1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select HAVE_DEBUG_STACKOVERFLOW
18 select MODULES_USE_ELF_REL
20 select GENERIC_VDSO_32
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE
27 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select NEED_DMA_MAP_STATE
34 config FORCE_DYNAMIC_FTRACE
37 depends on FUNCTION_TRACER
40 We keep the static function tracing (!DYNAMIC_FTRACE) around
41 in order to test the non static function tracing in the
42 generic code, as other architectures still use it. But we
43 only need to keep it around for x86_64. No need to keep it
44 for x86_32. For x86_32, force DYNAMIC_FTRACE.
48 # ( Note that options that are marked 'if X86_64' could in principle be
49 # ported to 32-bit as well. )
54 # Note: keep this list sorted alphabetically
56 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
57 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
58 select ARCH_32BIT_OFF_T if X86_32
59 select ARCH_CLOCKSOURCE_INIT
60 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
61 select ARCH_HAS_DEBUG_VIRTUAL
62 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
63 select ARCH_HAS_DEVMEM_IS_ALLOWED
64 select ARCH_HAS_EARLY_DEBUG if KGDB
65 select ARCH_HAS_ELF_RANDOMIZE
66 select ARCH_HAS_FAST_MULTIPLIER
67 select ARCH_HAS_FILTER_PGPROT
68 select ARCH_HAS_FORTIFY_SOURCE
69 select ARCH_HAS_GCOV_PROFILE_ALL
70 select ARCH_HAS_KCOV if X86_64
71 select ARCH_HAS_MEM_ENCRYPT
72 select ARCH_HAS_MEMBARRIER_SYNC_CORE
73 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
74 select ARCH_HAS_PMEM_API if X86_64
75 select ARCH_HAS_PTE_DEVMAP if X86_64
76 select ARCH_HAS_PTE_SPECIAL
77 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
78 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
79 select ARCH_HAS_SET_MEMORY
80 select ARCH_HAS_SET_DIRECT_MAP
81 select ARCH_HAS_STRICT_KERNEL_RWX
82 select ARCH_HAS_STRICT_MODULE_RWX
83 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
84 select ARCH_HAS_SYSCALL_WRAPPER
85 select ARCH_HAS_UBSAN_SANITIZE_ALL
86 select ARCH_HAS_DEBUG_WX
87 select ARCH_HAVE_NMI_SAFE_CMPXCHG
88 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
89 select ARCH_MIGHT_HAVE_PC_PARPORT
90 select ARCH_MIGHT_HAVE_PC_SERIO
92 select ARCH_SUPPORTS_ACPI
93 select ARCH_SUPPORTS_ATOMIC_RMW
94 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
95 select ARCH_USE_BUILTIN_BSWAP
96 select ARCH_USE_QUEUED_RWLOCKS
97 select ARCH_USE_QUEUED_SPINLOCKS
98 select ARCH_USE_SYM_ANNOTATIONS
99 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
100 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
101 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
102 select ARCH_WANT_HUGE_PMD_SHARE
103 select ARCH_WANTS_THP_SWAP if X86_64
104 select BUILDTIME_TABLE_SORT
106 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
107 select CLOCKSOURCE_WATCHDOG
108 select DCACHE_WORD_ACCESS
109 select EDAC_ATOMIC_SCRUB
111 select GENERIC_CLOCKEVENTS
112 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
113 select GENERIC_CLOCKEVENTS_MIN_ADJUST
114 select GENERIC_CMOS_UPDATE
115 select GENERIC_CPU_AUTOPROBE
116 select GENERIC_CPU_VULNERABILITIES
117 select GENERIC_EARLY_IOREMAP
118 select GENERIC_FIND_FIRST_BIT
120 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
121 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
122 select GENERIC_IRQ_MIGRATION if SMP
123 select GENERIC_IRQ_PROBE
124 select GENERIC_IRQ_RESERVATION_MODE
125 select GENERIC_IRQ_SHOW
126 select GENERIC_PENDING_IRQ if SMP
127 select GENERIC_PTDUMP
128 select GENERIC_SMP_IDLE_THREAD
129 select GENERIC_STRNCPY_FROM_USER
130 select GENERIC_STRNLEN_USER
131 select GENERIC_TIME_VSYSCALL
132 select GENERIC_GETTIMEOFDAY
133 select GENERIC_VDSO_TIME_NS
134 select GUP_GET_PTE_LOW_HIGH if X86_PAE
135 select HARDIRQS_SW_RESEND
136 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
137 select HAVE_ACPI_APEI if ACPI
138 select HAVE_ACPI_APEI_NMI if ACPI
139 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
140 select HAVE_ARCH_AUDITSYSCALL
141 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
142 select HAVE_ARCH_JUMP_LABEL
143 select HAVE_ARCH_JUMP_LABEL_RELATIVE
144 select HAVE_ARCH_KASAN if X86_64
145 select HAVE_ARCH_KASAN_VMALLOC if X86_64
146 select HAVE_ARCH_KGDB
147 select HAVE_ARCH_MMAP_RND_BITS if MMU
148 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
149 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
150 select HAVE_ARCH_PREL32_RELOCATIONS
151 select HAVE_ARCH_SECCOMP_FILTER
152 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
153 select HAVE_ARCH_STACKLEAK
154 select HAVE_ARCH_TRACEHOOK
155 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
156 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
157 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
158 select HAVE_ARCH_VMAP_STACK if X86_64
159 select HAVE_ARCH_WITHIN_STACK_FRAMES
160 select HAVE_ASM_MODVERSIONS
161 select HAVE_CMPXCHG_DOUBLE
162 select HAVE_CMPXCHG_LOCAL
163 select HAVE_CONTEXT_TRACKING if X86_64
164 select HAVE_COPY_THREAD_TLS
165 select HAVE_C_RECORDMCOUNT
166 select HAVE_DEBUG_KMEMLEAK
167 select HAVE_DMA_CONTIGUOUS
168 select HAVE_DYNAMIC_FTRACE
169 select HAVE_DYNAMIC_FTRACE_WITH_REGS
170 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
172 select HAVE_EFFICIENT_UNALIGNED_ACCESS
174 select HAVE_EXIT_THREAD
176 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
177 select HAVE_FTRACE_MCOUNT_RECORD
178 select HAVE_FUNCTION_GRAPH_TRACER
179 select HAVE_FUNCTION_TRACER
180 select HAVE_GCC_PLUGINS
181 select HAVE_HW_BREAKPOINT
183 select HAVE_IOREMAP_PROT
184 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
185 select HAVE_IRQ_TIME_ACCOUNTING
186 select HAVE_KERNEL_BZIP2
187 select HAVE_KERNEL_GZIP
188 select HAVE_KERNEL_LZ4
189 select HAVE_KERNEL_LZMA
190 select HAVE_KERNEL_LZO
191 select HAVE_KERNEL_XZ
193 select HAVE_KPROBES_ON_FTRACE
194 select HAVE_FUNCTION_ERROR_INJECTION
195 select HAVE_KRETPROBES
197 select HAVE_LIVEPATCH if X86_64
198 select HAVE_MIXED_BREAKPOINTS_REGS
199 select HAVE_MOD_ARCH_SPECIFIC
203 select HAVE_OPTPROBES
204 select HAVE_PCSPKR_PLATFORM
205 select HAVE_PERF_EVENTS
206 select HAVE_PERF_EVENTS_NMI
207 select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
209 select HAVE_PERF_REGS
210 select HAVE_PERF_USER_STACK_DUMP
211 select MMU_GATHER_RCU_TABLE_FREE if PARAVIRT
212 select HAVE_REGS_AND_STACK_ACCESS_API
213 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
214 select HAVE_FUNCTION_ARG_ACCESS_API
215 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
216 select HAVE_STACK_VALIDATION if X86_64
218 select HAVE_SYSCALL_TRACEPOINTS
219 select HAVE_UNSTABLE_SCHED_CLOCK
220 select HAVE_USER_RETURN_NOTIFIER
221 select HAVE_GENERIC_VDSO
222 select HOTPLUG_SMT if SMP
223 select IRQ_FORCED_THREADING
224 select NEED_SG_DMA_LENGTH
225 select PCI_DOMAINS if PCI
226 select PCI_LOCKLESS_CONFIG if PCI
229 select RTC_MC146818_LIB
232 select SYSCTL_EXCEPTION_TRACE
233 select THREAD_INFO_IN_TASK
234 select USER_STACKTRACE_SUPPORT
236 select X86_FEATURE_NAMES if PROC_FS
237 select PROC_PID_ARCH_STATUS if PROC_FS
238 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
240 config INSTRUCTION_DECODER
242 depends on KPROBES || PERF_EVENTS || UPROBES
246 default "elf32-i386" if X86_32
247 default "elf64-x86-64" if X86_64
249 config LOCKDEP_SUPPORT
252 config STACKTRACE_SUPPORT
258 config ARCH_MMAP_RND_BITS_MIN
262 config ARCH_MMAP_RND_BITS_MAX
266 config ARCH_MMAP_RND_COMPAT_BITS_MIN
269 config ARCH_MMAP_RND_COMPAT_BITS_MAX
275 config GENERIC_ISA_DMA
277 depends on ISA_DMA_API
282 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
284 config GENERIC_BUG_RELATIVE_POINTERS
287 config ARCH_MAY_HAVE_PC_FDC
289 depends on ISA_DMA_API
291 config GENERIC_CALIBRATE_DELAY
294 config ARCH_HAS_CPU_RELAX
297 config ARCH_HAS_CACHE_LINE_SIZE
300 config ARCH_HAS_FILTER_PGPROT
303 config HAVE_SETUP_PER_CPU_AREA
306 config NEED_PER_CPU_EMBED_FIRST_CHUNK
309 config NEED_PER_CPU_PAGE_FIRST_CHUNK
312 config ARCH_HIBERNATION_POSSIBLE
315 config ARCH_SUSPEND_POSSIBLE
318 config ARCH_WANT_GENERAL_HUGETLB
327 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
330 config KASAN_SHADOW_OFFSET
333 default 0xdffffc0000000000
335 config HAVE_INTEL_TXT
337 depends on INTEL_IOMMU && ACPI
341 depends on X86_32 && SMP
345 depends on X86_64 && SMP
347 config X86_32_LAZY_GS
349 depends on X86_32 && !STACKPROTECTOR
351 config ARCH_SUPPORTS_UPROBES
354 config FIX_EARLYCON_MEM
357 config DYNAMIC_PHYSICAL_MASK
360 config PGTABLE_LEVELS
362 default 5 if X86_5LEVEL
367 config CC_HAS_SANE_STACKPROTECTOR
369 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
370 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
372 We have to make sure stack protector is unconditionally disabled if
373 the compiler produces broken code.
