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 HAVE_ARCH_KCSAN if X86_64
237 select X86_FEATURE_NAMES if PROC_FS
238 select PROC_PID_ARCH_STATUS if PROC_FS
239 imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
241 config INSTRUCTION_DECODER
243 depends on KPROBES || PERF_EVENTS || UPROBES
247 default "elf32-i386" if X86_32
248 default "elf64-x86-64" if X86_64
250 config LOCKDEP_SUPPORT
253 config STACKTRACE_SUPPORT
259 config ARCH_MMAP_RND_BITS_MIN
263 config ARCH_MMAP_RND_BITS_MAX
267 config ARCH_MMAP_RND_COMPAT_BITS_MIN
270 config ARCH_MMAP_RND_COMPAT_BITS_MAX
276 config GENERIC_ISA_DMA
278 depends on ISA_DMA_API
283 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
285 config GENERIC_BUG_RELATIVE_POINTERS
288 config ARCH_MAY_HAVE_PC_FDC
290 depends on ISA_DMA_API
292 config GENERIC_CALIBRATE_DELAY
295 config ARCH_HAS_CPU_RELAX
298 config ARCH_HAS_CACHE_LINE_SIZE
301 config ARCH_HAS_FILTER_PGPROT
304 config HAVE_SETUP_PER_CPU_AREA
307 config NEED_PER_CPU_EMBED_FIRST_CHUNK
310 config NEED_PER_CPU_PAGE_FIRST_CHUNK
313 config ARCH_HIBERNATION_POSSIBLE
316 config ARCH_SUSPEND_POSSIBLE
319 config ARCH_WANT_GENERAL_HUGETLB
328 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
331 config KASAN_SHADOW_OFFSET
334 default 0xdffffc0000000000
336 config HAVE_INTEL_TXT
338 depends on INTEL_IOMMU && ACPI
342 depends on X86_32 && SMP
346 depends on X86_64 && SMP
348 config X86_32_LAZY_GS
350 depends on X86_32 && !STACKPROTECTOR
352 config ARCH_SUPPORTS_UPROBES
355 config FIX_EARLYCON_MEM
358 config DYNAMIC_PHYSICAL_MASK
361 config PGTABLE_LEVELS
363 default 5 if X86_5LEVEL
368 config CC_HAS_SANE_STACKPROTECTOR
370 default $(success,$(srctree)/scripts/gcc-x86_64-has-stack-protector.sh $(CC)) if 64BIT
371 default $(success,$(srctree)/scripts/gcc-x86_32-has-stack-protector.sh $(CC))
373 We have to make sure stack protector is unconditionally disabled if
374 the compiler produces broken code.
376 menu "Processor type and features"
379 bool "DMA memory allocation support" if EXPERT
382 DMA memory allocation support allows devices with less than 32-bit
383 addressing to allocate within the first 16MB of address space.
384 Disable if no such devices will be used.
389 bool "Symmetric multi-processing support"
391 This enables support for systems with more than one CPU. If you have
392 a system with only one CPU, say N. If you have a system with more
395 If you say N here, the kernel will run on uni- and multiprocessor
396 machines, but will use only one CPU of a multiprocessor machine. If
397 you say Y here, the kernel will run on many, but not all,
398 uniprocessor machines. On a uniprocessor machine, the kernel
399 will run faster if you say N here.
401 Note that if you say Y here and choose architecture "586" or
402 "Pentium" under "Processor family", the kernel will not work on 486
403 architectures. Similarly, multiprocessor kernels for the "PPro"
404 architecture may not work on all Pentium based boards.
406 People using multiprocessor machines who say Y here should also say
407 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
408 Management" code will be disabled if you say Y here.
410 See also <file:Documentation/x86/i386/IO-APIC.rst>,
411 <file:Documentation/admin-guide/lockup-watchdogs.rst> and the SMP-HOWTO available at
412 <http://www.tldp.org/docs.html#howto>.
414 If you don't know what to do here, say N.
416 config X86_FEATURE_NAMES
417 bool "Processor feature human-readable names" if EMBEDDED
420 This option compiles in a table of x86 feature bits and corresponding
421 names. This is required to support /proc/cpuinfo and a few kernel
422 messages. You can disable this to save space, at the expense of
423 making those few kernel messages show numeric feature bits instead.
