1 # SPDX-License-Identifier: GPL-2.0
4 bool "64-bit kernel" if "$(ARCH)" = "x86"
5 default "$(ARCH)" != "i386"
7 Say yes to build a 64-bit kernel - formerly known as x86_64
8 Say no to build a 32-bit kernel - formerly known as i386
13 # Options that are inherently 32-bit kernel only:
14 select ARCH_WANT_IPC_PARSE_VERSION
16 select CLONE_BACKWARDS
17 select HAVE_DEBUG_STACKOVERFLOW
18 select MODULES_USE_ELF_REL
20 select GENERIC_VDSO_32
25 # Options that are inherently 64-bit kernel only:
26 select ARCH_HAS_GIGANTIC_PAGE
27 select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
28 select ARCH_USE_CMPXCHG_LOCKREF
29 select HAVE_ARCH_SOFT_DIRTY
30 select MODULES_USE_ELF_RELA
31 select NEED_DMA_MAP_STATE
34 config FORCE_DYNAMIC_FTRACE
37 depends on FUNCTION_TRACER
40 We keep the static function tracing (!DYNAMIC_FTRACE) around
41 in order to test the non static function tracing in the
42 generic code, as other architectures still use it. But we
43 only need to keep it around for x86_64. No need to keep it
44 for x86_32. For x86_32, force DYNAMIC_FTRACE.
48 # ( Note that options that are marked 'if X86_64' could in principle be
49 # ported to 32-bit as well. )
54 # Note: keep this list sorted alphabetically
56 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
57 select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
58 select ARCH_32BIT_OFF_T if X86_32
59 select ARCH_CLOCKSOURCE_INIT
60 select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
61 select ARCH_HAS_DEBUG_VIRTUAL
62 select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
63 select ARCH_HAS_DEVMEM_IS_ALLOWED
64 select ARCH_HAS_EARLY_DEBUG if KGDB
65 select ARCH_HAS_ELF_RANDOMIZE
66 select ARCH_HAS_FAST_MULTIPLIER
67 select ARCH_HAS_FILTER_PGPROT
68 select ARCH_HAS_FORTIFY_SOURCE
69 select ARCH_HAS_GCOV_PROFILE_ALL
70 select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
71 select ARCH_HAS_MEM_ENCRYPT
72 select ARCH_HAS_MEMBARRIER_SYNC_CORE
73 select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
74 select ARCH_HAS_PMEM_API if X86_64
75 select ARCH_HAS_PTE_DEVMAP if X86_64
76 select ARCH_HAS_PTE_SPECIAL
77 select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
78 select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
79 select ARCH_HAS_SET_MEMORY
80 select ARCH_HAS_SET_DIRECT_MAP
81 select ARCH_HAS_STRICT_KERNEL_RWX
82 select ARCH_HAS_STRICT_MODULE_RWX
83 select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
84 select ARCH_HAS_SYSCALL_WRAPPER
85 select ARCH_HAS_UBSAN_SANITIZE_ALL
86 select ARCH_HAS_DEBUG_WX
87 select ARCH_HAVE_NMI_SAFE_CMPXCHG
88 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
89 select ARCH_MIGHT_HAVE_PC_PARPORT
90 select ARCH_MIGHT_HAVE_PC_SERIO
92 select ARCH_SUPPORTS_ACPI
93 select ARCH_SUPPORTS_ATOMIC_RMW
94 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
95 select ARCH_USE_BUILTIN_BSWAP
96 select ARCH_USE_QUEUED_RWLOCKS
97 select ARCH_USE_QUEUED_SPINLOCKS
98 select ARCH_USE_SYM_ANNOTATIONS
99 select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
100 select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
101 select ARCH_WANTS_DYNAMIC_TASK_STRUCT
102 select ARCH_WANT_HUGE_PMD_SHARE
103 select ARCH_WANTS_THP_SWAP if X86_64
104 select BUILDTIME_TABLE_SORT
106 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
107 select CLOCKSOURCE_WATCHDOG
108 select DCACHE_WORD_ACCESS
109 select EDAC_ATOMIC_SCRUB
111 select GENERIC_CLOCKEVENTS
112 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
113 select GENERIC_CLOCKEVENTS_MIN_ADJUST
114 select GENERIC_CMOS_UPDATE
115 select GENERIC_CPU_AUTOPROBE
116 select GENERIC_CPU_VULNERABILITIES
117 select GENERIC_EARLY_IOREMAP
119 select GENERIC_FIND_FIRST_BIT
121 select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
122 select GENERIC_IRQ_MATRIX_ALLOCATOR if X86_LOCAL_APIC
123 select GENERIC_IRQ_MIGRATION if SMP
124 select GENERIC_IRQ_PROBE
125 select GENERIC_IRQ_RESERVATION_MODE
126 select GENERIC_IRQ_SHOW
127 select GENERIC_PENDING_IRQ if SMP
128 select GENERIC_PTDUMP
129 select GENERIC_SMP_IDLE_THREAD
130 select GENERIC_STRNCPY_FROM_USER
131 select GENERIC_STRNLEN_USER
132 select GENERIC_TIME_VSYSCALL
133 select GENERIC_GETTIMEOFDAY
134 select GENERIC_VDSO_TIME_NS
135 select GUP_GET_PTE_LOW_HIGH if X86_PAE
136 select HARDIRQS_SW_RESEND
137 select HARDLOCKUP_CHECK_TIMESTAMP if X86_64
138 select HAVE_ACPI_APEI if ACPI
139 select HAVE_ACPI_APEI_NMI if ACPI
140 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
141 select HAVE_ARCH_AUDITSYSCALL
142 select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE
143 select HAVE_ARCH_JUMP_LABEL
144 select HAVE_ARCH_JUMP_LABEL_RELATIVE
145 select HAVE_ARCH_KASAN if X86_64
146 select HAVE_ARCH_KASAN_VMALLOC if X86_64
147 select HAVE_ARCH_KGDB
148 select HAVE_ARCH_MMAP_RND_BITS if MMU
149 select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
150 select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
151 select HAVE_ARCH_PREL32_RELOCATIONS
152 select HAVE_ARCH_SECCOMP_FILTER
153 select HAVE_ARCH_THREAD_STRUCT_WHITELIST
154 select HAVE_ARCH_STACKLEAK
155 select HAVE_ARCH_TRACEHOOK
156 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
157 select HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD if X86_64
158 select HAVE_ARCH_USERFAULTFD_WP if X86_64 && USERFAULTFD
159 select HAVE_ARCH_VMAP_STACK if X86_64
160 select HAVE_ARCH_WITHIN_STACK_FRAMES
161 select HAVE_ASM_MODVERSIONS
162 select HAVE_CMPXCHG_DOUBLE
163 select HAVE_CMPXCHG_LOCAL
164 select HAVE_CONTEXT_TRACKING if X86_64
165 select HAVE_C_RECORDMCOUNT
166 select HAVE_DEBUG_KMEMLEAK
167 select HAVE_DMA_CONTIGUOUS
168 select HAVE_DYNAMIC_FTRACE
169 select HAVE_DYNAMIC_FTRACE_WITH_REGS
170 select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
172 select HAVE_EFFICIENT_UNALIGNED_ACCESS
174 select HAVE_EXIT_THREAD
176 select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
177 select HAVE_FTRACE_MCOUNT_RECORD
178 select HAVE_FUNCTION_GRAPH_TRACER
179 select HAVE_FUNCTION_TRACER
180 select HAVE_GCC_PLUGINS
181 select HAVE_HW_BREAKPOINT
183 select HAVE_IOREMAP_PROT
184 select HAVE_IRQ_TIME_ACCOUNTING
185 select HAVE_KERNEL_BZIP2
186 select HAVE_KERNEL_GZIP
187 select HAVE_KERNEL_LZ4
188 select HAVE_KERNEL_LZMA
189 select HAVE_KERNEL_LZO
190 select HAVE_KERNEL_XZ
191 select HAVE_KERNEL_ZSTD
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_POSIX_CPU_TIMERS_TASK_WORK
213 select HAVE_REGS_AND_STACK_ACCESS_API
214 select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
215 select HAVE_FUNCTION_ARG_ACCESS_API
216 select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
217 select HAVE_STACK_VALIDATION if X86_64
219 select HAVE_SYSCALL_TRACEPOINTS
220 select HAVE_UNSTABLE_SCHED_CLOCK
221 select HAVE_USER_RETURN_NOTIFIER
222 select HAVE_GENERIC_VDSO
223 select HOTPLUG_SMT if SMP
224 select IRQ_FORCED_THREADING
225 select NEED_SG_DMA_LENGTH
226 select PCI_DOMAINS if PCI
227 select PCI_LOCKLESS_CONFIG if PCI
230 select RTC_MC146818_LIB
233 select SYSCTL_EXCEPTION_TRACE
234 select THREAD_INFO_IN_TASK
235 select USER_STACKTRACE_SUPPORT
237 select HAVE_ARCH_KCSAN if X86_64
238 select X86_FEATURE_NAMES if PROC_FS
239 select PROC_PID_ARCH_STATUS if PROC_FS
240 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
242 config INSTRUCTION_DECODER
244 depends on KPROBES || PERF_EVENTS || UPROBES
248 default "elf32-i386" if X86_32
249 default "elf64-x86-64" if X86_64
251 config LOCKDEP_SUPPORT
254 config STACKTRACE_SUPPORT
260 config ARCH_MMAP_RND_BITS_MIN
264 config ARCH_MMAP_RND_BITS_MAX
268 config ARCH_MMAP_RND_COMPAT_BITS_MIN
271 config ARCH_MMAP_RND_COMPAT_BITS_MAX
277 config GENERIC_ISA_DMA
279 depends on ISA_DMA_API
284 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
286 config GENERIC_BUG_RELATIVE_POINTERS
289 config ARCH_MAY_HAVE_PC_FDC
291 depends on ISA_DMA_API
293 config GENERIC_CALIBRATE_DELAY
296 config ARCH_HAS_CPU_RELAX
299 config ARCH_HAS_CACHE_LINE_SIZE
302 config ARCH_HAS_FILTER_PGPROT
305 config HAVE_SETUP_PER_CPU_AREA
308 config NEED_PER_CPU_EMBED_FIRST_CHUNK
311 config NEED_PER_CPU_PAGE_FIRST_CHUNK
314 config ARCH_HIBERNATION_POSSIBLE
317 config ARCH_SUSPEND_POSSIBLE
320 config ARCH_WANT_GENERAL_HUGETLB
329 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
332 config KASAN_SHADOW_OFFSET
335 default 0xdffffc0000000000
337 config HAVE_INTEL_TXT
339 depends on INTEL_IOMMU && ACPI
343 depends on X86_32 && SMP
347 depends on X86_64 && SMP
349 config X86_32_LAZY_GS
351 depends on X86_32 && !STACKPROTECTOR
353 config ARCH_SUPPORTS_UPROBES
356 config FIX_EARLYCON_MEM
359 config DYNAMIC_PHYSICAL_MASK
362 config PGTABLE_LEVELS
364 default 5 if X86_5LEVEL
369 config CC_HAS_SANE_STACKPROTECTOR
371 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
372 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
374 We have to make sure stack protector is unconditionally disabled if
375 the compiler produces broken code.