375 menu "Processor type and features"
378 bool "DMA memory allocation support" if EXPERT
381 DMA memory allocation support allows devices with less than 32-bit
382 addressing to allocate within the first 16MB of address space.
383 Disable if no such devices will be used.
388 bool "Symmetric multi-processing support"
390 This enables support for systems with more than one CPU. If you have
391 a system with only one CPU, say N. If you have a system with more
394 If you say N here, the kernel will run on uni- and multiprocessor
395 machines, but will use only one CPU of a multiprocessor machine. If
396 you say Y here, the kernel will run on many, but not all,
397 uniprocessor machines. On a uniprocessor machine, the kernel
398 will run faster if you say N here.
400 Note that if you say Y here and choose architecture "586" or
401 "Pentium" under "Processor family", the kernel will not work on 486
402 architectures. Similarly, multiprocessor kernels for the "PPro"
403 architecture may not work on all Pentium based boards.
405 People using multiprocessor machines who say Y here should also say
406 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
407 Management" code will be disabled if you say Y here.
409 See also <file:Documentation/x86/i386/IO-APIC.rst>,
410 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
411 <http://www.tldp.org/docs.html#howto>.
413 If you don't know what to do here, say N.
415 config X86_FEATURE_NAMES
416 bool "Processor feature human-readable names" if EMBEDDED
419 This option compiles in a table of x86 feature bits and corresponding
420 names. This is required to support /proc/cpuinfo and a few kernel
421 messages. You can disable this to save space, at the expense of
422 making those few kernel messages show numeric feature bits instead.
427 bool "Support x2apic"
428 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
430 This enables x2apic support on CPUs that have this feature.
432 This allows 32-bit apic IDs (so it can support very large systems),
433 and accesses the local apic via MSRs not via mmio.
435 If you don't know what to do here, say N.
438 bool "Enable MPS table" if ACPI || SFI
440 depends on X86_LOCAL_APIC
442 For old smp systems that do not have proper acpi support. Newer systems
443 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
447 depends on X86_GOLDFISH
450 bool "Avoid speculative indirect branches in kernel"
452 select STACK_VALIDATION if HAVE_STACK_VALIDATION
454 Compile kernel with the retpoline compiler options to guard against
455 kernel-to-user data leaks by avoiding speculative indirect
456 branches. Requires a compiler with -mindirect-branch=thunk-extern
457 support for full protection. The kernel may run slower.
459 config X86_CPU_RESCTRL
460 bool "x86 CPU resource control support"
461 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
463 select PROC_CPU_RESCTRL if PROC_FS
465 Enable x86 CPU resource control support.
467 Provide support for the allocation and monitoring of system resources
470 Intel calls this Intel Resource Director Technology
471 (Intel(R) RDT). More information about RDT can be found in the
472 Intel x86 Architecture Software Developer Manual.
474 AMD calls this AMD Platform Quality of Service (AMD QoS).
475 More information about AMD QoS can be found in the AMD64 Technology
476 Platform Quality of Service Extensions manual.
482 bool "Support for big SMP systems with more than 8 CPUs"
485 This option is needed for the systems that have more than 8 CPUs.
487 config X86_EXTENDED_PLATFORM
488 bool "Support for extended (non-PC) x86 platforms"
491 If you disable this option then the kernel will only support
492 standard PC platforms. (which covers the vast majority of
495 If you enable this option then you'll be able to select support
496 for the following (non-PC) 32 bit x86 platforms:
497 Goldfish (Android emulator)
500 SGI 320/540 (Visual Workstation)
501 STA2X11-based (e.g. Northville)
502 Moorestown MID devices
504 If you have one of these systems, or if you want to build a
505 generic distribution kernel, say Y here - otherwise say N.
509 config X86_EXTENDED_PLATFORM
510 bool "Support for extended (non-PC) x86 platforms"
513 If you disable this option then the kernel will only support
514 standard PC platforms. (which covers the vast majority of
517 If you enable this option then you'll be able to select support
518 for the following (non-PC) 64 bit x86 platforms:
523 If you have one of these systems, or if you want to build a
524 generic distribution kernel, say Y here - otherwise say N.
526 # This is an alphabetically sorted list of 64 bit extended platforms
527 # Please maintain the alphabetic order if and when there are additions
529 bool "Numascale NumaChip"
531 depends on X86_EXTENDED_PLATFORM
534 depends on X86_X2APIC
535 depends on PCI_MMCONFIG
537 Adds support for Numascale NumaChip large-SMP systems. Needed to
538 enable more than ~168 cores.
539 If you don't have one of these, you should say N here.
543 select HYPERVISOR_GUEST
545 depends on X86_64 && PCI
546 depends on X86_EXTENDED_PLATFORM
549 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
550 supposed to run on these EM64T-based machines. Only choose this option
551 if you have one of these machines.
554 bool "SGI Ultraviolet"
556 depends on X86_EXTENDED_PLATFORM
559 depends on X86_X2APIC
562 This option is needed in order to support SGI Ultraviolet systems.
563 If you don't have one of these, you should say N here.
565 # Following is an alphabetically sorted list of 32 bit extended platforms
566 # Please maintain the alphabetic order if and when there are additions
569 bool "Goldfish (Virtual Platform)"
570 depends on X86_EXTENDED_PLATFORM
572 Enable support for the Goldfish virtual platform used primarily
573 for Android development. Unless you are building for the Android
574 Goldfish emulator say N here.
577 bool "CE4100 TV platform"
579 depends on PCI_GODIRECT
580 depends on X86_IO_APIC
582 depends on X86_EXTENDED_PLATFORM
583 select X86_REBOOTFIXUPS
585 select OF_EARLY_FLATTREE
587 Select for the Intel CE media processor (CE4100) SOC.
588 This option compiles in support for the CE4100 SOC for settop
589 boxes and media devices.