428 bool "Support x2apic"
429 depends on X86_LOCAL_APIC && X86_64 && (IRQ_REMAP || HYPERVISOR_GUEST)
431 This enables x2apic support on CPUs that have this feature.
433 This allows 32-bit apic IDs (so it can support very large systems),
434 and accesses the local apic via MSRs not via mmio.
436 If you don't know what to do here, say N.
439 bool "Enable MPS table" if ACPI || SFI
441 depends on X86_LOCAL_APIC
443 For old smp systems that do not have proper acpi support. Newer systems
444 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
448 depends on X86_GOLDFISH
451 bool "Avoid speculative indirect branches in kernel"
453 select STACK_VALIDATION if HAVE_STACK_VALIDATION
455 Compile kernel with the retpoline compiler options to guard against
456 kernel-to-user data leaks by avoiding speculative indirect
457 branches. Requires a compiler with -mindirect-branch=thunk-extern
458 support for full protection. The kernel may run slower.
460 config X86_CPU_RESCTRL
461 bool "x86 CPU resource control support"
462 depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
464 select PROC_CPU_RESCTRL if PROC_FS
466 Enable x86 CPU resource control support.
468 Provide support for the allocation and monitoring of system resources
471 Intel calls this Intel Resource Director Technology
472 (Intel(R) RDT). More information about RDT can be found in the
473 Intel x86 Architecture Software Developer Manual.
475 AMD calls this AMD Platform Quality of Service (AMD QoS).
476 More information about AMD QoS can be found in the AMD64 Technology
477 Platform Quality of Service Extensions manual.
483 bool "Support for big SMP systems with more than 8 CPUs"
486 This option is needed for the systems that have more than 8 CPUs.
488 config X86_EXTENDED_PLATFORM
489 bool "Support for extended (non-PC) x86 platforms"
492 If you disable this option then the kernel will only support
493 standard PC platforms. (which covers the vast majority of
496 If you enable this option then you'll be able to select support
497 for the following (non-PC) 32 bit x86 platforms:
498 Goldfish (Android emulator)
501 SGI 320/540 (Visual Workstation)
502 STA2X11-based (e.g. Northville)
503 Moorestown MID devices
505 If you have one of these systems, or if you want to build a
506 generic distribution kernel, say Y here - otherwise say N.
510 config X86_EXTENDED_PLATFORM
511 bool "Support for extended (non-PC) x86 platforms"
514 If you disable this option then the kernel will only support
515 standard PC platforms. (which covers the vast majority of
518 If you enable this option then you'll be able to select support
519 for the following (non-PC) 64 bit x86 platforms:
524 If you have one of these systems, or if you want to build a
525 generic distribution kernel, say Y here - otherwise say N.
527 # This is an alphabetically sorted list of 64 bit extended platforms
528 # Please maintain the alphabetic order if and when there are additions
530 bool "Numascale NumaChip"
532 depends on X86_EXTENDED_PLATFORM
535 depends on X86_X2APIC
536 depends on PCI_MMCONFIG
538 Adds support for Numascale NumaChip large-SMP systems. Needed to
539 enable more than ~168 cores.
540 If you don't have one of these, you should say N here.
544 select HYPERVISOR_GUEST
546 depends on X86_64 && PCI
547 depends on X86_EXTENDED_PLATFORM
550 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
551 supposed to run on these EM64T-based machines. Only choose this option
552 if you have one of these machines.
555 bool "SGI Ultraviolet"
557 depends on X86_EXTENDED_PLATFORM
560 depends on X86_X2APIC
563 This option is needed in order to support SGI Ultraviolet systems.
564 If you don't have one of these, you should say N here.
566 # Following is an alphabetically sorted list of 32 bit extended platforms
567 # Please maintain the alphabetic order if and when there are additions
570 bool "Goldfish (Virtual Platform)"
571 depends on X86_EXTENDED_PLATFORM
573 Enable support for the Goldfish virtual platform used primarily
574 for Android development. Unless you are building for the Android
575 Goldfish emulator say N here.
578 bool "CE4100 TV platform"
580 depends on PCI_GODIRECT
581 depends on X86_IO_APIC
583 depends on X86_EXTENDED_PLATFORM
584 select X86_REBOOTFIXUPS
586 select OF_EARLY_FLATTREE
588 Select for the Intel CE media processor (CE4100) SOC.
589 This option compiles in support for the CE4100 SOC for settop
590 boxes and media devices.