377 menu "Processor type and features"
380 bool "DMA memory allocation support" if EXPERT
383 DMA memory allocation support allows devices with less than 32-bit
384 addressing to allocate within the first 16MB of address space.
385 Disable if no such devices will be used.
390 bool "Symmetric multi-processing support"
392 This enables support for systems with more than one CPU. If you have
393 a system with only one CPU, say N. If you have a system with more
396 If you say N here, the kernel will run on uni- and multiprocessor
397 machines, but will use only one CPU of a multiprocessor machine. If
398 you say Y here, the kernel will run on many, but not all,
399 uniprocessor machines. On a uniprocessor machine, the kernel
400 will run faster if you say N here.
402 Note that if you say Y here and choose architecture "586" or
403 "Pentium" under "Processor family", the kernel will not work on 486
404 architectures. Similarly, multiprocessor kernels for the "PPro"
405 architecture may not work on all Pentium based boards.
407 People using multiprocessor machines who say Y here should also say
408 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
409 Management" code will be disabled if you say Y here.
411 See also <file:Documentation/x86/i386/IO-APIC.rst>,
412 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
413 <http://www.tldp.org/docs.html#howto>.
415 If you don't know what to do here, say N.
417 config X86_FEATURE_NAMES
418 bool "Processor feature human-readable names" if EMBEDDED
421 This option compiles in a table of x86 feature bits and corresponding
422 names. This is required to support /proc/cpuinfo and a few kernel
423 messages. You can disable this to save space, at the expense of
424 making those few kernel messages show numeric feature bits instead.
429 bool "Support x2apic"
430 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
432 This enables x2apic support on CPUs that have this feature.
434 This allows 32-bit apic IDs (so it can support very large systems),
435 and accesses the local apic via MSRs not via mmio.
437 If you don't know what to do here, say N.
440 bool "Enable MPS table" if ACPI || SFI
442 depends on X86_LOCAL_APIC
444 For old smp systems that do not have proper acpi support. Newer systems
445 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
449 depends on X86_GOLDFISH
452 bool "Avoid speculative indirect branches in kernel"
454 select STACK_VALIDATION if HAVE_STACK_VALIDATION
456 Compile kernel with the retpoline compiler options to guard against
457 kernel-to-user data leaks by avoiding speculative indirect
458 branches. Requires a compiler with -mindirect-branch=thunk-extern
459 support for full protection. The kernel may run slower.
461 config X86_CPU_RESCTRL
462 bool "x86 CPU resource control support"
463 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
465 select PROC_CPU_RESCTRL if PROC_FS
467 Enable x86 CPU resource control support.
469 Provide support for the allocation and monitoring of system resources
472 Intel calls this Intel Resource Director Technology
473 (Intel(R) RDT). More information about RDT can be found in the
474 Intel x86 Architecture Software Developer Manual.
476 AMD calls this AMD Platform Quality of Service (AMD QoS).
477 More information about AMD QoS can be found in the AMD64 Technology
478 Platform Quality of Service Extensions manual.
484 bool "Support for big SMP systems with more than 8 CPUs"
487 This option is needed for the systems that have more than 8 CPUs.
489 config X86_EXTENDED_PLATFORM
490 bool "Support for extended (non-PC) x86 platforms"
493 If you disable this option then the kernel will only support
494 standard PC platforms. (which covers the vast majority of
497 If you enable this option then you'll be able to select support
498 for the following (non-PC) 32 bit x86 platforms:
499 Goldfish (Android emulator)
502 SGI 320/540 (Visual Workstation)
503 STA2X11-based (e.g. Northville)
504 Moorestown MID devices
506 If you have one of these systems, or if you want to build a
507 generic distribution kernel, say Y here - otherwise say N.
511 config X86_EXTENDED_PLATFORM
512 bool "Support for extended (non-PC) x86 platforms"
515 If you disable this option then the kernel will only support
516 standard PC platforms. (which covers the vast majority of
519 If you enable this option then you'll be able to select support
520 for the following (non-PC) 64 bit x86 platforms:
525 If you have one of these systems, or if you want to build a
526 generic distribution kernel, say Y here - otherwise say N.
528 # This is an alphabetically sorted list of 64 bit extended platforms
529 # Please maintain the alphabetic order if and when there are additions
531 bool "Numascale NumaChip"
533 depends on X86_EXTENDED_PLATFORM
536 depends on X86_X2APIC
537 depends on PCI_MMCONFIG
539 Adds support for Numascale NumaChip large-SMP systems. Needed to
540 enable more than ~168 cores.
541 If you don't have one of these, you should say N here.
545 select HYPERVISOR_GUEST
547 depends on X86_64 && PCI
548 depends on X86_EXTENDED_PLATFORM
551 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
552 supposed to run on these EM64T-based machines. Only choose this option
553 if you have one of these machines.
556 bool "SGI Ultraviolet"
558 depends on X86_EXTENDED_PLATFORM
561 depends on X86_X2APIC
564 This option is needed in order to support SGI Ultraviolet systems.
565 If you don't have one of these, you should say N here.
567 # Following is an alphabetically sorted list of 32 bit extended platforms
568 # Please maintain the alphabetic order if and when there are additions
571 bool "Goldfish (Virtual Platform)"
572 depends on X86_EXTENDED_PLATFORM
574 Enable support for the Goldfish virtual platform used primarily
575 for Android development. Unless you are building for the Android
576 Goldfish emulator say N here.
579 bool "CE4100 TV platform"
581 depends on PCI_GODIRECT
582 depends on X86_IO_APIC
584 depends on X86_EXTENDED_PLATFORM
585 select X86_REBOOTFIXUPS
587 select OF_EARLY_FLATTREE
589 Select for the Intel CE media processor (CE4100) SOC.
590 This option compiles in support for the CE4100 SOC for settop
591 boxes and media devices.
594 bool "Intel MID platform support"
595 depends on X86_EXTENDED_PLATFORM
596 depends on X86_PLATFORM_DEVICES
598 depends on X86_64 || (PCI_GOANY && X86_32)
599 depends on X86_IO_APIC
605 select MFD_INTEL_MSIC
607 Select to build a kernel capable of supporting Intel MID (Mobile
608 Internet Device) platform systems which do not have the PCI legacy
609 interfaces. If you are building for a PC class system say N here.
611 Intel MID platforms are based on an Intel processor and chipset which
612 consume less power than most of the x86 derivatives.
614 config X86_INTEL_QUARK
615 bool "Intel Quark platform support"
617 depends on X86_EXTENDED_PLATFORM
618 depends on X86_PLATFORM_DEVICES
622 depends on X86_IO_APIC
627 Select to include support for Quark X1000 SoC.
628 Say Y here if you have a Quark based system such as the Arduino
629 compatible Intel Galileo.
631 config X86_INTEL_LPSS
632 bool "Intel Low Power Subsystem Support"
633 depends on X86 && ACPI && PCI
638 Select to build support for Intel Low Power Subsystem such as
639 found on Intel Lynxpoint PCH. Selecting this option enables
640 things like clock tree (common clock framework) and pincontrol
641 which are needed by the LPSS peripheral drivers.
643 config X86_AMD_PLATFORM_DEVICE
644 bool "AMD ACPI2Platform devices support"
649 Select to interpret AMD specific ACPI device to platform device
650 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
651 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
652 implemented under PINCTRL subsystem.
655 tristate "Intel SoC IOSF Sideband support for SoC platforms"
658 This option enables sideband register access support for Intel SoC
659 platforms. On these platforms the IOSF sideband is used in lieu of
660 MSR's for some register accesses, mostly but not limited to thermal
661 and power. Drivers may query the availability of this device to
662 determine if they need the sideband in order to work on these
663 platforms. The sideband is available on the following SoC products.
664 This list is not meant to be exclusive.
669 You should say Y if you are running a kernel on one of these SoC's.
671 config IOSF_MBI_DEBUG
672 bool "Enable IOSF sideband access through debugfs"
673 depends on IOSF_MBI && DEBUG_FS
675 Select this option to expose the IOSF sideband access registers (MCR,
676 MDR, MCRX) through debugfs to write and read register information from
677 different units on the SoC. This is most useful for obtaining device
678 state information for debug and analysis. As this is a general access
679 mechanism, users of this option would have specific knowledge of the
680 device they want to access.
682 If you don't require the option or are in doubt, say N.
685 bool "RDC R-321x SoC"
687 depends on X86_EXTENDED_PLATFORM
689 select X86_REBOOTFIXUPS
691 This option is needed for RDC R-321x system-on-chip, also known
693 If you don't have one of these chips, you should say N here.
695 config X86_32_NON_STANDARD
696 bool "Support non-standard 32-bit SMP architectures"
697 depends on X86_32 && SMP
698 depends on X86_EXTENDED_PLATFORM
700 This option compiles in the bigsmp and STA2X11 default
701 subarchitectures. It is intended for a generic binary
702 kernel. If you select them all, kernel will probe it one by
703 one and will fallback to default.
705 # Alphabetically sorted list of Non standard 32 bit platforms
707 config X86_SUPPORTS_MEMORY_FAILURE
709 # MCE code calls memory_failure():
711 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
712 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
713 depends on X86_64 || !SPARSEMEM
714 select ARCH_SUPPORTS_MEMORY_FAILURE
717 bool "STA2X11 Companion Chip Support"
718 depends on X86_32_NON_STANDARD && PCI
723 This adds support for boards based on the STA2X11 IO-Hub,
724 a.k.a. "ConneXt". The chip is used in place of the standard
725 PC chipset, so all "standard" peripherals are missing. If this
726 option is selected the kernel will still be able to boot on
727 standard PC machines.
730 tristate "Eurobraille/Iris poweroff module"
733 The Iris machines from EuroBraille do not have APM or ACPI support
734 to shut themselves down properly. A special I/O sequence is
735 needed to do so, which is what this module does at
738 This is only for Iris machines from EuroBraille.
742 config SCHED_OMIT_FRAME_POINTER
744 prompt "Single-depth WCHAN output"
747 Calculate simpler /proc/<PID>/wchan values. If this option
748 is disabled then wchan values will recurse back to the
749 caller function. This provides more accurate wchan values,
750 at the expense of slightly more scheduling overhead.