592 bool "Intel MID platform support"
593 depends on X86_EXTENDED_PLATFORM
594 depends on X86_PLATFORM_DEVICES
596 depends on X86_64 || (PCI_GOANY && X86_32)
597 depends on X86_IO_APIC
603 select MFD_INTEL_MSIC
605 Select to build a kernel capable of supporting Intel MID (Mobile
606 Internet Device) platform systems which do not have the PCI legacy
607 interfaces. If you are building for a PC class system say N here.
609 Intel MID platforms are based on an Intel processor and chipset which
610 consume less power than most of the x86 derivatives.
612 config X86_INTEL_QUARK
613 bool "Intel Quark platform support"
615 depends on X86_EXTENDED_PLATFORM
616 depends on X86_PLATFORM_DEVICES
620 depends on X86_IO_APIC
625 Select to include support for Quark X1000 SoC.
626 Say Y here if you have a Quark based system such as the Arduino
627 compatible Intel Galileo.
629 config X86_INTEL_LPSS
630 bool "Intel Low Power Subsystem Support"
631 depends on X86 && ACPI && PCI
636 Select to build support for Intel Low Power Subsystem such as
637 found on Intel Lynxpoint PCH. Selecting this option enables
638 things like clock tree (common clock framework) and pincontrol
639 which are needed by the LPSS peripheral drivers.
641 config X86_AMD_PLATFORM_DEVICE
642 bool "AMD ACPI2Platform devices support"
647 Select to interpret AMD specific ACPI device to platform device
648 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
649 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
650 implemented under PINCTRL subsystem.
653 tristate "Intel SoC IOSF Sideband support for SoC platforms"
656 This option enables sideband register access support for Intel SoC
657 platforms. On these platforms the IOSF sideband is used in lieu of
658 MSR's for some register accesses, mostly but not limited to thermal
659 and power. Drivers may query the availability of this device to
660 determine if they need the sideband in order to work on these
661 platforms. The sideband is available on the following SoC products.
662 This list is not meant to be exclusive.
667 You should say Y if you are running a kernel on one of these SoC's.
669 config IOSF_MBI_DEBUG
670 bool "Enable IOSF sideband access through debugfs"
671 depends on IOSF_MBI && DEBUG_FS
673 Select this option to expose the IOSF sideband access registers (MCR,
674 MDR, MCRX) through debugfs to write and read register information from
675 different units on the SoC. This is most useful for obtaining device
676 state information for debug and analysis. As this is a general access
677 mechanism, users of this option would have specific knowledge of the
678 device they want to access.
680 If you don't require the option or are in doubt, say N.
683 bool "RDC R-321x SoC"
685 depends on X86_EXTENDED_PLATFORM
687 select X86_REBOOTFIXUPS
689 This option is needed for RDC R-321x system-on-chip, also known
691 If you don't have one of these chips, you should say N here.
693 config X86_32_NON_STANDARD
694 bool "Support non-standard 32-bit SMP architectures"
695 depends on X86_32 && SMP
696 depends on X86_EXTENDED_PLATFORM
698 This option compiles in the bigsmp and STA2X11 default
699 subarchitectures. It is intended for a generic binary
700 kernel. If you select them all, kernel will probe it one by
701 one and will fallback to default.
703 # Alphabetically sorted list of Non standard 32 bit platforms
705 config X86_SUPPORTS_MEMORY_FAILURE
707 # MCE code calls memory_failure():
709 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
710 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
711 depends on X86_64 || !SPARSEMEM
712 select ARCH_SUPPORTS_MEMORY_FAILURE
715 bool "STA2X11 Companion Chip Support"
716 depends on X86_32_NON_STANDARD && PCI
721 This adds support for boards based on the STA2X11 IO-Hub,
722 a.k.a. "ConneXt". The chip is used in place of the standard
723 PC chipset, so all "standard" peripherals are missing. If this
724 option is selected the kernel will still be able to boot on
725 standard PC machines.
728 tristate "Eurobraille/Iris poweroff module"
731 The Iris machines from EuroBraille do not have APM or ACPI support
732 to shut themselves down properly. A special I/O sequence is
733 needed to do so, which is what this module does at
736 This is only for Iris machines from EuroBraille.
740 config SCHED_OMIT_FRAME_POINTER
742 prompt "Single-depth WCHAN output"
745 Calculate simpler /proc/<PID>/wchan values. If this option
746 is disabled then wchan values will recurse back to the
747 caller function. This provides more accurate wchan values,
748 at the expense of slightly more scheduling overhead.
750 If in doubt, say "Y".
752 menuconfig HYPERVISOR_GUEST
753 bool "Linux guest support"
755 Say Y here to enable options for running Linux under various hyper-
756 visors. This option enables basic hypervisor detection and platform
759 If you say N, all options in this submenu will be skipped and
760 disabled, and Linux guest support won't be built in.
765 bool "Enable paravirtualization code"
767 This changes the kernel so it can modify itself when it is run
768 under a hypervisor, potentially improving performance significantly
769 over full virtualization. However, when run without a hypervisor
770 the kernel is theoretically slower and slightly larger.
775 config PARAVIRT_DEBUG
776 bool "paravirt-ops debugging"
777 depends on PARAVIRT && DEBUG_KERNEL
779 Enable to debug paravirt_ops internals. Specifically, BUG if
780 a paravirt_op is missing when it is called.
782 config PARAVIRT_SPINLOCKS
783 bool "Paravirtualization layer for spinlocks"
784 depends on PARAVIRT && SMP
786 Paravirtualized spinlocks allow a pvops backend to replace the
787 spinlock implementation with something virtualization-friendly
788 (for example, block the virtual CPU rather than spinning).
790 It has a minimal impact on native kernels and gives a nice performance
791 benefit on paravirtualized KVM / Xen kernels.
793 If you are unsure how to answer this question, answer Y.
795 config X86_HV_CALLBACK_VECTOR
798 source "arch/x86/xen/Kconfig"
801 bool "KVM Guest support (including kvmclock)"
803 select PARAVIRT_CLOCK
804 select ARCH_CPUIDLE_HALTPOLL
807 This option enables various optimizations for running under the KVM
808 hypervisor. It includes a paravirtualized clock, so that instead
809 of relying on a PIT (or probably other) emulation by the
810 underlying device model, the host provides the guest with
811 timing infrastructure such as time of day, and system time
813 config ARCH_CPUIDLE_HALTPOLL
815 prompt "Disable host haltpoll when loading haltpoll driver"
817 If virtualized under KVM, disable host haltpoll.
820 bool "Support for running PVH guests"
822 This option enables the PVH entry point for guest virtual machines
823 as specified in the x86/HVM direct boot ABI.
826 bool "Enable debug information for KVM Guests in debugfs"
827 depends on KVM_GUEST && DEBUG_FS
829 This option enables collection of various statistics for KVM guest.
830 Statistics are displayed in debugfs filesystem. Enabling this option
831 may incur significant overhead.
833 config PARAVIRT_TIME_ACCOUNTING
834 bool "Paravirtual steal time accounting"
837 Select this option to enable fine granularity task steal time
838 accounting. Time spent executing other tasks in parallel with
839 the current vCPU is discounted from the vCPU power. To account for
840 that, there can be a small performance impact.
842 If in doubt, say N here.
844 config PARAVIRT_CLOCK
847 config JAILHOUSE_GUEST
848 bool "Jailhouse non-root cell support"
849 depends on X86_64 && PCI
852 This option allows to run Linux as guest in a Jailhouse non-root
853 cell. You can leave this option disabled if you only want to start
854 Jailhouse and run Linux afterwards in the root cell.
857 bool "ACRN Guest support"
859 select X86_HV_CALLBACK_VECTOR
861 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
862 a flexible, lightweight reference open-source hypervisor, built with
863 real-time and safety-criticality in mind. It is built for embedded
864 IOT with small footprint and real-time features. More details can be
865 found in https://projectacrn.org/.
867 endif #HYPERVISOR_GUEST
869 source "arch/x86/Kconfig.cpu"
873 prompt "HPET Timer Support" if X86_32
875 Use the IA-PC HPET (High Precision Event Timer) to manage
876 time in preference to the PIT and RTC, if a HPET is
878 HPET is the next generation timer replacing legacy 8254s.
879 The HPET provides a stable time base on SMP
880 systems, unlike the TSC, but it is more expensive to access,
881 as it is off-chip. The interface used is documented
882 in the HPET spec, revision 1.