593 bool "Intel MID platform support"
594 depends on X86_EXTENDED_PLATFORM
595 depends on X86_PLATFORM_DEVICES
597 depends on X86_64 || (PCI_GOANY && X86_32)
598 depends on X86_IO_APIC
604 select MFD_INTEL_MSIC
606 Select to build a kernel capable of supporting Intel MID (Mobile
607 Internet Device) platform systems which do not have the PCI legacy
608 interfaces. If you are building for a PC class system say N here.
610 Intel MID platforms are based on an Intel processor and chipset which
611 consume less power than most of the x86 derivatives.
613 config X86_INTEL_QUARK
614 bool "Intel Quark platform support"
616 depends on X86_EXTENDED_PLATFORM
617 depends on X86_PLATFORM_DEVICES
621 depends on X86_IO_APIC
626 Select to include support for Quark X1000 SoC.
627 Say Y here if you have a Quark based system such as the Arduino
628 compatible Intel Galileo.
630 config X86_INTEL_LPSS
631 bool "Intel Low Power Subsystem Support"
632 depends on X86 && ACPI && PCI
637 Select to build support for Intel Low Power Subsystem such as
638 found on Intel Lynxpoint PCH. Selecting this option enables
639 things like clock tree (common clock framework) and pincontrol
640 which are needed by the LPSS peripheral drivers.
642 config X86_AMD_PLATFORM_DEVICE
643 bool "AMD ACPI2Platform devices support"
648 Select to interpret AMD specific ACPI device to platform device
649 such as I2C, UART, GPIO found on AMD Carrizo and later chipsets.
650 I2C and UART depend on COMMON_CLK to set clock. GPIO driver is
651 implemented under PINCTRL subsystem.
654 tristate "Intel SoC IOSF Sideband support for SoC platforms"
657 This option enables sideband register access support for Intel SoC
658 platforms. On these platforms the IOSF sideband is used in lieu of
659 MSR's for some register accesses, mostly but not limited to thermal
660 and power. Drivers may query the availability of this device to
661 determine if they need the sideband in order to work on these
662 platforms. The sideband is available on the following SoC products.
663 This list is not meant to be exclusive.
668 You should say Y if you are running a kernel on one of these SoC's.
670 config IOSF_MBI_DEBUG
671 bool "Enable IOSF sideband access through debugfs"
672 depends on IOSF_MBI && DEBUG_FS
674 Select this option to expose the IOSF sideband access registers (MCR,
675 MDR, MCRX) through debugfs to write and read register information from
676 different units on the SoC. This is most useful for obtaining device
677 state information for debug and analysis. As this is a general access
678 mechanism, users of this option would have specific knowledge of the
679 device they want to access.
681 If you don't require the option or are in doubt, say N.
684 bool "RDC R-321x SoC"
686 depends on X86_EXTENDED_PLATFORM
688 select X86_REBOOTFIXUPS
690 This option is needed for RDC R-321x system-on-chip, also known
692 If you don't have one of these chips, you should say N here.
694 config X86_32_NON_STANDARD
695 bool "Support non-standard 32-bit SMP architectures"
696 depends on X86_32 && SMP
697 depends on X86_EXTENDED_PLATFORM
699 This option compiles in the bigsmp and STA2X11 default
700 subarchitectures. It is intended for a generic binary
701 kernel. If you select them all, kernel will probe it one by
702 one and will fallback to default.