752 If in doubt, say "Y".
754 menuconfig HYPERVISOR_GUEST
755 bool "Linux guest support"
757 Say Y here to enable options for running Linux under various hyper-
758 visors. This option enables basic hypervisor detection and platform
761 If you say N, all options in this submenu will be skipped and
762 disabled, and Linux guest support won't be built in.
767 bool "Enable paravirtualization code"
769 This changes the kernel so it can modify itself when it is run
770 under a hypervisor, potentially improving performance significantly
771 over full virtualization. However, when run without a hypervisor
772 the kernel is theoretically slower and slightly larger.
777 config PARAVIRT_DEBUG
778 bool "paravirt-ops debugging"
779 depends on PARAVIRT && DEBUG_KERNEL
781 Enable to debug paravirt_ops internals. Specifically, BUG if
782 a paravirt_op is missing when it is called.
784 config PARAVIRT_SPINLOCKS
785 bool "Paravirtualization layer for spinlocks"
786 depends on PARAVIRT && SMP
788 Paravirtualized spinlocks allow a pvops backend to replace the
789 spinlock implementation with something virtualization-friendly
790 (for example, block the virtual CPU rather than spinning).
792 It has a minimal impact on native kernels and gives a nice performance
793 benefit on paravirtualized KVM / Xen kernels.
795 If you are unsure how to answer this question, answer Y.
797 config X86_HV_CALLBACK_VECTOR
800 source "arch/x86/xen/Kconfig"
803 bool "KVM Guest support (including kvmclock)"
805 select PARAVIRT_CLOCK
806 select ARCH_CPUIDLE_HALTPOLL
807 select X86_HV_CALLBACK_VECTOR
810 This option enables various optimizations for running under the KVM
811 hypervisor. It includes a paravirtualized clock, so that instead
812 of relying on a PIT (or probably other) emulation by the
813 underlying device model, the host provides the guest with
814 timing infrastructure such as time of day, and system time
816 config ARCH_CPUIDLE_HALTPOLL
818 prompt "Disable host haltpoll when loading haltpoll driver"
820 If virtualized under KVM, disable host haltpoll.
823 bool "Support for running PVH guests"
825 This option enables the PVH entry point for guest virtual machines
826 as specified in the x86/HVM direct boot ABI.
828 config PARAVIRT_TIME_ACCOUNTING
829 bool "Paravirtual steal time accounting"
832 Select this option to enable fine granularity task steal time
833 accounting. Time spent executing other tasks in parallel with
834 the current vCPU is discounted from the vCPU power. To account for
835 that, there can be a small performance impact.
837 If in doubt, say N here.
839 config PARAVIRT_CLOCK
842 config JAILHOUSE_GUEST
843 bool "Jailhouse non-root cell support"
844 depends on X86_64 && PCI
847 This option allows to run Linux as guest in a Jailhouse non-root
848 cell. You can leave this option disabled if you only want to start
849 Jailhouse and run Linux afterwards in the root cell.
852 bool "ACRN Guest support"
854 select X86_HV_CALLBACK_VECTOR
856 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
857 a flexible, lightweight reference open-source hypervisor, built with
858 real-time and safety-criticality in mind. It is built for embedded
859 IOT with small footprint and real-time features. More details can be
860 found in https://projectacrn.org/.
862 endif #HYPERVISOR_GUEST
864 source "arch/x86/Kconfig.cpu"
868 prompt "HPET Timer Support" if X86_32
870 Use the IA-PC HPET (High Precision Event Timer) to manage
871 time in preference to the PIT and RTC, if a HPET is
873 HPET is the next generation timer replacing legacy 8254s.
874 The HPET provides a stable time base on SMP
875 systems, unlike the TSC, but it is more expensive to access,
876 as it is off-chip. The interface used is documented
877 in the HPET spec, revision 1.
879 You can safely choose Y here. However, HPET will only be
880 activated if the platform and the BIOS support this feature.
881 Otherwise the 8254 will be used for timing services.
883 Choose N to continue using the legacy 8254 timer.
885 config HPET_EMULATE_RTC
887 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
890 def_bool y if X86_INTEL_MID
891 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
893 depends on X86_INTEL_MID && SFI
895 APB timer is the replacement for 8254, HPET on X86 MID platforms.
896 The APBT provides a stable time base on SMP
897 systems, unlike the TSC, but it is more expensive to access,
898 as it is off-chip. APB timers are always running regardless of CPU
899 C states, they are used as per CPU clockevent device when possible.
901 # Mark as expert because too many people got it wrong.
902 # The code disables itself when not needed.
905 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
906 bool "Enable DMI scanning" if EXPERT
908 Enabled scanning of DMI to identify machine quirks. Say Y
909 here unless you have verified that your setup is not
910 affected by entries in the DMI blacklist. Required by PNP
914 bool "Old AMD GART IOMMU support"
918 depends on X86_64 && PCI && AMD_NB
920 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
921 GART based hardware IOMMUs.
923 The GART supports full DMA access for devices with 32-bit access
924 limitations, on systems with more than 3 GB. This is usually needed
925 for USB, sound, many IDE/SATA chipsets and some other devices.
927 Newer systems typically have a modern AMD IOMMU, supported via
928 the CONFIG_AMD_IOMMU=y config option.
930 In normal configurations this driver is only active when needed:
931 there's more than 3 GB of memory and the system contains a
932 32-bit limited device.
937 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
938 depends on X86_64 && SMP && DEBUG_KERNEL
939 select CPUMASK_OFFSTACK
941 Enable maximum number of CPUS and NUMA Nodes for this architecture.
945 # The maximum number of CPUs supported:
947 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
948 # and which can be configured interactively in the
949 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
951 # The ranges are different on 32-bit and 64-bit kernels, depending on
952 # hardware capabilities and scalability features of the kernel.
954 # ( If MAXSMP is enabled we just use the highest possible value and disable
955 # interactive configuration. )
958 config NR_CPUS_RANGE_BEGIN
960 default NR_CPUS_RANGE_END if MAXSMP
964 config NR_CPUS_RANGE_END
967 default 64 if SMP && X86_BIGSMP
968 default 8 if SMP && !X86_BIGSMP
971 config NR_CPUS_RANGE_END
974 default 8192 if SMP && CPUMASK_OFFSTACK
975 default 512 if SMP && !CPUMASK_OFFSTACK
978 config NR_CPUS_DEFAULT
981 default 32 if X86_BIGSMP
985 config NR_CPUS_DEFAULT
988 default 8192 if MAXSMP
993 int "Maximum number of CPUs" if SMP && !MAXSMP
994 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
995 default NR_CPUS_DEFAULT
997 This allows you to specify the maximum number of CPUs which this
998 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
999 supported value is 8192, otherwise the maximum value is 512. The
1000 minimum value which makes sense is 2.
1002 This is purely to save memory: each supported CPU adds about 8KB
1003 to the kernel image.
1010 prompt "Multi-core scheduler support"
1013 Multi-core scheduler support improves the CPU scheduler's decision
1014 making when dealing with multi-core CPU chips at a cost of slightly
1015 increased overhead in some places. If unsure say N here.
1017 config SCHED_MC_PRIO
1018 bool "CPU core priorities scheduler support"
1019 depends on SCHED_MC && CPU_SUP_INTEL
1020 select X86_INTEL_PSTATE
1024 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1025 core ordering determined at manufacturing time, which allows
1026 certain cores to reach higher turbo frequencies (when running
1027 single threaded workloads) than others.
1029 Enabling this kernel feature teaches the scheduler about
1030 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1031 scheduler's CPU selection logic accordingly, so that higher
1032 overall system performance can be achieved.
1034 This feature will have no effect on CPUs without this feature.
1036 If unsure say Y here.
1040 depends on !SMP && X86_LOCAL_APIC
1043 bool "Local APIC support on uniprocessors" if !PCI_MSI
1045 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1047 A local APIC (Advanced Programmable Interrupt Controller) is an
1048 integrated interrupt controller in the CPU. If you have a single-CPU
1049 system which has a processor with a local APIC, you can say Y here to
1050 enable and use it. If you say Y here even though your machine doesn't
1051 have a local APIC, then the kernel will still run with no slowdown at
1052 all. The local APIC supports CPU-generated self-interrupts (timer,
1053 performance counters), and the NMI watchdog which detects hard
1056 config X86_UP_IOAPIC
1057 bool "IO-APIC support on uniprocessors"
1058 depends on X86_UP_APIC
1060 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1061 SMP-capable replacement for PC-style interrupt controllers. Most
1062 SMP systems and many recent uniprocessor systems have one.
1064 If you have a single-CPU system with an IO-APIC, you can say Y here
1065 to use it. If you say Y here even though your machine doesn't have
1066 an IO-APIC, then the kernel will still run with no slowdown at all.
1068 config X86_LOCAL_APIC
1070 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1071 select IRQ_DOMAIN_HIERARCHY
1072 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1076 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1078 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1079 bool "Reroute for broken boot IRQs"
1080 depends on X86_IO_APIC
1082 This option enables a workaround that fixes a source of
1083 spurious interrupts. This is recommended when threaded
1084 interrupt handling is used on systems where the generation of
1085 superfluous "boot interrupts" cannot be disabled.
1087 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1088 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1089 kernel does during interrupt handling). On chipsets where this
1090 boot IRQ generation cannot be disabled, this workaround keeps
1091 the original IRQ line masked so that only the equivalent "boot
1092 IRQ" is delivered to the CPUs. The workaround also tells the
1093 kernel to set up the IRQ handler on the boot IRQ line. In this
1094 way only one interrupt is delivered to the kernel. Otherwise
1095 the spurious second interrupt may cause the kernel to bring
1096 down (vital) interrupt lines.
1098 Only affects "broken" chipsets. Interrupt sharing may be
1099 increased on these systems.
1102 bool "Machine Check / overheating reporting"
1103 select GENERIC_ALLOCATOR
1106 Machine Check support allows the processor to notify the
1107 kernel if it detects a problem (e.g. overheating, data corruption).
1108 The action the kernel takes depends on the severity of the problem,
1109 ranging from warning messages to halting the machine.