884 You can safely choose Y here. However, HPET will only be
885 activated if the platform and the BIOS support this feature.
886 Otherwise the 8254 will be used for timing services.
888 Choose N to continue using the legacy 8254 timer.
890 config HPET_EMULATE_RTC
892 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
895 def_bool y if X86_INTEL_MID
896 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
898 depends on X86_INTEL_MID && SFI
900 APB timer is the replacement for 8254, HPET on X86 MID platforms.
901 The APBT provides a stable time base on SMP
902 systems, unlike the TSC, but it is more expensive to access,
903 as it is off-chip. APB timers are always running regardless of CPU
904 C states, they are used as per CPU clockevent device when possible.
906 # Mark as expert because too many people got it wrong.
907 # The code disables itself when not needed.
910 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
911 bool "Enable DMI scanning" if EXPERT
913 Enabled scanning of DMI to identify machine quirks. Say Y
914 here unless you have verified that your setup is not
915 affected by entries in the DMI blacklist. Required by PNP
919 bool "Old AMD GART IOMMU support"
922 depends on X86_64 && PCI && AMD_NB
924 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
925 GART based hardware IOMMUs.
927 The GART supports full DMA access for devices with 32-bit access
928 limitations, on systems with more than 3 GB. This is usually needed
929 for USB, sound, many IDE/SATA chipsets and some other devices.
931 Newer systems typically have a modern AMD IOMMU, supported via
932 the CONFIG_AMD_IOMMU=y config option.
934 In normal configurations this driver is only active when needed:
935 there's more than 3 GB of memory and the system contains a
936 32-bit limited device.
941 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
942 depends on X86_64 && SMP && DEBUG_KERNEL
943 select CPUMASK_OFFSTACK
945 Enable maximum number of CPUS and NUMA Nodes for this architecture.
949 # The maximum number of CPUs supported:
951 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
952 # and which can be configured interactively in the
953 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
955 # The ranges are different on 32-bit and 64-bit kernels, depending on
956 # hardware capabilities and scalability features of the kernel.
958 # ( If MAXSMP is enabled we just use the highest possible value and disable
959 # interactive configuration. )
962 config NR_CPUS_RANGE_BEGIN
964 default NR_CPUS_RANGE_END if MAXSMP
968 config NR_CPUS_RANGE_END
971 default 64 if SMP && X86_BIGSMP
972 default 8 if SMP && !X86_BIGSMP
975 config NR_CPUS_RANGE_END
978 default 8192 if SMP && CPUMASK_OFFSTACK
979 default 512 if SMP && !CPUMASK_OFFSTACK
982 config NR_CPUS_DEFAULT
985 default 32 if X86_BIGSMP
989 config NR_CPUS_DEFAULT
992 default 8192 if MAXSMP
997 int "Maximum number of CPUs" if SMP && !MAXSMP
998 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
999 default NR_CPUS_DEFAULT
1001 This allows you to specify the maximum number of CPUs which this
1002 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1003 supported value is 8192, otherwise the maximum value is 512. The
1004 minimum value which makes sense is 2.
1006 This is purely to save memory: each supported CPU adds about 8KB
1007 to the kernel image.
1014 prompt "Multi-core scheduler support"
1017 Multi-core scheduler support improves the CPU scheduler's decision
1018 making when dealing with multi-core CPU chips at a cost of slightly
1019 increased overhead in some places. If unsure say N here.
1021 config SCHED_MC_PRIO
1022 bool "CPU core priorities scheduler support"
1023 depends on SCHED_MC && CPU_SUP_INTEL
1024 select X86_INTEL_PSTATE
1028 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1029 core ordering determined at manufacturing time, which allows
1030 certain cores to reach higher turbo frequencies (when running
1031 single threaded workloads) than others.
1033 Enabling this kernel feature teaches the scheduler about
1034 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1035 scheduler's CPU selection logic accordingly, so that higher
1036 overall system performance can be achieved.
1038 This feature will have no effect on CPUs without this feature.
1040 If unsure say Y here.
1044 depends on !SMP && X86_LOCAL_APIC
1047 bool "Local APIC support on uniprocessors" if !PCI_MSI
1049 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1051 A local APIC (Advanced Programmable Interrupt Controller) is an
1052 integrated interrupt controller in the CPU. If you have a single-CPU
1053 system which has a processor with a local APIC, you can say Y here to
1054 enable and use it. If you say Y here even though your machine doesn't
1055 have a local APIC, then the kernel will still run with no slowdown at
1056 all. The local APIC supports CPU-generated self-interrupts (timer,
1057 performance counters), and the NMI watchdog which detects hard
1060 config X86_UP_IOAPIC
1061 bool "IO-APIC support on uniprocessors"
1062 depends on X86_UP_APIC
1064 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1065 SMP-capable replacement for PC-style interrupt controllers. Most
1066 SMP systems and many recent uniprocessor systems have one.
1068 If you have a single-CPU system with an IO-APIC, you can say Y here
1069 to use it. If you say Y here even though your machine doesn't have
1070 an IO-APIC, then the kernel will still run with no slowdown at all.
1072 config X86_LOCAL_APIC
1074 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1075 select IRQ_DOMAIN_HIERARCHY
1076 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1080 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1082 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1083 bool "Reroute for broken boot IRQs"
1084 depends on X86_IO_APIC
1086 This option enables a workaround that fixes a source of
1087 spurious interrupts. This is recommended when threaded
1088 interrupt handling is used on systems where the generation of
1089 superfluous "boot interrupts" cannot be disabled.
1091 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1092 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1093 kernel does during interrupt handling). On chipsets where this
1094 boot IRQ generation cannot be disabled, this workaround keeps
1095 the original IRQ line masked so that only the equivalent "boot
1096 IRQ" is delivered to the CPUs. The workaround also tells the
1097 kernel to set up the IRQ handler on the boot IRQ line. In this
1098 way only one interrupt is delivered to the kernel. Otherwise
1099 the spurious second interrupt may cause the kernel to bring
1100 down (vital) interrupt lines.
1102 Only affects "broken" chipsets. Interrupt sharing may be
1103 increased on these systems.
1106 bool "Machine Check / overheating reporting"
1107 select GENERIC_ALLOCATOR
1110 Machine Check support allows the processor to notify the
1111 kernel if it detects a problem (e.g. overheating, data corruption).
1112 The action the kernel takes depends on the severity of the problem,
1113 ranging from warning messages to halting the machine.
1115 config X86_MCELOG_LEGACY
1116 bool "Support for deprecated /dev/mcelog character device"
1119 Enable support for /dev/mcelog which is needed by the old mcelog
1120 userspace logging daemon. Consider switching to the new generation
1123 config X86_MCE_INTEL
1125 prompt "Intel MCE features"
1126 depends on X86_MCE && X86_LOCAL_APIC
1128 Additional support for intel specific MCE features such as
1129 the thermal monitor.
1133 prompt "AMD MCE features"
1134 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1136 Additional support for AMD specific MCE features such as
1137 the DRAM Error Threshold.
1139 config X86_ANCIENT_MCE
1140 bool "Support for old Pentium 5 / WinChip machine checks"
1141 depends on X86_32 && X86_MCE
1143 Include support for machine check handling on old Pentium 5 or WinChip
1144 systems. These typically need to be enabled explicitly on the command
1147 config X86_MCE_THRESHOLD
1148 depends on X86_MCE_AMD || X86_MCE_INTEL
1151 config X86_MCE_INJECT
1152 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1153 tristate "Machine check injector support"
1155 Provide support for injecting machine checks for testing purposes.
1156 If you don't know what a machine check is and you don't do kernel
1157 QA it is safe to say n.
1159 config X86_THERMAL_VECTOR
1161 depends on X86_MCE_INTEL
1163 source "arch/x86/events/Kconfig"
1165 config X86_LEGACY_VM86
1166 bool "Legacy VM86 support"
1169 This option allows user programs to put the CPU into V8086
1170 mode, which is an 80286-era approximation of 16-bit real mode.
