H
2644 depends on X86_64 && PCI_MMCONFIG && ACPI
2646 config PCI_CNB20LE_QUIRK
2647 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2650 Read the PCI windows out of the CNB20LE host bridge. This allows
2651 PCI hotplug to work on systems with the CNB20LE chipset which do
2654 There's no public spec for this chipset, and this functionality
2655 is known to be incomplete.
2657 You should say N unless you know you need this.
2660 bool "ISA bus support on modern systems" if EXPERT
2662 Expose ISA bus device drivers and options available for selection and
2663 configuration. Enable this option if your target machine has an ISA
2664 bus. ISA is an older system, displaced by PCI and newer bus
2665 architectures -- if your target machine is modern, it probably does
2666 not have an ISA bus.
2670 # x86_64 have no ISA slots, but can have ISA-style DMA.
2672 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2675 Enables ISA-style DMA support for devices requiring such controllers.
2683 Find out whether you have ISA slots on your motherboard. ISA is the
2684 name of a bus system, i.e. the way the CPU talks to the other stuff
2685 inside your box. Other bus systems are PCI, EISA, MicroChannel
2686 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2687 newer boards don't support it. If you have ISA, say Y, otherwise N.
2690 tristate "NatSemi SCx200 support"
2692 This provides basic support for National Semiconductor's
2693 (now AMD's) Geode processors. The driver probes for the
2694 PCI-IDs of several on-chip devices, so its a good dependency
2695 for other scx200_* drivers.
2697 If compiled as a module, the driver is named scx200.
2699 config SCx200HR_TIMER
2700 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2704 This driver provides a clocksource built upon the on-chip
2705 27MHz high-resolution timer. Its also a workaround for
2706 NSC Geode SC-1100's buggy TSC, which loses time when the
2707 processor goes idle (as is done by the scheduler). The
2708 other workaround is idle=poll boot option.
2711 bool "One Laptop Per Child support"
2719 Add support for detecting the unique features of the OLPC
2723 bool "OLPC XO-1 Power Management"
2724 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2726 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2729 bool "OLPC XO-1 Real Time Clock"
2730 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2732 Add support for the XO-1 real time clock, which can be used as a
2733 programmable wakeup source.
2736 bool "OLPC XO-1 SCI extras"
2737 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2741 Add support for SCI-based features of the OLPC XO-1 laptop:
2742 - EC-driven system wakeups
2746 - AC adapter status updates
2747 - Battery status updates
2749 config OLPC_XO15_SCI
2750 bool "OLPC XO-1.5 SCI extras"
2751 depends on OLPC && ACPI
2754 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2755 - EC-driven system wakeups
2756 - AC adapter status updates
2757 - Battery status updates
2760 bool "PCEngines ALIX System Support (LED setup)"
2763 This option enables system support for the PCEngines ALIX.
2764 At present this just sets up LEDs for GPIO control on
2765 ALIX2/3/6 boards. However, other system specific setup should
2768 Note: You must still enable the drivers for GPIO and LED support
2769 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2771 Note: You have to set alix.force=1 for boards with Award BIOS.
2774 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2777 This option enables system support for the Soekris Engineering net5501.
2780 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2784 This option enables system support for the Traverse Technologies GEOS.
2787 bool "Technologic Systems TS-5500 platform support"
2789 select CHECK_SIGNATURE
2793 This option enables system support for the Technologic Systems TS-5500.
2799 depends on CPU_SUP_AMD && PCI
2804 menu "Binary Emulations"
2806 config IA32_EMULATION
2807 bool "IA32 Emulation"
2809 select ARCH_WANT_OLD_COMPAT_IPC
2811 select COMPAT_OLD_SIGACTION
2813 Include code to run legacy 32-bit programs under a
2814 64-bit kernel. You should likely turn this on, unless you're
2815 100% sure that you don't have any 32-bit programs left.
2818 tristate "IA32 a.out support"
2819 depends on IA32_EMULATION
2822 Support old a.out binaries in the 32bit emulation.
2825 bool "x32 ABI for 64-bit mode"
2828 Include code to run binaries for the x32 native 32-bit ABI
2829 for 64-bit processors. An x32 process gets access to the
2830 full 64-bit register file and wide data path while leaving
2831 pointers at 32 bits for smaller memory footprint.
2833 You will need a recent binutils (2.22 or later) with
2834 elf32_x86_64 support enabled to compile a kernel with this
2839 depends on IA32_EMULATION || X86_32
2841 select OLD_SIGSUSPEND3
2845 depends on IA32_EMULATION || X86_X32
2848 config COMPAT_FOR_U64_ALIGNMENT
2851 config SYSVIPC_COMPAT
2859 config HAVE_ATOMIC_IOMAP
2863 source "arch/x86/kvm/Kconfig"
2865 source "arch/x86/Kconfig.assembler"