1111 config X86_MCELOG_LEGACY
1112 bool "Support for deprecated /dev/mcelog character device"
1115 Enable support for /dev/mcelog which is needed by the old mcelog
1116 userspace logging daemon. Consider switching to the new generation
1119 config X86_MCE_INTEL
1121 prompt "Intel MCE features"
1122 depends on X86_MCE && X86_LOCAL_APIC
1124 Additional support for intel specific MCE features such as
1125 the thermal monitor.
1129 prompt "AMD MCE features"
1130 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1132 Additional support for AMD specific MCE features such as
1133 the DRAM Error Threshold.
1135 config X86_ANCIENT_MCE
1136 bool "Support for old Pentium 5 / WinChip machine checks"
1137 depends on X86_32 && X86_MCE
1139 Include support for machine check handling on old Pentium 5 or WinChip
1140 systems. These typically need to be enabled explicitly on the command
1143 config X86_MCE_THRESHOLD
1144 depends on X86_MCE_AMD || X86_MCE_INTEL
1147 config X86_MCE_INJECT
1148 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1149 tristate "Machine check injector support"
1151 Provide support for injecting machine checks for testing purposes.
1152 If you don't know what a machine check is and you don't do kernel
1153 QA it is safe to say n.
1155 config X86_THERMAL_VECTOR
1157 depends on X86_MCE_INTEL
1159 source "arch/x86/events/Kconfig"
1161 config X86_LEGACY_VM86
1162 bool "Legacy VM86 support"
1165 This option allows user programs to put the CPU into V8086
1166 mode, which is an 80286-era approximation of 16-bit real mode.
1168 Some very old versions of X and/or vbetool require this option
1169 for user mode setting. Similarly, DOSEMU will use it if
1170 available to accelerate real mode DOS programs. However, any
1171 recent version of DOSEMU, X, or vbetool should be fully
1172 functional even without kernel VM86 support, as they will all
1173 fall back to software emulation. Nevertheless, if you are using
1174 a 16-bit DOS program where 16-bit performance matters, vm86
1175 mode might be faster than emulation and you might want to
1178 Note that any app that works on a 64-bit kernel is unlikely to
1179 need this option, as 64-bit kernels don't, and can't, support
1180 V8086 mode. This option is also unrelated to 16-bit protected
1181 mode and is not needed to run most 16-bit programs under Wine.
1183 Enabling this option increases the complexity of the kernel
1184 and slows down exception handling a tiny bit.
1186 If unsure, say N here.
1190 default X86_LEGACY_VM86
1193 bool "Enable support for 16-bit segments" if EXPERT
1195 depends on MODIFY_LDT_SYSCALL
1197 This option is required by programs like Wine to run 16-bit
1198 protected mode legacy code on x86 processors. Disabling
1199 this option saves about 300 bytes on i386, or around 6K text
1200 plus 16K runtime memory on x86-64,
1204 depends on X86_16BIT && X86_32
1208 depends on X86_16BIT && X86_64
1210 config X86_VSYSCALL_EMULATION
1211 bool "Enable vsyscall emulation" if EXPERT
1215 This enables emulation of the legacy vsyscall page. Disabling
1216 it is roughly equivalent to booting with vsyscall=none, except
1217 that it will also disable the helpful warning if a program
1218 tries to use a vsyscall. With this option set to N, offending
1219 programs will just segfault, citing addresses of the form
1222 This option is required by many programs built before 2013, and
1223 care should be used even with newer programs if set to N.
1225 Disabling this option saves about 7K of kernel size and
1226 possibly 4K of additional runtime pagetable memory.
1228 config X86_IOPL_IOPERM
1229 bool "IOPERM and IOPL Emulation"
1232 This enables the ioperm() and iopl() syscalls which are necessary
1233 for legacy applications.
1235 Legacy IOPL support is an overbroad mechanism which allows user
1236 space aside of accessing all 65536 I/O ports also to disable
1237 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1238 capabilities and permission from potentially active security
1241 The emulation restricts the functionality of the syscall to
1242 only allowing the full range I/O port access, but prevents the
1243 ability to disable interrupts from user space which would be
1244 granted if the hardware IOPL mechanism would be used.
1247 tristate "Toshiba Laptop support"
1250 This adds a driver to safely access the System Management Mode of
1251 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1252 not work on models with a Phoenix BIOS. The System Management Mode
1253 is used to set the BIOS and power saving options on Toshiba portables.
1255 For information on utilities to make use of this driver see the
1256 Toshiba Linux utilities web site at:
1257 <http://www.buzzard.org.uk/toshiba/>.
1259 Say Y if you intend to run this kernel on a Toshiba portable.
1263 tristate "Dell i8k legacy laptop support"
1265 select SENSORS_DELL_SMM
1267 This option enables legacy /proc/i8k userspace interface in hwmon
1268 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1269 temperature and allows controlling fan speeds of Dell laptops via
1270 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1271 it reports also power and hotkey status. For fan speed control is
1272 needed userspace package i8kutils.
1274 Say Y if you intend to run this kernel on old Dell laptops or want to
1275 use userspace package i8kutils.
1278 config X86_REBOOTFIXUPS
1279 bool "Enable X86 board specific fixups for reboot"
1282 This enables chipset and/or board specific fixups to be done
1283 in order to get reboot to work correctly. This is only needed on
1284 some combinations of hardware and BIOS. The symptom, for which
1285 this config is intended, is when reboot ends with a stalled/hung
1288 Currently, the only fixup is for the Geode machines using
1289 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1291 Say Y if you want to enable the fixup. Currently, it's safe to
1292 enable this option even if you don't need it.
1296 bool "CPU microcode loading support"
1298 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1300 If you say Y here, you will be able to update the microcode on
1301 Intel and AMD processors. The Intel support is for the IA32 family,
1302 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1303 AMD support is for families 0x10 and later. You will obviously need
1304 the actual microcode binary data itself which is not shipped with
1307 The preferred method to load microcode from a detached initrd is described
1308 in Documentation/x86/microcode.rst. For that you need to enable
1309 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1310 initrd for microcode blobs.
1312 In addition, you can build the microcode into the kernel. For that you
1313 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1316 config MICROCODE_INTEL
1317 bool "Intel microcode loading support"
1318 depends on MICROCODE
1321 This options enables microcode patch loading support for Intel
1324 For the current Intel microcode data package go to
1325 <https://downloadcenter.intel.com> and search for
1326 'Linux Processor Microcode Data File'.
1328 config MICROCODE_AMD
1329 bool "AMD microcode loading support"
1330 depends on MICROCODE
1332 If you select this option, microcode patch loading support for AMD
1333 processors will be enabled.
1335 config MICROCODE_OLD_INTERFACE
1336 bool "Ancient loading interface (DEPRECATED)"
1338 depends on MICROCODE
1340 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1341 which was used by userspace tools like iucode_tool and microcode.ctl.
1342 It is inadequate because it runs too late to be able to properly
1343 load microcode on a machine and it needs special tools. Instead, you
1344 should've switched to the early loading method with the initrd or
1345 builtin microcode by now: Documentation/x86/microcode.rst
1348 tristate "/dev/cpu/*/msr - Model-specific register support"
1350 This device gives privileged processes access to the x86
1351 Model-Specific Registers (MSRs). It is a character device with
1352 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1353 MSR accesses are directed to a specific CPU on multi-processor
1357 tristate "/dev/cpu/*/cpuid - CPU information support"
1359 This device gives processes access to the x86 CPUID instruction to
1360 be executed on a specific processor. It is a character device
1361 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1365 prompt "High Memory Support"
1372 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1373 However, the address space of 32-bit x86 processors is only 4
1374 Gigabytes large. That means that, if you have a large amount of
1375 physical memory, not all of it can be "permanently mapped" by the
1376 kernel. The physical memory that's not permanently mapped is called
1379 If you are compiling a kernel which will never run on a machine with
1380 more than 1 Gigabyte total physical RAM, answer "off" here (default
1381 choice and suitable for most users). This will result in a "3GB/1GB"
1382 split: 3GB are mapped so that each process sees a 3GB virtual memory
1383 space and the remaining part of the 4GB virtual memory space is used
1384 by the kernel to permanently map as much physical memory as
1387 If the machine has between 1 and 4 Gigabytes physical RAM, then
1390 If more than 4 Gigabytes is used then answer "64GB" here. This
1391 selection turns Intel PAE (Physical Address Extension) mode on.
1392 PAE implements 3-level paging on IA32 processors. PAE is fully
1393 supported by Linux, PAE mode is implemented on all recent Intel
1394 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1395 then the kernel will not boot on CPUs that don't support PAE!
1397 The actual amount of total physical memory will either be
1398 auto detected or can be forced by using a kernel command line option
1399 such as "mem=256M". (Try "man bootparam" or see the documentation of
1400 your boot loader (lilo or loadlin) about how to pass options to the
1401 kernel at boot time.)
1403 If unsure, say "off".
1408 Select this if you have a 32-bit processor and between 1 and 4
1409 gigabytes of physical RAM.
1413 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1416 Select this if you have a 32-bit processor and more than 4
1417 gigabytes of physical RAM.
1422 prompt "Memory split" if EXPERT
1426 Select the desired split between kernel and user memory.
1428 If the address range available to the kernel is less than the
1429 physical memory installed, the remaining memory will be available
1430 as "high memory". Accessing high memory is a little more costly
1431 than low memory, as it needs to be mapped into the kernel first.
1432 Note that increasing the kernel address space limits the range
1433 available to user programs, making the address space there
1434 tighter. Selecting anything other than the default 3G/1G split
1435 will also likely make your kernel incompatible with binary-only
1438 If you are not absolutely sure what you are doing, leave this
1442 bool "3G/1G user/kernel split"
1443 config VMSPLIT_3G_OPT
1445 bool "3G/1G user/kernel split (for full 1G low memory)"
1447 bool "2G/2G user/kernel split"
1448 config VMSPLIT_2G_OPT
1450 bool "2G/2G user/kernel split (for full 2G low memory)"
1452 bool "1G/3G user/kernel split"
1457 default 0xB0000000 if VMSPLIT_3G_OPT
1458 default 0x80000000 if VMSPLIT_2G
1459 default 0x78000000 if VMSPLIT_2G_OPT
1460 default 0x40000000 if VMSPLIT_1G
1466 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1469 bool "PAE (Physical Address Extension) Support"
1470 depends on X86_32 && !HIGHMEM4G
1471 select PHYS_ADDR_T_64BIT
1474 PAE is required for NX support, and furthermore enables
1475 larger swapspace support for non-overcommit purposes. It
1476 has the cost of more pagetable lookup overhead, and also
1477 consumes more pagetable space per process.