1172 Some very old versions of X and/or vbetool require this option
1173 for user mode setting. Similarly, DOSEMU will use it if
1174 available to accelerate real mode DOS programs. However, any
1175 recent version of DOSEMU, X, or vbetool should be fully
1176 functional even without kernel VM86 support, as they will all
1177 fall back to software emulation. Nevertheless, if you are using
1178 a 16-bit DOS program where 16-bit performance matters, vm86
1179 mode might be faster than emulation and you might want to
1182 Note that any app that works on a 64-bit kernel is unlikely to
1183 need this option, as 64-bit kernels don't, and can't, support
1184 V8086 mode. This option is also unrelated to 16-bit protected
1185 mode and is not needed to run most 16-bit programs under Wine.
1187 Enabling this option increases the complexity of the kernel
1188 and slows down exception handling a tiny bit.
1190 If unsure, say N here.
1194 default X86_LEGACY_VM86
1197 bool "Enable support for 16-bit segments" if EXPERT
1199 depends on MODIFY_LDT_SYSCALL
1201 This option is required by programs like Wine to run 16-bit
1202 protected mode legacy code on x86 processors. Disabling
1203 this option saves about 300 bytes on i386, or around 6K text
1204 plus 16K runtime memory on x86-64,
1208 depends on X86_16BIT && X86_32
1212 depends on X86_16BIT && X86_64
1214 config X86_VSYSCALL_EMULATION
1215 bool "Enable vsyscall emulation" if EXPERT
1219 This enables emulation of the legacy vsyscall page. Disabling
1220 it is roughly equivalent to booting with vsyscall=none, except
1221 that it will also disable the helpful warning if a program
1222 tries to use a vsyscall. With this option set to N, offending
1223 programs will just segfault, citing addresses of the form
1226 This option is required by many programs built before 2013, and
1227 care should be used even with newer programs if set to N.
1229 Disabling this option saves about 7K of kernel size and
1230 possibly 4K of additional runtime pagetable memory.
1232 config X86_IOPL_IOPERM
1233 bool "IOPERM and IOPL Emulation"
1236 This enables the ioperm() and iopl() syscalls which are necessary
1237 for legacy applications.
1239 Legacy IOPL support is an overbroad mechanism which allows user
1240 space aside of accessing all 65536 I/O ports also to disable
1241 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1242 capabilities and permission from potentially active security
1245 The emulation restricts the functionality of the syscall to
1246 only allowing the full range I/O port access, but prevents the
1247 ability to disable interrupts from user space which would be
1248 granted if the hardware IOPL mechanism would be used.
1251 tristate "Toshiba Laptop support"
1254 This adds a driver to safely access the System Management Mode of
1255 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1256 not work on models with a Phoenix BIOS. The System Management Mode
1257 is used to set the BIOS and power saving options on Toshiba portables.
1259 For information on utilities to make use of this driver see the
1260 Toshiba Linux utilities web site at:
1261 <http://www.buzzard.org.uk/toshiba/>.
1263 Say Y if you intend to run this kernel on a Toshiba portable.
1267 tristate "Dell i8k legacy laptop support"
1269 select SENSORS_DELL_SMM
1271 This option enables legacy /proc/i8k userspace interface in hwmon
1272 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1273 temperature and allows controlling fan speeds of Dell laptops via
1274 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1275 it reports also power and hotkey status. For fan speed control is
1276 needed userspace package i8kutils.
1278 Say Y if you intend to run this kernel on old Dell laptops or want to
1279 use userspace package i8kutils.
1282 config X86_REBOOTFIXUPS
1283 bool "Enable X86 board specific fixups for reboot"
1286 This enables chipset and/or board specific fixups to be done
1287 in order to get reboot to work correctly. This is only needed on
1288 some combinations of hardware and BIOS. The symptom, for which
1289 this config is intended, is when reboot ends with a stalled/hung
1292 Currently, the only fixup is for the Geode machines using
1293 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1295 Say Y if you want to enable the fixup. Currently, it's safe to
1296 enable this option even if you don't need it.
1300 bool "CPU microcode loading support"
1302 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1305 If you say Y here, you will be able to update the microcode on
1306 Intel and AMD processors. The Intel support is for the IA32 family,
1307 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1308 AMD support is for families 0x10 and later. You will obviously need
1309 the actual microcode binary data itself which is not shipped with
1312 The preferred method to load microcode from a detached initrd is described
1313 in Documentation/x86/microcode.rst. For that you need to enable
1314 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1315 initrd for microcode blobs.
1317 In addition, you can build the microcode into the kernel. For that you
1318 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1321 config MICROCODE_INTEL
1322 bool "Intel microcode loading support"
1323 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
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 !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !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
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 "EFI runtime service support"
1941 select EFI_RUNTIME_WRAPPERS
1943 This enables the kernel to use EFI runtime services that are
1944 available (such as the EFI variable services).
1946 This option is only useful on systems that have EFI firmware.
1947 In addition, you should use the latest ELILO loader available
1948 at <http://elilo.sourceforge.net> in order to take advantage
1949 of EFI runtime services. However, even with this option, the
1950 resultant kernel should continue to boot on existing non-EFI
1954 bool "EFI stub support"
1955 depends on EFI && !X86_USE_3DNOW
1956 depends on $(cc-option,-mabi=ms) || X86_32
1959 This kernel feature allows a bzImage to be loaded directly
1960 by EFI firmware without the use of a bootloader.
1962 See Documentation/admin-guide/efi-stub.rst for more information.
1965 bool "EFI mixed-mode support"
1966 depends on EFI_STUB && X86_64
1968 Enabling this feature allows a 64-bit kernel to be booted
1969 on a 32-bit firmware, provided that your CPU supports 64-bit
1972 Note that it is not possible to boot a mixed-mode enabled
1973 kernel via the EFI boot stub - a bootloader that supports
1974 the EFI handover protocol must be used.
1980 prompt "Enable seccomp to safely compute untrusted bytecode"
1982 This kernel feature is useful for number crunching applications
1983 that may need to compute untrusted bytecode during their
1984 execution. By using pipes or other transports made available to
1985 the process as file descriptors supporting the read/write
1986 syscalls, it's possible to isolate those applications in
1987 their own address space using seccomp. Once seccomp is
1988 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1989 and the task is only allowed to execute a few safe syscalls
1990 defined by each seccomp mode.
1992 If unsure, say Y. Only embedded should say N here.
1994 source "kernel/Kconfig.hz"
1997 bool "kexec system call"
2000 kexec is a system call that implements the ability to shutdown your
2001 current kernel, and to start another kernel. It is like a reboot
2002 but it is independent of the system firmware. And like a reboot
2003 you can start any kernel with it, not just Linux.
2005 The name comes from the similarity to the exec system call.
2007 It is an ongoing process to be certain the hardware in a machine
2008 is properly shutdown, so do not be surprised if this code does not
2009 initially work for you. As of this writing the exact hardware
2010 interface is strongly in flux, so no good recommendation can be
2014 bool "kexec file based system call"
2019 depends on CRYPTO_SHA256=y
2021 This is new version of kexec system call. This system call is
2022 file based and takes file descriptors as system call argument
2023 for kernel and initramfs as opposed to list of segments as
2024 accepted by previous system call.
2026 config ARCH_HAS_KEXEC_PURGATORY
2030 bool "Verify kernel signature during kexec_file_load() syscall"
2031 depends on KEXEC_FILE
2034 This option makes the kexec_file_load() syscall check for a valid
2035 signature of the kernel image. The image can still be loaded without
2036 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2037 there's a signature that we can check, then it must be valid.
2039 In addition to this option, you need to enable signature
2040 verification for the corresponding kernel image type being
2041 loaded in order for this to work.
2043 config KEXEC_SIG_FORCE
2044 bool "Require a valid signature in kexec_file_load() syscall"
2045 depends on KEXEC_SIG
2047 This option makes kernel signature verification mandatory for
2048 the kexec_file_load() syscall.
2050 config KEXEC_BZIMAGE_VERIFY_SIG
2051 bool "Enable bzImage signature verification support"
2052 depends on KEXEC_SIG
2053 depends on SIGNED_PE_FILE_VERIFICATION
2054 select SYSTEM_TRUSTED_KEYRING
2056 Enable bzImage signature verification support.
2059 bool "kernel crash dumps"
2060 depends on X86_64 || (X86_32 && HIGHMEM)
2062 Generate crash dump after being started by kexec.
2063 This should be normally only set in special crash dump kernels
2064 which are loaded in the main kernel with kexec-tools into
2065 a specially reserved region and then later executed after
2066 a crash by kdump/kexec. The crash dump kernel must be compiled
2067 to a memory address not used by the main kernel or BIOS using
2068 PHYSICAL_START, or it must be built as a relocatable image
2069 (CONFIG_RELOCATABLE=y).