1480 bool "Enable 5-level page tables support"
1482 select DYNAMIC_MEMORY_LAYOUT
1483 select SPARSEMEM_VMEMMAP
1486 5-level paging enables access to larger address space:
1487 upto 128 PiB of virtual address space and 4 PiB of
1488 physical address space.
1490 It will be supported by future Intel CPUs.
1492 A kernel with the option enabled can be booted on machines that
1493 support 4- or 5-level paging.
1495 See Documentation/x86/x86_64/5level-paging.rst for more
1500 config X86_DIRECT_GBPAGES
1504 Certain kernel features effectively disable kernel
1505 linear 1 GB mappings (even if the CPU otherwise
1506 supports them), so don't confuse the user by printing
1507 that we have them enabled.
1509 config X86_CPA_STATISTICS
1510 bool "Enable statistic for Change Page Attribute"
1513 Expose statistics about the Change Page Attribute mechanism, which
1514 helps to determine the effectiveness of preserving large and huge
1515 page mappings when mapping protections are changed.
1517 config AMD_MEM_ENCRYPT
1518 bool "AMD Secure Memory Encryption (SME) support"
1519 depends on X86_64 && CPU_SUP_AMD
1520 select DMA_COHERENT_POOL
1521 select DYNAMIC_PHYSICAL_MASK
1522 select ARCH_USE_MEMREMAP_PROT
1523 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1525 Say yes to enable support for the encryption of system memory.
1526 This requires an AMD processor that supports Secure Memory
1529 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1530 bool "Activate AMD Secure Memory Encryption (SME) by default"
1532 depends on AMD_MEM_ENCRYPT
1534 Say yes to have system memory encrypted by default if running on
1535 an AMD processor that supports Secure Memory Encryption (SME).
1537 If set to Y, then the encryption of system memory can be
1538 deactivated with the mem_encrypt=off command line option.
1540 If set to N, then the encryption of system memory can be
1541 activated with the mem_encrypt=on command line option.
1543 # Common NUMA Features
1545 bool "NUMA Memory Allocation and Scheduler Support"
1547 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1548 default y if X86_BIGSMP
1550 Enable NUMA (Non-Uniform Memory Access) support.
1552 The kernel will try to allocate memory used by a CPU on the
1553 local memory controller of the CPU and add some more
1554 NUMA awareness to the kernel.
1556 For 64-bit this is recommended if the system is Intel Core i7
1557 (or later), AMD Opteron, or EM64T NUMA.
1559 For 32-bit this is only needed if you boot a 32-bit
1560 kernel on a 64-bit NUMA platform.
1562 Otherwise, you should say N.
1566 prompt "Old style AMD Opteron NUMA detection"
1567 depends on X86_64 && NUMA && PCI
1569 Enable AMD NUMA node topology detection. You should say Y here if
1570 you have a multi processor AMD system. This uses an old method to
1571 read the NUMA configuration directly from the builtin Northbridge
1572 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1573 which also takes priority if both are compiled in.
1575 config X86_64_ACPI_NUMA
1577 prompt "ACPI NUMA detection"
1578 depends on X86_64 && NUMA && ACPI && PCI
1581 Enable ACPI SRAT based node topology detection.
1584 bool "NUMA emulation"
1587 Enable NUMA emulation. A flat machine will be split
1588 into virtual nodes when booted with "numa=fake=N", where N is the
1589 number of nodes. This is only useful for debugging.
1592 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1594 default "10" if MAXSMP
1595 default "6" if X86_64
1597 depends on NEED_MULTIPLE_NODES
1599 Specify the maximum number of NUMA Nodes available on the target
1600 system. Increases memory reserved to accommodate various tables.
1602 config ARCH_FLATMEM_ENABLE
1604 depends on X86_32 && !NUMA
1606 config ARCH_SPARSEMEM_ENABLE
1608 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1609 select SPARSEMEM_STATIC if X86_32
1610 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1612 config ARCH_SPARSEMEM_DEFAULT
1613 def_bool X86_64 || (NUMA && X86_32)
1615 config ARCH_SELECT_MEMORY_MODEL
1617 depends on ARCH_SPARSEMEM_ENABLE
1619 config ARCH_MEMORY_PROBE
1620 bool "Enable sysfs memory/probe interface"
1621 depends on X86_64 && MEMORY_HOTPLUG
1623 This option enables a sysfs memory/probe interface for testing.
1624 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1625 If you are unsure how to answer this question, answer N.
1627 config ARCH_PROC_KCORE_TEXT
1629 depends on X86_64 && PROC_KCORE
1631 config ILLEGAL_POINTER_VALUE
1634 default 0xdead000000000000 if X86_64
1636 config X86_PMEM_LEGACY_DEVICE
1639 config X86_PMEM_LEGACY
1640 tristate "Support non-standard NVDIMMs and ADR protected memory"
1641 depends on PHYS_ADDR_T_64BIT
1643 select X86_PMEM_LEGACY_DEVICE
1644 select NUMA_KEEP_MEMINFO if NUMA
1647 Treat memory marked using the non-standard e820 type of 12 as used
1648 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1649 The kernel will offer these regions to the 'pmem' driver so
1650 they can be used for persistent storage.
1655 bool "Allocate 3rd-level pagetables from highmem"
1658 The VM uses one page table entry for each page of physical memory.
1659 For systems with a lot of RAM, this can be wasteful of precious
1660 low memory. Setting this option will put user-space page table
1661 entries in high memory.
1663 config X86_CHECK_BIOS_CORRUPTION
1664 bool "Check for low memory corruption"
1666 Periodically check for memory corruption in low memory, which
1667 is suspected to be caused by BIOS. Even when enabled in the
1668 configuration, it is disabled at runtime. Enable it by
1669 setting "memory_corruption_check=1" on the kernel command
1670 line. By default it scans the low 64k of memory every 60
1671 seconds; see the memory_corruption_check_size and
1672 memory_corruption_check_period parameters in
1673 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1675 When enabled with the default parameters, this option has
1676 almost no overhead, as it reserves a relatively small amount
1677 of memory and scans it infrequently. It both detects corruption
1678 and prevents it from affecting the running system.
1680 It is, however, intended as a diagnostic tool; if repeatable
1681 BIOS-originated corruption always affects the same memory,
1682 you can use memmap= to prevent the kernel from using that
1685 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1686 bool "Set the default setting of memory_corruption_check"
1687 depends on X86_CHECK_BIOS_CORRUPTION
1690 Set whether the default state of memory_corruption_check is
1693 config X86_RESERVE_LOW
1694 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1698 Specify the amount of low memory to reserve for the BIOS.
1700 The first page contains BIOS data structures that the kernel
1701 must not use, so that page must always be reserved.
1703 By default we reserve the first 64K of physical RAM, as a
1704 number of BIOSes are known to corrupt that memory range
1705 during events such as suspend/resume or monitor cable
1706 insertion, so it must not be used by the kernel.
1708 You can set this to 4 if you are absolutely sure that you
1709 trust the BIOS to get all its memory reservations and usages
1710 right. If you know your BIOS have problems beyond the
1711 default 64K area, you can set this to 640 to avoid using the
1712 entire low memory range.
1714 If you have doubts about the BIOS (e.g. suspend/resume does
1715 not work or there's kernel crashes after certain hardware
1716 hotplug events) then you might want to enable
1717 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1718 typical corruption patterns.
1720 Leave this to the default value of 64 if you are unsure.
1722 config MATH_EMULATION
1724 depends on MODIFY_LDT_SYSCALL
1725 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1727 Linux can emulate a math coprocessor (used for floating point
1728 operations) if you don't have one. 486DX and Pentium processors have
1729 a math coprocessor built in, 486SX and 386 do not, unless you added
1730 a 487DX or 387, respectively. (The messages during boot time can
1731 give you some hints here ["man dmesg"].) Everyone needs either a
1732 coprocessor or this emulation.
1734 If you don't have a math coprocessor, you need to say Y here; if you
1735 say Y here even though you have a coprocessor, the coprocessor will
1736 be used nevertheless. (This behavior can be changed with the kernel
1737 command line option "no387", which comes handy if your coprocessor
1738 is broken. Try "man bootparam" or see the documentation of your boot
1739 loader (lilo or loadlin) about how to pass options to the kernel at
1740 boot time.) This means that it is a good idea to say Y here if you
1741 intend to use this kernel on different machines.
1743 More information about the internals of the Linux math coprocessor
1744 emulation can be found in <file:arch/x86/math-emu/README>.
1746 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1747 kernel, it won't hurt.
1751 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1753 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1754 the Memory Type Range Registers (MTRRs) may be used to control
1755 processor access to memory ranges. This is most useful if you have
1756 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1757 allows bus write transfers to be combined into a larger transfer
1758 before bursting over the PCI/AGP bus. This can increase performance
1759 of image write operations 2.5 times or more. Saying Y here creates a
1760 /proc/mtrr file which may be used to manipulate your processor's
1761 MTRRs. Typically the X server should use this.
1763 This code has a reasonably generic interface so that similar
1764 control registers on other processors can be easily supported
1767 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1768 Registers (ARRs) which provide a similar functionality to MTRRs. For
1769 these, the ARRs are used to emulate the MTRRs.
1770 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1771 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1772 write-combining. All of these processors are supported by this code
1773 and it makes sense to say Y here if you have one of them.
1775 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1776 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1777 can lead to all sorts of problems, so it's good to say Y here.
1779 You can safely say Y even if your machine doesn't have MTRRs, you'll
1780 just add about 9 KB to your kernel.
1782 See <file:Documentation/x86/mtrr.rst> for more information.
1784 config MTRR_SANITIZER
1786 prompt "MTRR cleanup support"
1789 Convert MTRR layout from continuous to discrete, so X drivers can
1790 add writeback entries.
1792 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1793 The largest mtrr entry size for a continuous block can be set with
1798 config MTRR_SANITIZER_ENABLE_DEFAULT
1799 int "MTRR cleanup enable value (0-1)"
1802 depends on MTRR_SANITIZER
1804 Enable mtrr cleanup default value
1806 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1807 int "MTRR cleanup spare reg num (0-7)"
1810 depends on MTRR_SANITIZER
1812 mtrr cleanup spare entries default, it can be changed via
1813 mtrr_spare_reg_nr=N on the kernel command line.
1817 prompt "x86 PAT support" if EXPERT
1820 Use PAT attributes to setup page level cache control.
1822 PATs are the modern equivalents of MTRRs and are much more
1823 flexible than MTRRs.
1825 Say N here if you see bootup problems (boot crash, boot hang,
1826 spontaneous reboots) or a non-working video driver.