2070 For more details see Documentation/admin-guide/kdump/kdump.rst
2074 depends on KEXEC && HIBERNATION
2076 Jump between original kernel and kexeced kernel and invoke
2077 code in physical address mode via KEXEC
2079 config PHYSICAL_START
2080 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2083 This gives the physical address where the kernel is loaded.
2085 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2086 bzImage will decompress itself to above physical address and
2087 run from there. Otherwise, bzImage will run from the address where
2088 it has been loaded by the boot loader and will ignore above physical
2091 In normal kdump cases one does not have to set/change this option
2092 as now bzImage can be compiled as a completely relocatable image
2093 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2094 address. This option is mainly useful for the folks who don't want
2095 to use a bzImage for capturing the crash dump and want to use a
2096 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2097 to be specifically compiled to run from a specific memory area
2098 (normally a reserved region) and this option comes handy.
2100 So if you are using bzImage for capturing the crash dump,
2101 leave the value here unchanged to 0x1000000 and set
2102 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2103 for capturing the crash dump change this value to start of
2104 the reserved region. In other words, it can be set based on
2105 the "X" value as specified in the "crashkernel=YM@XM"
2106 command line boot parameter passed to the panic-ed
2107 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2108 for more details about crash dumps.
2110 Usage of bzImage for capturing the crash dump is recommended as
2111 one does not have to build two kernels. Same kernel can be used
2112 as production kernel and capture kernel. Above option should have
2113 gone away after relocatable bzImage support is introduced. But it
2114 is present because there are users out there who continue to use
2115 vmlinux for dump capture. This option should go away down the
2118 Don't change this unless you know what you are doing.
2121 bool "Build a relocatable kernel"
2124 This builds a kernel image that retains relocation information
2125 so it can be loaded someplace besides the default 1MB.
2126 The relocations tend to make the kernel binary about 10% larger,
2127 but are discarded at runtime.
2129 One use is for the kexec on panic case where the recovery kernel
2130 must live at a different physical address than the primary
2133 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2134 it has been loaded at and the compile time physical address
2135 (CONFIG_PHYSICAL_START) is used as the minimum location.
2137 config RANDOMIZE_BASE
2138 bool "Randomize the address of the kernel image (KASLR)"
2139 depends on RELOCATABLE
2142 In support of Kernel Address Space Layout Randomization (KASLR),
2143 this randomizes the physical address at which the kernel image
2144 is decompressed and the virtual address where the kernel
2145 image is mapped, as a security feature that deters exploit
2146 attempts relying on knowledge of the location of kernel
2149 On 64-bit, the kernel physical and virtual addresses are
2150 randomized separately. The physical address will be anywhere
2151 between 16MB and the top of physical memory (up to 64TB). The
2152 virtual address will be randomized from 16MB up to 1GB (9 bits
2153 of entropy). Note that this also reduces the memory space
2154 available to kernel modules from 1.5GB to 1GB.
2156 On 32-bit, the kernel physical and virtual addresses are
2157 randomized together. They will be randomized from 16MB up to
2158 512MB (8 bits of entropy).
2160 Entropy is generated using the RDRAND instruction if it is
2161 supported. If RDTSC is supported, its value is mixed into
2162 the entropy pool as well. If neither RDRAND nor RDTSC are
2163 supported, then entropy is read from the i8254 timer. The
2164 usable entropy is limited by the kernel being built using
2165 2GB addressing, and that PHYSICAL_ALIGN must be at a
2166 minimum of 2MB. As a result, only 10 bits of entropy are
2167 theoretically possible, but the implementations are further
2168 limited due to memory layouts.
2172 # Relocation on x86 needs some additional build support
2173 config X86_NEED_RELOCS
2175 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2177 config PHYSICAL_ALIGN
2178 hex "Alignment value to which kernel should be aligned"
2180 range 0x2000 0x1000000 if X86_32
2181 range 0x200000 0x1000000 if X86_64
2183 This value puts the alignment restrictions on physical address
2184 where kernel is loaded and run from. Kernel is compiled for an
2185 address which meets above alignment restriction.
2187 If bootloader loads the kernel at a non-aligned address and
2188 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2189 address aligned to above value and run from there.
2191 If bootloader loads the kernel at a non-aligned address and
2192 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2193 load address and decompress itself to the address it has been
2194 compiled for and run from there. The address for which kernel is
2195 compiled already meets above alignment restrictions. Hence the
2196 end result is that kernel runs from a physical address meeting
2197 above alignment restrictions.
2199 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2200 this value must be a multiple of 0x200000.
2202 Don't change this unless you know what you are doing.
2204 config DYNAMIC_MEMORY_LAYOUT
2207 This option makes base addresses of vmalloc and vmemmap as well as
2208 __PAGE_OFFSET movable during boot.
2210 config RANDOMIZE_MEMORY
2211 bool "Randomize the kernel memory sections"
2213 depends on RANDOMIZE_BASE
2214 select DYNAMIC_MEMORY_LAYOUT
2215 default RANDOMIZE_BASE
2217 Randomizes the base virtual address of kernel memory sections
2218 (physical memory mapping, vmalloc & vmemmap). This security feature
2219 makes exploits relying on predictable memory locations less reliable.
2221 The order of allocations remains unchanged. Entropy is generated in
2222 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2223 configuration have in average 30,000 different possible virtual
2224 addresses for each memory section.
2228 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2229 hex "Physical memory mapping padding" if EXPERT
2230 depends on RANDOMIZE_MEMORY
2231 default "0xa" if MEMORY_HOTPLUG
2233 range 0x1 0x40 if MEMORY_HOTPLUG
2236 Define the padding in terabytes added to the existing physical
2237 memory size during kernel memory randomization. It is useful
2238 for memory hotplug support but reduces the entropy available for
2239 address randomization.
2241 If unsure, leave at the default value.
2247 config BOOTPARAM_HOTPLUG_CPU0
2248 bool "Set default setting of cpu0_hotpluggable"
2249 depends on HOTPLUG_CPU
2251 Set whether default state of cpu0_hotpluggable is on or off.
2253 Say Y here to enable CPU0 hotplug by default. If this switch
2254 is turned on, there is no need to give cpu0_hotplug kernel
2255 parameter and the CPU0 hotplug feature is enabled by default.
2257 Please note: there are two known CPU0 dependencies if you want
2258 to enable the CPU0 hotplug feature either by this switch or by
2259 cpu0_hotplug kernel parameter.
2261 First, resume from hibernate or suspend always starts from CPU0.
2262 So hibernate and suspend are prevented if CPU0 is offline.
2264 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2265 offline if any interrupt can not migrate out of CPU0. There may
2266 be other CPU0 dependencies.
2268 Please make sure the dependencies are under your control before
2269 you enable this feature.
2271 Say N if you don't want to enable CPU0 hotplug feature by default.
2272 You still can enable the CPU0 hotplug feature at boot by kernel
2273 parameter cpu0_hotplug.
2275 config DEBUG_HOTPLUG_CPU0
2277 prompt "Debug CPU0 hotplug"
2278 depends on HOTPLUG_CPU
2280 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2281 soon as possible and boots up userspace with CPU0 offlined. User
2282 can online CPU0 back after boot time.
2284 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2285 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2286 compilation or giving cpu0_hotplug kernel parameter at boot.
2292 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2293 depends on COMPAT_32
2295 Certain buggy versions of glibc will crash if they are
2296 presented with a 32-bit vDSO that is not mapped at the address
2297 indicated in its segment table.
2299 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2300 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2301 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2302 the only released version with the bug, but OpenSUSE 9
2303 contains a buggy "glibc 2.3.2".
2305 The symptom of the bug is that everything crashes on startup, saying:
2306 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2308 Saying Y here changes the default value of the vdso32 boot
2309 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2310 This works around the glibc bug but hurts performance.
2312 If unsure, say N: if you are compiling your own kernel, you
2313 are unlikely to be using a buggy version of glibc.
2316 prompt "vsyscall table for legacy applications"
2318 default LEGACY_VSYSCALL_XONLY
2320 Legacy user code that does not know how to find the vDSO expects
2321 to be able to issue three syscalls by calling fixed addresses in
2322 kernel space. Since this location is not randomized with ASLR,
2323 it can be used to assist security vulnerability exploitation.
2325 This setting can be changed at boot time via the kernel command
2326 line parameter vsyscall=[emulate|xonly|none].
2328 On a system with recent enough glibc (2.14 or newer) and no
2329 static binaries, you can say None without a performance penalty
2330 to improve security.
2332 If unsure, select "Emulate execution only".
2334 config LEGACY_VSYSCALL_EMULATE
2335 bool "Full emulation"
2337 The kernel traps and emulates calls into the fixed vsyscall
2338 address mapping. This makes the mapping non-executable, but
2339 it still contains readable known contents, which could be
2340 used in certain rare security vulnerability exploits. This
2341 configuration is recommended when using legacy userspace
2342 that still uses vsyscalls along with legacy binary
2343 instrumentation tools that require code to be readable.
2345 An example of this type of legacy userspace is running
2346 Pin on an old binary that still uses vsyscalls.
2348 config LEGACY_VSYSCALL_XONLY
2349 bool "Emulate execution only"
2351 The kernel traps and emulates calls into the fixed vsyscall
2352 address mapping and does not allow reads. This
2353 configuration is recommended when userspace might use the
2354 legacy vsyscall area but support for legacy binary
2355 instrumentation of legacy code is not needed. It mitigates
2356 certain uses of the vsyscall area as an ASLR-bypassing
2359 config LEGACY_VSYSCALL_NONE
2362 There will be no vsyscall mapping at all. This will
2363 eliminate any risk of ASLR bypass due to the vsyscall
2364 fixed address mapping. Attempts to use the vsyscalls
2365 will be reported to dmesg, so that either old or
2366 malicious userspace programs can be identified.
2371 bool "Built-in kernel command line"
2373 Allow for specifying boot arguments to the kernel at
2374 build time. On some systems (e.g. embedded ones), it is
2375 necessary or convenient to provide some or all of the
2376 kernel boot arguments with the kernel itself (that is,
2377 to not rely on the boot loader to provide them.)
2379 To compile command line arguments into the kernel,
2380 set this option to 'Y', then fill in the
2381 boot arguments in CONFIG_CMDLINE.
2383 Systems with fully functional boot loaders (i.e. non-embedded)
2384 should leave this option set to 'N'.
2387 string "Built-in kernel command string"
2388 depends on CMDLINE_BOOL
2391 Enter arguments here that should be compiled into the kernel
2392 image and used at boot time. If the boot loader provides a
2393 command line at boot time, it is appended to this string to
2394 form the full kernel command line, when the system boots.
2396 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2397 change this behavior.
2399 In most cases, the command line (whether built-in or provided
2400 by the boot loader) should specify the device for the root
2403 config CMDLINE_OVERRIDE
2404 bool "Built-in command line overrides boot loader arguments"
2405 depends on CMDLINE_BOOL && CMDLINE != ""
2407 Set this option to 'Y' to have the kernel ignore the boot loader
2408 command line, and use ONLY the built-in command line.
2410 This is used to work around broken boot loaders. This should
2411 be set to 'N' under normal conditions.
2413 config MODIFY_LDT_SYSCALL
2414 bool "Enable the LDT (local descriptor table)" if EXPERT
2417 Linux can allow user programs to install a per-process x86
2418 Local Descriptor Table (LDT) using the modify_ldt(2) system
2419 call. This is required to run 16-bit or segmented code such as
2420 DOSEMU or some Wine programs. It is also used by some very old
2421 threading libraries.
2423 Enabling this feature adds a small amount of overhead to
2424 context switches and increases the low-level kernel attack
2425 surface. Disabling it removes the modify_ldt(2) system call.
2427 Saying 'N' here may make sense for embedded or server kernels.
2429 source "kernel/livepatch/Kconfig"
2433 config ARCH_HAS_ADD_PAGES
2435 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2437 config ARCH_ENABLE_MEMORY_HOTPLUG
2439 depends on X86_64 || (X86_32 && HIGHMEM)
2441 config ARCH_ENABLE_MEMORY_HOTREMOVE
2443 depends on MEMORY_HOTPLUG
2445 config USE_PERCPU_NUMA_NODE_ID
2449 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2451 depends on X86_64 || X86_PAE
2453 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2455 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2457 config ARCH_ENABLE_THP_MIGRATION
2459 depends on X86_64 && TRANSPARENT_HUGEPAGE
2461 menu "Power management and ACPI options"
2463 config ARCH_HIBERNATION_HEADER
2465 depends on HIBERNATION
2467 source "kernel/power/Kconfig"
2469 source "drivers/acpi/Kconfig"
2471 source "drivers/sfi/Kconfig"
2478 tristate "APM (Advanced Power Management) BIOS support"
2479 depends on X86_32 && PM_SLEEP
2481 APM is a BIOS specification for saving power using several different
2482 techniques. This is mostly useful for battery powered laptops with
2483 APM compliant BIOSes. If you say Y here, the system time will be
2484 reset after a RESUME operation, the /proc/apm device will provide
2485 battery status information, and user-space programs will receive
2486 notification of APM "events" (e.g. battery status change).
2488 If you select "Y" here, you can disable actual use of the APM
2489 BIOS by passing the "apm=off" option to the kernel at boot time.
2491 Note that the APM support is almost completely disabled for
2492 machines with more than one CPU.
2494 In order to use APM, you will need supporting software. For location
2495 and more information, read <file:Documentation/power/apm-acpi.rst>
2496 and the Battery Powered Linux mini-HOWTO, available from
2497 <http://www.tldp.org/docs.html#howto>.
2499 This driver does not spin down disk drives (see the hdparm(8)
2500 manpage ("man 8 hdparm") for that), and it doesn't turn off
2501 VESA-compliant "green" monitors.
2503 This driver does not support the TI 4000M TravelMate and the ACER
2504 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2505 desktop machines also don't have compliant BIOSes, and this driver
2506 may cause those machines to panic during the boot phase.
2508 Generally, if you don't have a battery in your machine, there isn't
2509 much point in using this driver and you should say N. If you get
2510 random kernel OOPSes or reboots that don't seem to be related to
2511 anything, try disabling/enabling this option (or disabling/enabling
2514 Some other things you should try when experiencing seemingly random,
2517 1) make sure that you have enough swap space and that it is
2519 2) pass the "no-hlt" option to the kernel
2520 3) switch on floating point emulation in the kernel and pass
2521 the "no387" option to the kernel
2522 4) pass the "floppy=nodma" option to the kernel
2523 5) pass the "mem=4M" option to the kernel (thereby disabling
2524 all but the first 4 MB of RAM)
2525 6) make sure that the CPU is not over clocked.
2526 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2527 8) disable the cache from your BIOS settings
2528 9) install a fan for the video card or exchange video RAM
2529 10) install a better fan for the CPU
2530 11) exchange RAM chips
2531 12) exchange the motherboard.
2533 To compile this driver as a module, choose M here: the
2534 module will be called apm.
2538 config APM_IGNORE_USER_SUSPEND
2539 bool "Ignore USER SUSPEND"
2541 This option will ignore USER SUSPEND requests. On machines with a
2542 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2543 series notebooks, it is necessary to say Y because of a BIOS bug.
2545 config APM_DO_ENABLE
2546 bool "Enable PM at boot time"
2548 Enable APM features at boot time. From page 36 of the APM BIOS
2549 specification: "When disabled, the APM BIOS does not automatically
2550 power manage devices, enter the Standby State, enter the Suspend
2551 State, or take power saving steps in response to CPU Idle calls."
2552 This driver will make CPU Idle calls when Linux is idle (unless this
2553 feature is turned off -- see "Do CPU IDLE calls", below). This
2554 should always save battery power, but more complicated APM features
2555 will be dependent on your BIOS implementation. You may need to turn
2556 this option off if your computer hangs at boot time when using APM
2557 support, or if it beeps continuously instead of suspending. Turn
2558 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2559 T400CDT. This is off by default since most machines do fine without
2564 bool "Make CPU Idle calls when idle"
2566 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2567 On some machines, this can activate improved power savings, such as
2568 a slowed CPU clock rate, when the machine is idle. These idle calls
2569 are made after the idle loop has run for some length of time (e.g.,
2570 333 mS). On some machines, this will cause a hang at boot time or
2571 whenever the CPU becomes idle. (On machines with more than one CPU,
2572 this option does nothing.)