1830 config ARCH_USES_PG_UNCACHED
1836 prompt "x86 architectural random number generator" if EXPERT
1838 Enable the x86 architectural RDRAND instruction
1839 (Intel Bull Mountain technology) to generate random numbers.
1840 If supported, this is a high bandwidth, cryptographically
1841 secure hardware random number generator.
1845 prompt "Supervisor Mode Access Prevention" if EXPERT
1847 Supervisor Mode Access Prevention (SMAP) is a security
1848 feature in newer Intel processors. There is a small
1849 performance cost if this enabled and turned on; there is
1850 also a small increase in the kernel size if this is enabled.
1856 prompt "User Mode Instruction Prevention" if EXPERT
1858 User Mode Instruction Prevention (UMIP) is a security feature in
1859 some x86 processors. If enabled, a general protection fault is
1860 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1861 executed in user mode. These instructions unnecessarily expose
1862 information about the hardware state.
1864 The vast majority of applications do not use these instructions.
1865 For the very few that do, software emulation is provided in
1866 specific cases in protected and virtual-8086 modes. Emulated
1869 config X86_INTEL_MEMORY_PROTECTION_KEYS
1870 prompt "Memory Protection Keys"
1872 # Note: only available in 64-bit mode
1873 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1874 select ARCH_USES_HIGH_VMA_FLAGS
1875 select ARCH_HAS_PKEYS
1877 Memory Protection Keys provides a mechanism for enforcing
1878 page-based protections, but without requiring modification of the
1879 page tables when an application changes protection domains.
1881 For details, see Documentation/core-api/protection-keys.rst
1886 prompt "TSX enable mode"
1887 depends on CPU_SUP_INTEL
1888 default X86_INTEL_TSX_MODE_OFF
1890 Intel's TSX (Transactional Synchronization Extensions) feature
1891 allows to optimize locking protocols through lock elision which
1892 can lead to a noticeable performance boost.
1894 On the other hand it has been shown that TSX can be exploited
1895 to form side channel attacks (e.g. TAA) and chances are there
1896 will be more of those attacks discovered in the future.
1898 Therefore TSX is not enabled by default (aka tsx=off). An admin
1899 might override this decision by tsx=on the command line parameter.
1900 Even with TSX enabled, the kernel will attempt to enable the best
1901 possible TAA mitigation setting depending on the microcode available
1902 for the particular machine.
1904 This option allows to set the default tsx mode between tsx=on, =off
1905 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1908 Say off if not sure, auto if TSX is in use but it should be used on safe
1909 platforms or on if TSX is in use and the security aspect of tsx is not
1912 config X86_INTEL_TSX_MODE_OFF
1915 TSX is disabled if possible - equals to tsx=off command line parameter.
1917 config X86_INTEL_TSX_MODE_ON
1920 TSX is always enabled on TSX capable HW - equals the tsx=on command
1923 config X86_INTEL_TSX_MODE_AUTO
1926 TSX is enabled on TSX capable HW that is believed to be safe against
1927 side channel attacks- equals the tsx=auto command line parameter.
1931 bool "EFI runtime service support"
1934 select EFI_RUNTIME_WRAPPERS
1936 This enables the kernel to use EFI runtime services that are
1937 available (such as the EFI variable services).
1939 This option is only useful on systems that have EFI firmware.
1940 In addition, you should use the latest ELILO loader available
1941 at <http://elilo.sourceforge.net> in order to take advantage
1942 of EFI runtime services. However, even with this option, the
1943 resultant kernel should continue to boot on existing non-EFI
1947 bool "EFI stub support"
1948 depends on EFI && !X86_USE_3DNOW
1949 depends on $(cc-option,-mabi=ms) || X86_32
1952 This kernel feature allows a bzImage to be loaded directly
1953 by EFI firmware without the use of a bootloader.
1955 See Documentation/admin-guide/efi-stub.rst for more information.
1958 bool "EFI mixed-mode support"
1959 depends on EFI_STUB && X86_64
1961 Enabling this feature allows a 64-bit kernel to be booted
1962 on a 32-bit firmware, provided that your CPU supports 64-bit
1965 Note that it is not possible to boot a mixed-mode enabled
1966 kernel via the EFI boot stub - a bootloader that supports
1967 the EFI handover protocol must be used.
1973 prompt "Enable seccomp to safely compute untrusted bytecode"
1975 This kernel feature is useful for number crunching applications
1976 that may need to compute untrusted bytecode during their
1977 execution. By using pipes or other transports made available to
1978 the process as file descriptors supporting the read/write
1979 syscalls, it's possible to isolate those applications in
1980 their own address space using seccomp. Once seccomp is
1981 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1982 and the task is only allowed to execute a few safe syscalls
1983 defined by each seccomp mode.
1985 If unsure, say Y. Only embedded should say N here.
1987 source "kernel/Kconfig.hz"
1990 bool "kexec system call"
1993 kexec is a system call that implements the ability to shutdown your
1994 current kernel, and to start another kernel. It is like a reboot
1995 but it is independent of the system firmware. And like a reboot
1996 you can start any kernel with it, not just Linux.
1998 The name comes from the similarity to the exec system call.
2000 It is an ongoing process to be certain the hardware in a machine
2001 is properly shutdown, so do not be surprised if this code does not
2002 initially work for you. As of this writing the exact hardware
2003 interface is strongly in flux, so no good recommendation can be
2007 bool "kexec file based system call"
2012 depends on CRYPTO_SHA256=y
2014 This is new version of kexec system call. This system call is
2015 file based and takes file descriptors as system call argument
2016 for kernel and initramfs as opposed to list of segments as
2017 accepted by previous system call.
2019 config ARCH_HAS_KEXEC_PURGATORY
2023 bool "Verify kernel signature during kexec_file_load() syscall"
2024 depends on KEXEC_FILE
2027 This option makes the kexec_file_load() syscall check for a valid
2028 signature of the kernel image. The image can still be loaded without
2029 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2030 there's a signature that we can check, then it must be valid.
2032 In addition to this option, you need to enable signature
2033 verification for the corresponding kernel image type being
2034 loaded in order for this to work.
2036 config KEXEC_SIG_FORCE
2037 bool "Require a valid signature in kexec_file_load() syscall"
2038 depends on KEXEC_SIG
2040 This option makes kernel signature verification mandatory for
2041 the kexec_file_load() syscall.
2043 config KEXEC_BZIMAGE_VERIFY_SIG
2044 bool "Enable bzImage signature verification support"
2045 depends on KEXEC_SIG
2046 depends on SIGNED_PE_FILE_VERIFICATION
2047 select SYSTEM_TRUSTED_KEYRING
2049 Enable bzImage signature verification support.
2052 bool "kernel crash dumps"
2053 depends on X86_64 || (X86_32 && HIGHMEM)
2055 Generate crash dump after being started by kexec.
2056 This should be normally only set in special crash dump kernels
2057 which are loaded in the main kernel with kexec-tools into
2058 a specially reserved region and then later executed after
2059 a crash by kdump/kexec. The crash dump kernel must be compiled
2060 to a memory address not used by the main kernel or BIOS using
2061 PHYSICAL_START, or it must be built as a relocatable image
2062 (CONFIG_RELOCATABLE=y).
2063 For more details see Documentation/admin-guide/kdump/kdump.rst
2067 depends on KEXEC && HIBERNATION
2069 Jump between original kernel and kexeced kernel and invoke
2070 code in physical address mode via KEXEC
2072 config PHYSICAL_START
2073 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2076 This gives the physical address where the kernel is loaded.
2078 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2079 bzImage will decompress itself to above physical address and
2080 run from there. Otherwise, bzImage will run from the address where
2081 it has been loaded by the boot loader and will ignore above physical
2084 In normal kdump cases one does not have to set/change this option
2085 as now bzImage can be compiled as a completely relocatable image
2086 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2087 address. This option is mainly useful for the folks who don't want
2088 to use a bzImage for capturing the crash dump and want to use a
2089 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2090 to be specifically compiled to run from a specific memory area
2091 (normally a reserved region) and this option comes handy.
2093 So if you are using bzImage for capturing the crash dump,
2094 leave the value here unchanged to 0x1000000 and set
2095 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2096 for capturing the crash dump change this value to start of
2097 the reserved region. In other words, it can be set based on
2098 the "X" value as specified in the "crashkernel=YM@XM"
2099 command line boot parameter passed to the panic-ed
2100 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2101 for more details about crash dumps.
2103 Usage of bzImage for capturing the crash dump is recommended as
2104 one does not have to build two kernels. Same kernel can be used
2105 as production kernel and capture kernel. Above option should have
2106 gone away after relocatable bzImage support is introduced. But it
2107 is present because there are users out there who continue to use
2108 vmlinux for dump capture. This option should go away down the
2111 Don't change this unless you know what you are doing.
2114 bool "Build a relocatable kernel"
2117 This builds a kernel image that retains relocation information
2118 so it can be loaded someplace besides the default 1MB.
2119 The relocations tend to make the kernel binary about 10% larger,
2120 but are discarded at runtime.
2122 One use is for the kexec on panic case where the recovery kernel
2123 must live at a different physical address than the primary
2126 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2127 it has been loaded at and the compile time physical address
2128 (CONFIG_PHYSICAL_START) is used as the minimum location.
2130 config RANDOMIZE_BASE
2131 bool "Randomize the address of the kernel image (KASLR)"
2132 depends on RELOCATABLE
2135 In support of Kernel Address Space Layout Randomization (KASLR),
2136 this randomizes the physical address at which the kernel image
2137 is decompressed and the virtual address where the kernel
2138 image is mapped, as a security feature that deters exploit
2139 attempts relying on knowledge of the location of kernel
2142 On 64-bit, the kernel physical and virtual addresses are
2143 randomized separately. The physical address will be anywhere
2144 between 16MB and the top of physical memory (up to 64TB). The
2145 virtual address will be randomized from 16MB up to 1GB (9 bits
2146 of entropy). Note that this also reduces the memory space
2147 available to kernel modules from 1.5GB to 1GB.
2149 On 32-bit, the kernel physical and virtual addresses are
2150 randomized together. They will be randomized from 16MB up to
2151 512MB (8 bits of entropy).
2153 Entropy is generated using the RDRAND instruction if it is
2154 supported. If RDTSC is supported, its value is mixed into
2155 the entropy pool as well. If neither RDRAND nor RDTSC are
2156 supported, then entropy is read from the i8254 timer. The
2157 usable entropy is limited by the kernel being built using
2158 2GB addressing, and that PHYSICAL_ALIGN must be at a
2159 minimum of 2MB. As a result, only 10 bits of entropy are
2160 theoretically possible, but the implementations are further
2161 limited due to memory layouts.