2574 config APM_DISPLAY_BLANK
2575 bool "Enable console blanking using APM"
2577 Enable console blanking using the APM. Some laptops can use this to
2578 turn off the LCD backlight when the screen blanker of the Linux
2579 virtual console blanks the screen. Note that this is only used by
2580 the virtual console screen blanker, and won't turn off the backlight
2581 when using the X Window system. This also doesn't have anything to
2582 do with your VESA-compliant power-saving monitor. Further, this
2583 option doesn't work for all laptops -- it might not turn off your
2584 backlight at all, or it might print a lot of errors to the console,
2585 especially if you are using gpm.
2587 config APM_ALLOW_INTS
2588 bool "Allow interrupts during APM BIOS calls"
2590 Normally we disable external interrupts while we are making calls to
2591 the APM BIOS as a measure to lessen the effects of a badly behaving
2592 BIOS implementation. The BIOS should reenable interrupts if it
2593 needs to. Unfortunately, some BIOSes do not -- especially those in
2594 many of the newer IBM Thinkpads. If you experience hangs when you
2595 suspend, try setting this to Y. Otherwise, say N.
2599 source "drivers/cpufreq/Kconfig"
2601 source "drivers/cpuidle/Kconfig"
2603 source "drivers/idle/Kconfig"
2608 menu "Bus options (PCI etc.)"
2611 prompt "PCI access mode"
2612 depends on X86_32 && PCI
2615 On PCI systems, the BIOS can be used to detect the PCI devices and
2616 determine their configuration. However, some old PCI motherboards
2617 have BIOS bugs and may crash if this is done. Also, some embedded
2618 PCI-based systems don't have any BIOS at all. Linux can also try to
2619 detect the PCI hardware directly without using the BIOS.
2621 With this option, you can specify how Linux should detect the
2622 PCI devices. If you choose "BIOS", the BIOS will be used,
2623 if you choose "Direct", the BIOS won't be used, and if you
2624 choose "MMConfig", then PCI Express MMCONFIG will be used.
2625 If you choose "Any", the kernel will try MMCONFIG, then the
2626 direct access method and falls back to the BIOS if that doesn't
2627 work. If unsure, go with the default, which is "Any".
2632 config PCI_GOMMCONFIG
2649 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2651 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2654 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2657 bool "Support mmconfig PCI config space access" if X86_64
2659 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2660 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2664 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2668 depends on PCI && XEN
2671 config MMCONF_FAM10H
2673 depends on X86_64 && PCI_MMCONFIG && ACPI
2675 config PCI_CNB20LE_QUIRK
2676 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2679 Read the PCI windows out of the CNB20LE host bridge. This allows
2680 PCI hotplug to work on systems with the CNB20LE chipset which do
2683 There's no public spec for this chipset, and this functionality
2684 is known to be incomplete.
2686 You should say N unless you know you need this.
2689 bool "ISA bus support on modern systems" if EXPERT
2691 Expose ISA bus device drivers and options available for selection and
2692 configuration. Enable this option if your target machine has an ISA
2693 bus. ISA is an older system, displaced by PCI and newer bus
2694 architectures -- if your target machine is modern, it probably does
2695 not have an ISA bus.
2699 # x86_64 have no ISA slots, but can have ISA-style DMA.
2701 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2704 Enables ISA-style DMA support for devices requiring such controllers.
2712 Find out whether you have ISA slots on your motherboard. ISA is the
2713 name of a bus system, i.e. the way the CPU talks to the other stuff
2714 inside your box. Other bus systems are PCI, EISA, MicroChannel
2715 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2716 newer boards don't support it. If you have ISA, say Y, otherwise N.
2719 tristate "NatSemi SCx200 support"
2721 This provides basic support for National Semiconductor's
2722 (now AMD's) Geode processors. The driver probes for the
2723 PCI-IDs of several on-chip devices, so its a good dependency
2724 for other scx200_* drivers.
2726 If compiled as a module, the driver is named scx200.
2728 config SCx200HR_TIMER
2729 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2733 This driver provides a clocksource built upon the on-chip
2734 27MHz high-resolution timer. Its also a workaround for
2735 NSC Geode SC-1100's buggy TSC, which loses time when the
2736 processor goes idle (as is done by the scheduler). The
2737 other workaround is idle=poll boot option.
2740 bool "One Laptop Per Child support"
2748 Add support for detecting the unique features of the OLPC
2752 bool "OLPC XO-1 Power Management"
2753 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2755 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2758 bool "OLPC XO-1 Real Time Clock"
2759 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2761 Add support for the XO-1 real time clock, which can be used as a
2762 programmable wakeup source.
2765 bool "OLPC XO-1 SCI extras"
2766 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2770 Add support for SCI-based features of the OLPC XO-1 laptop:
2771 - EC-driven system wakeups
2775 - AC adapter status updates
2776 - Battery status updates
2778 config OLPC_XO15_SCI
2779 bool "OLPC XO-1.5 SCI extras"
2780 depends on OLPC && ACPI
2783 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2784 - EC-driven system wakeups
2785 - AC adapter status updates
2786 - Battery status updates
2789 bool "PCEngines ALIX System Support (LED setup)"
2792 This option enables system support for the PCEngines ALIX.
2793 At present this just sets up LEDs for GPIO control on
2794 ALIX2/3/6 boards. However, other system specific setup should
2797 Note: You must still enable the drivers for GPIO and LED support
2798 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2800 Note: You have to set alix.force=1 for boards with Award BIOS.
2803 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2806 This option enables system support for the Soekris Engineering net5501.
2809 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2813 This option enables system support for the Traverse Technologies GEOS.
2816 bool "Technologic Systems TS-5500 platform support"
2818 select CHECK_SIGNATURE
2822 This option enables system support for the Technologic Systems TS-5500.
2828 depends on CPU_SUP_AMD && PCI
2831 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2833 Firmwares often provide initial graphics framebuffers so the BIOS,
2834 bootloader or kernel can show basic video-output during boot for
2835 user-guidance and debugging. Historically, x86 used the VESA BIOS
2836 Extensions and EFI-framebuffers for this, which are mostly limited
2838 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2839 framebuffers so the new generic system-framebuffer drivers can be
2840 used on x86. If the framebuffer is not compatible with the generic
2841 modes, it is advertised as fallback platform framebuffer so legacy
2842 drivers like efifb, vesafb and uvesafb can pick it up.
2843 If this option is not selected, all system framebuffers are always
2844 marked as fallback platform framebuffers as usual.
2846 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2847 not be able to pick up generic system framebuffers if this option
2848 is selected. You are highly encouraged to enable simplefb as
2849 replacement if you select this option. simplefb can correctly deal
2850 with generic system framebuffers. But you should still keep vesafb
2851 and others enabled as fallback if a system framebuffer is
2852 incompatible with simplefb.
2859 menu "Binary Emulations"
2861 config IA32_EMULATION
2862 bool "IA32 Emulation"
2864 select ARCH_WANT_OLD_COMPAT_IPC
2866 select COMPAT_BINFMT_ELF
2867 select COMPAT_OLD_SIGACTION
2869 Include code to run legacy 32-bit programs under a
2870 64-bit kernel. You should likely turn this on, unless you're
2871 100% sure that you don't have any 32-bit programs left.
2874 tristate "IA32 a.out support"
2875 depends on IA32_EMULATION
2878 Support old a.out binaries in the 32bit emulation.
2881 bool "x32 ABI for 64-bit mode"
2884 Include code to run binaries for the x32 native 32-bit ABI
2885 for 64-bit processors. An x32 process gets access to the
2886 full 64-bit register file and wide data path while leaving
2887 pointers at 32 bits for smaller memory footprint.
2889 You will need a recent binutils (2.22 or later) with
2890 elf32_x86_64 support enabled to compile a kernel with this
2895 depends on IA32_EMULATION || X86_32
2897 select OLD_SIGSUSPEND3
2901 depends on IA32_EMULATION || X86_X32
2904 config COMPAT_FOR_U64_ALIGNMENT
2907 config SYSVIPC_COMPAT
2915 config HAVE_ATOMIC_IOMAP
2919 source "drivers/firmware/Kconfig"
2921 source "arch/x86/kvm/Kconfig"
2923 source "arch/x86/Kconfig.assembler"