2165 # Relocation on x86 needs some additional build support
2166 config X86_NEED_RELOCS
2168 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2170 config PHYSICAL_ALIGN
2171 hex "Alignment value to which kernel should be aligned"
2173 range 0x2000 0x1000000 if X86_32
2174 range 0x200000 0x1000000 if X86_64
2176 This value puts the alignment restrictions on physical address
2177 where kernel is loaded and run from. Kernel is compiled for an
2178 address which meets above alignment restriction.
2180 If bootloader loads the kernel at a non-aligned address and
2181 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2182 address aligned to above value and run from there.
2184 If bootloader loads the kernel at a non-aligned address and
2185 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2186 load address and decompress itself to the address it has been
2187 compiled for and run from there. The address for which kernel is
2188 compiled already meets above alignment restrictions. Hence the
2189 end result is that kernel runs from a physical address meeting
2190 above alignment restrictions.
2192 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2193 this value must be a multiple of 0x200000.
2195 Don't change this unless you know what you are doing.
2197 config DYNAMIC_MEMORY_LAYOUT
2200 This option makes base addresses of vmalloc and vmemmap as well as
2201 __PAGE_OFFSET movable during boot.
2203 config RANDOMIZE_MEMORY
2204 bool "Randomize the kernel memory sections"
2206 depends on RANDOMIZE_BASE
2207 select DYNAMIC_MEMORY_LAYOUT
2208 default RANDOMIZE_BASE
2210 Randomizes the base virtual address of kernel memory sections
2211 (physical memory mapping, vmalloc & vmemmap). This security feature
2212 makes exploits relying on predictable memory locations less reliable.
2214 The order of allocations remains unchanged. Entropy is generated in
2215 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2216 configuration have in average 30,000 different possible virtual
2217 addresses for each memory section.
2221 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2222 hex "Physical memory mapping padding" if EXPERT
2223 depends on RANDOMIZE_MEMORY
2224 default "0xa" if MEMORY_HOTPLUG
2226 range 0x1 0x40 if MEMORY_HOTPLUG
2229 Define the padding in terabytes added to the existing physical
2230 memory size during kernel memory randomization. It is useful
2231 for memory hotplug support but reduces the entropy available for
2232 address randomization.
2234 If unsure, leave at the default value.
2240 config BOOTPARAM_HOTPLUG_CPU0
2241 bool "Set default setting of cpu0_hotpluggable"
2242 depends on HOTPLUG_CPU
2244 Set whether default state of cpu0_hotpluggable is on or off.
2246 Say Y here to enable CPU0 hotplug by default. If this switch
2247 is turned on, there is no need to give cpu0_hotplug kernel
2248 parameter and the CPU0 hotplug feature is enabled by default.
2250 Please note: there are two known CPU0 dependencies if you want
2251 to enable the CPU0 hotplug feature either by this switch or by
2252 cpu0_hotplug kernel parameter.
2254 First, resume from hibernate or suspend always starts from CPU0.
2255 So hibernate and suspend are prevented if CPU0 is offline.
2257 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2258 offline if any interrupt can not migrate out of CPU0. There may
2259 be other CPU0 dependencies.
2261 Please make sure the dependencies are under your control before
2262 you enable this feature.
2264 Say N if you don't want to enable CPU0 hotplug feature by default.
2265 You still can enable the CPU0 hotplug feature at boot by kernel
2266 parameter cpu0_hotplug.
2268 config DEBUG_HOTPLUG_CPU0
2270 prompt "Debug CPU0 hotplug"
2271 depends on HOTPLUG_CPU
2273 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2274 soon as possible and boots up userspace with CPU0 offlined. User
2275 can online CPU0 back after boot time.
2277 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2278 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2279 compilation or giving cpu0_hotplug kernel parameter at boot.
2285 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2286 depends on COMPAT_32
2288 Certain buggy versions of glibc will crash if they are
2289 presented with a 32-bit vDSO that is not mapped at the address
2290 indicated in its segment table.
2292 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2293 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2294 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2295 the only released version with the bug, but OpenSUSE 9
2296 contains a buggy "glibc 2.3.2".
2298 The symptom of the bug is that everything crashes on startup, saying:
2299 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2301 Saying Y here changes the default value of the vdso32 boot
2302 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2303 This works around the glibc bug but hurts performance.
2305 If unsure, say N: if you are compiling your own kernel, you
2306 are unlikely to be using a buggy version of glibc.
2309 prompt "vsyscall table for legacy applications"
2311 default LEGACY_VSYSCALL_XONLY
2313 Legacy user code that does not know how to find the vDSO expects
2314 to be able to issue three syscalls by calling fixed addresses in
2315 kernel space. Since this location is not randomized with ASLR,
2316 it can be used to assist security vulnerability exploitation.
2318 This setting can be changed at boot time via the kernel command
2319 line parameter vsyscall=[emulate|xonly|none].
2321 On a system with recent enough glibc (2.14 or newer) and no
2322 static binaries, you can say None without a performance penalty
2323 to improve security.
2325 If unsure, select "Emulate execution only".
2327 config LEGACY_VSYSCALL_EMULATE
2328 bool "Full emulation"
2330 The kernel traps and emulates calls into the fixed vsyscall
2331 address mapping. This makes the mapping non-executable, but
2332 it still contains readable known contents, which could be
2333 used in certain rare security vulnerability exploits. This
2334 configuration is recommended when using legacy userspace
2335 that still uses vsyscalls along with legacy binary
2336 instrumentation tools that require code to be readable.
2338 An example of this type of legacy userspace is running
2339 Pin on an old binary that still uses vsyscalls.
2341 config LEGACY_VSYSCALL_XONLY
2342 bool "Emulate execution only"
2344 The kernel traps and emulates calls into the fixed vsyscall
2345 address mapping and does not allow reads. This
2346 configuration is recommended when userspace might use the
2347 legacy vsyscall area but support for legacy binary
2348 instrumentation of legacy code is not needed. It mitigates
2349 certain uses of the vsyscall area as an ASLR-bypassing
2352 config LEGACY_VSYSCALL_NONE
2355 There will be no vsyscall mapping at all. This will
2356 eliminate any risk of ASLR bypass due to the vsyscall
2357 fixed address mapping. Attempts to use the vsyscalls
2358 will be reported to dmesg, so that either old or
2359 malicious userspace programs can be identified.
2364 bool "Built-in kernel command line"
2366 Allow for specifying boot arguments to the kernel at
2367 build time. On some systems (e.g. embedded ones), it is
2368 necessary or convenient to provide some or all of the
2369 kernel boot arguments with the kernel itself (that is,
2370 to not rely on the boot loader to provide them.)
2372 To compile command line arguments into the kernel,
2373 set this option to 'Y', then fill in the
2374 boot arguments in CONFIG_CMDLINE.
2376 Systems with fully functional boot loaders (i.e. non-embedded)
2377 should leave this option set to 'N'.
2380 string "Built-in kernel command string"
2381 depends on CMDLINE_BOOL
2384 Enter arguments here that should be compiled into the kernel
2385 image and used at boot time. If the boot loader provides a
2386 command line at boot time, it is appended to this string to
2387 form the full kernel command line, when the system boots.
2389 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2390 change this behavior.
2392 In most cases, the command line (whether built-in or provided
2393 by the boot loader) should specify the device for the root
2396 config CMDLINE_OVERRIDE
2397 bool "Built-in command line overrides boot loader arguments"
2398 depends on CMDLINE_BOOL && CMDLINE != ""
2400 Set this option to 'Y' to have the kernel ignore the boot loader
2401 command line, and use ONLY the built-in command line.
2403 This is used to work around broken boot loaders. This should
2404 be set to 'N' under normal conditions.
2406 config MODIFY_LDT_SYSCALL
2407 bool "Enable the LDT (local descriptor table)" if EXPERT
2410 Linux can allow user programs to install a per-process x86
2411 Local Descriptor Table (LDT) using the modify_ldt(2) system
2412 call. This is required to run 16-bit or segmented code such as
2413 DOSEMU or some Wine programs. It is also used by some very old
2414 threading libraries.
2416 Enabling this feature adds a small amount of overhead to
2417 context switches and increases the low-level kernel attack
2418 surface. Disabling it removes the modify_ldt(2) system call.
2420 Saying 'N' here may make sense for embedded or server kernels.
2422 source "kernel/livepatch/Kconfig"
2426 config ARCH_HAS_ADD_PAGES
2428 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2430 config ARCH_ENABLE_MEMORY_HOTPLUG
2432 depends on X86_64 || (X86_32 && HIGHMEM)
2434 config ARCH_ENABLE_MEMORY_HOTREMOVE
2436 depends on MEMORY_HOTPLUG
2438 config USE_PERCPU_NUMA_NODE_ID
2442 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2444 depends on X86_64 || X86_PAE
2446 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2448 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2450 config ARCH_ENABLE_THP_MIGRATION
2452 depends on X86_64 && TRANSPARENT_HUGEPAGE
2454 menu "Power management and ACPI options"
2456 config ARCH_HIBERNATION_HEADER
2458 depends on HIBERNATION
2460 source "kernel/power/Kconfig"
2462 source "drivers/acpi/Kconfig"
2464 source "drivers/sfi/Kconfig"
2471 tristate "APM (Advanced Power Management) BIOS support"
2472 depends on X86_32 && PM_SLEEP
2474 APM is a BIOS specification for saving power using several different
2475 techniques. This is mostly useful for battery powered laptops with
2476 APM compliant BIOSes. If you say Y here, the system time will be
2477 reset after a RESUME operation, the /proc/apm device will provide
2478 battery status information, and user-space programs will receive
2479 notification of APM "events" (e.g. battery status change).
2481 If you select "Y" here, you can disable actual use of the APM
2482 BIOS by passing the "apm=off" option to the kernel at boot time.
2484 Note that the APM support is almost completely disabled for
2485 machines with more than one CPU.
2487 In order to use APM, you will need supporting software. For location
2488 and more information, read <file:Documentation/power/apm-acpi.rst>
2489 and the Battery Powered Linux mini-HOWTO, available from
2490 <http://www.tldp.org/docs.html#howto>.
2492 This driver does not spin down disk drives (see the hdparm(8)
2493 manpage ("man 8 hdparm") for that), and it doesn't turn off
2494 VESA-compliant "green" monitors.
2496 This driver does not support the TI 4000M TravelMate and the ACER
2497 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2498 desktop machines also don't have compliant BIOSes, and this driver
2499 may cause those machines to panic during the boot phase.
2501 Generally, if you don't have a battery in your machine, there isn't
2502 much point in using this driver and you should say N. If you get
2503 random kernel OOPSes or reboots that don't seem to be related to
2504 anything, try disabling/enabling this option (or disabling/enabling
2507 Some other things you should try when experiencing seemingly random,
2510 1) make sure that you have enough swap space and that it is
2512 2) pass the "no-hlt" option to the kernel
2513 3) switch on floating point emulation in the kernel and pass
2514 the "no387" option to the kernel
2515 4) pass the "floppy=nodma" option to the kernel
2516 5) pass the "mem=4M" option to the kernel (thereby disabling
2517 all but the first 4 MB of RAM)
2518 6) make sure that the CPU is not over clocked.
2519 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2520 8) disable the cache from your BIOS settings
2521 9) install a fan for the video card or exchange video RAM
2522 10) install a better fan for the CPU
2523 11) exchange RAM chips
2524 12) exchange the motherboard.
2526 To compile this driver as a module, choose M here: the
2527 module will be called apm.
2531 config APM_IGNORE_USER_SUSPEND
2532 bool "Ignore USER SUSPEND"
2534 This option will ignore USER SUSPEND requests. On machines with a
2535 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2536 series notebooks, it is necessary to say Y because of a BIOS bug.
2538 config APM_DO_ENABLE
2539 bool "Enable PM at boot time"
2541 Enable APM features at boot time. From page 36 of the APM BIOS
2542 specification: "When disabled, the APM BIOS does not automatically
2543 power manage devices, enter the Standby State, enter the Suspend
2544 State, or take power saving steps in response to CPU Idle calls."
2545 This driver will make CPU Idle calls when Linux is idle (unless this
2546 feature is turned off -- see "Do CPU IDLE calls", below). This
2547 should always save battery power, but more complicated APM features
2548 will be dependent on your BIOS implementation. You may need to turn
2549 this option off if your computer hangs at boot time when using APM
2550 support, or if it beeps continuously instead of suspending. Turn
2551 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2552 T400CDT. This is off by default since most machines do fine without
2557 bool "Make CPU Idle calls when idle"
2559 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2560 On some machines, this can activate improved power savings, such as
2561 a slowed CPU clock rate, when the machine is idle. These idle calls
2562 are made after the idle loop has run for some length of time (e.g.,
2563 333 mS). On some machines, this will cause a hang at boot time or
2564 whenever the CPU becomes idle. (On machines with more than one CPU,
2565 this option does nothing.)
2567 config APM_DISPLAY_BLANK
2568 bool "Enable console blanking using APM"
2570 Enable console blanking using the APM. Some laptops can use this to
2571 turn off the LCD backlight when the screen blanker of the Linux
2572 virtual console blanks the screen. Note that this is only used by
2573 the virtual console screen blanker, and won't turn off the backlight
2574 when using the X Window system. This also doesn't have anything to
2575 do with your VESA-compliant power-saving monitor. Further, this
2576 option doesn't work for all laptops -- it might not turn off your
2577 backlight at all, or it might print a lot of errors to the console,
2578 especially if you are using gpm.
2580 config APM_ALLOW_INTS
2581 bool "Allow interrupts during APM BIOS calls"
2583 Normally we disable external interrupts while we are making calls to
2584 the APM BIOS as a measure to lessen the effects of a badly behaving
2585 BIOS implementation. The BIOS should reenable interrupts if it
2586 needs to. Unfortunately, some BIOSes do not -- especially those in
2587 many of the newer IBM Thinkpads. If you experience hangs when you
2588 suspend, try setting this to Y. Otherwise, say N.
2592 source "drivers/cpufreq/Kconfig"
2594 source "drivers/cpuidle/Kconfig"
2596 source "drivers/idle/Kconfig"
2601 menu "Bus options (PCI etc.)"
2604 prompt "PCI access mode"
2605 depends on X86_32 && PCI
2608 On PCI systems, the BIOS can be used to detect the PCI devices and
2609 determine their configuration. However, some old PCI motherboards
2610 have BIOS bugs and may crash if this is done. Also, some embedded
2611 PCI-based systems don't have any BIOS at all. Linux can also try to
2612 detect the PCI hardware directly without using the BIOS.
2614 With this option, you can specify how Linux should detect the
2615 PCI devices. If you choose "BIOS", the BIOS will be used,
2616 if you choose "Direct", the BIOS won't be used, and if you
2617 choose "MMConfig", then PCI Express MMCONFIG will be used.
2618 If you choose "Any", the kernel will try MMCONFIG, then the
2619 direct access method and falls back to the BIOS if that doesn't
2620 work. If unsure, go with the default, which is "Any".
2625 config PCI_GOMMCONFIG
2642 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2644 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2647 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2650 bool "Support mmconfig PCI config space access" if X86_64
2652 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2653 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2657 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2661 depends on PCI && XEN
2664 config MMCONF_FAM10H
2666 depends on X86_64 && PCI_MMCONFIG && ACPI
2668 config PCI_CNB20LE_QUIRK
2669 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2672 Read the PCI windows out of the CNB20LE host bridge. This allows
2673 PCI hotplug to work on systems with the CNB20LE chipset which do
2676 There's no public spec for this chipset, and this functionality
2677 is known to be incomplete.
2679 You should say N unless you know you need this.
2682 bool "ISA bus support on modern systems" if EXPERT
2684 Expose ISA bus device drivers and options available for selection and
2685 configuration. Enable this option if your target machine has an ISA
2686 bus. ISA is an older system, displaced by PCI and newer bus
2687 architectures -- if your target machine is modern, it probably does
2688 not have an ISA bus.
2692 # x86_64 have no ISA slots, but can have ISA-style DMA.
2694 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2697 Enables ISA-style DMA support for devices requiring such controllers.
2705 Find out whether you have ISA slots on your motherboard. ISA is the
2706 name of a bus system, i.e. the way the CPU talks to the other stuff
2707 inside your box. Other bus systems are PCI, EISA, MicroChannel
2708 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2709 newer boards don't support it. If you have ISA, say Y, otherwise N.
2712 tristate "NatSemi SCx200 support"
2714 This provides basic support for National Semiconductor's
2715 (now AMD's) Geode processors. The driver probes for the
2716 PCI-IDs of several on-chip devices, so its a good dependency
2717 for other scx200_* drivers.
2719 If compiled as a module, the driver is named scx200.
2721 config SCx200HR_TIMER
2722 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2726 This driver provides a clocksource built upon the on-chip
2727 27MHz high-resolution timer. Its also a workaround for
2728 NSC Geode SC-1100's buggy TSC, which loses time when the
2729 processor goes idle (as is done by the scheduler). The
2730 other workaround is idle=poll boot option.
2733 bool "One Laptop Per Child support"
2741 Add support for detecting the unique features of the OLPC
2745 bool "OLPC XO-1 Power Management"
2746 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2748 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2751 bool "OLPC XO-1 Real Time Clock"
2752 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2754 Add support for the XO-1 real time clock, which can be used as a
2755 programmable wakeup source.
2758 bool "OLPC XO-1 SCI extras"
2759 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2763 Add support for SCI-based features of the OLPC XO-1 laptop:
2764 - EC-driven system wakeups
2768 - AC adapter status updates
2769 - Battery status updates
2771 config OLPC_XO15_SCI
2772 bool "OLPC XO-1.5 SCI extras"
2773 depends on OLPC && ACPI
2776 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2777 - EC-driven system wakeups
2778 - AC adapter status updates
2779 - Battery status updates
2782 bool "PCEngines ALIX System Support (LED setup)"
2785 This option enables system support for the PCEngines ALIX.
2786 At present this just sets up LEDs for GPIO control on
2787 ALIX2/3/6 boards. However, other system specific setup should
2790 Note: You must still enable the drivers for GPIO and LED support
2791 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2793 Note: You have to set alix.force=1 for boards with Award BIOS.
2796 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2799 This option enables system support for the Soekris Engineering net5501.
2802 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2806 This option enables system support for the Traverse Technologies GEOS.
2809 bool "Technologic Systems TS-5500 platform support"
2811 select CHECK_SIGNATURE
2815 This option enables system support for the Technologic Systems TS-5500.
2821 depends on CPU_SUP_AMD && PCI
2824 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2826 Firmwares often provide initial graphics framebuffers so the BIOS,
2827 bootloader or kernel can show basic video-output during boot for
2828 user-guidance and debugging. Historically, x86 used the VESA BIOS
2829 Extensions and EFI-framebuffers for this, which are mostly limited
2831 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2832 framebuffers so the new generic system-framebuffer drivers can be
2833 used on x86. If the framebuffer is not compatible with the generic
2834 modes, it is advertised as fallback platform framebuffer so legacy
2835 drivers like efifb, vesafb and uvesafb can pick it up.
2836 If this option is not selected, all system framebuffers are always
2837 marked as fallback platform framebuffers as usual.
2839 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2840 not be able to pick up generic system framebuffers if this option
2841 is selected. You are highly encouraged to enable simplefb as
2842 replacement if you select this option. simplefb can correctly deal
2843 with generic system framebuffers. But you should still keep vesafb
2844 and others enabled as fallback if a system framebuffer is
2845 incompatible with simplefb.
2852 menu "Binary Emulations"
2854 config IA32_EMULATION
2855 bool "IA32 Emulation"
2857 select ARCH_WANT_OLD_COMPAT_IPC
2859 select COMPAT_BINFMT_ELF
2860 select COMPAT_OLD_SIGACTION
2862 Include code to run legacy 32-bit programs under a
2863 64-bit kernel. You should likely turn this on, unless you're
2864 100% sure that you don't have any 32-bit programs left.
2867 tristate "IA32 a.out support"
2868 depends on IA32_EMULATION
2871 Support old a.out binaries in the 32bit emulation.
2874 bool "x32 ABI for 64-bit mode"
2877 Include code to run binaries for the x32 native 32-bit ABI
2878 for 64-bit processors. An x32 process gets access to the
2879 full 64-bit register file and wide data path while leaving
2880 pointers at 32 bits for smaller memory footprint.
2882 You will need a recent binutils (2.22 or later) with
2883 elf32_x86_64 support enabled to compile a kernel with this
2888 depends on IA32_EMULATION || X86_32
2890 select OLD_SIGSUSPEND3
2894 depends on IA32_EMULATION || X86_X32
2897 config COMPAT_FOR_U64_ALIGNMENT
2900 config SYSVIPC_COMPAT
2908 config HAVE_ATOMIC_IOMAP
2912 source "drivers/firmware/Kconfig"
2914 source "arch/x86/kvm/Kconfig"
2916 source "arch/x86/Kconfig.assembler"