704 # Alphabetically sorted list of Non standard 32 bit platforms
706 config X86_SUPPORTS_MEMORY_FAILURE
708 # MCE code calls memory_failure():
710 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
711 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
712 depends on X86_64 || !SPARSEMEM
713 select ARCH_SUPPORTS_MEMORY_FAILURE
716 bool "STA2X11 Companion Chip Support"
717 depends on X86_32_NON_STANDARD && PCI
722 This adds support for boards based on the STA2X11 IO-Hub,
723 a.k.a. "ConneXt". The chip is used in place of the standard
724 PC chipset, so all "standard" peripherals are missing. If this
725 option is selected the kernel will still be able to boot on
726 standard PC machines.
729 tristate "Eurobraille/Iris poweroff module"
732 The Iris machines from EuroBraille do not have APM or ACPI support
733 to shut themselves down properly. A special I/O sequence is
734 needed to do so, which is what this module does at
737 This is only for Iris machines from EuroBraille.
741 config SCHED_OMIT_FRAME_POINTER
743 prompt "Single-depth WCHAN output"
746 Calculate simpler /proc/<PID>/wchan values. If this option
747 is disabled then wchan values will recurse back to the
748 caller function. This provides more accurate wchan values,
749 at the expense of slightly more scheduling overhead.
751 If in doubt, say "Y".
753 menuconfig HYPERVISOR_GUEST
754 bool "Linux guest support"
756 Say Y here to enable options for running Linux under various hyper-
757 visors. This option enables basic hypervisor detection and platform
760 If you say N, all options in this submenu will be skipped and
761 disabled, and Linux guest support won't be built in.
766 bool "Enable paravirtualization code"
768 This changes the kernel so it can modify itself when it is run
769 under a hypervisor, potentially improving performance significantly
770 over full virtualization. However, when run without a hypervisor
771 the kernel is theoretically slower and slightly larger.
776 config PARAVIRT_DEBUG
777 bool "paravirt-ops debugging"
778 depends on PARAVIRT && DEBUG_KERNEL
780 Enable to debug paravirt_ops internals. Specifically, BUG if
781 a paravirt_op is missing when it is called.
783 config PARAVIRT_SPINLOCKS
784 bool "Paravirtualization layer for spinlocks"
785 depends on PARAVIRT && SMP
787 Paravirtualized spinlocks allow a pvops backend to replace the
788 spinlock implementation with something virtualization-friendly
789 (for example, block the virtual CPU rather than spinning).
791 It has a minimal impact on native kernels and gives a nice performance
792 benefit on paravirtualized KVM / Xen kernels.
794 If you are unsure how to answer this question, answer Y.
796 config X86_HV_CALLBACK_VECTOR
799 source "arch/x86/xen/Kconfig"
802 bool "KVM Guest support (including kvmclock)"
804 select PARAVIRT_CLOCK
805 select ARCH_CPUIDLE_HALTPOLL
808 This option enables various optimizations for running under the KVM
809 hypervisor. It includes a paravirtualized clock, so that instead
810 of relying on a PIT (or probably other) emulation by the
811 underlying device model, the host provides the guest with
812 timing infrastructure such as time of day, and system time
814 config ARCH_CPUIDLE_HALTPOLL
816 prompt "Disable host haltpoll when loading haltpoll driver"
818 If virtualized under KVM, disable host haltpoll.
821 bool "Support for running PVH guests"
823 This option enables the PVH entry point for guest virtual machines
824 as specified in the x86/HVM direct boot ABI.
827 bool "Enable debug information for KVM Guests in debugfs"
828 depends on KVM_GUEST && DEBUG_FS
830 This option enables collection of various statistics for KVM guest.
831 Statistics are displayed in debugfs filesystem. Enabling this option
832 may incur significant overhead.
834 config PARAVIRT_TIME_ACCOUNTING
835 bool "Paravirtual steal time accounting"
838 Select this option to enable fine granularity task steal time
839 accounting. Time spent executing other tasks in parallel with
840 the current vCPU is discounted from the vCPU power. To account for
841 that, there can be a small performance impact.
843 If in doubt, say N here.
845 config PARAVIRT_CLOCK
848 config JAILHOUSE_GUEST
849 bool "Jailhouse non-root cell support"
850 depends on X86_64 && PCI
853 This option allows to run Linux as guest in a Jailhouse non-root
854 cell. You can leave this option disabled if you only want to start
855 Jailhouse and run Linux afterwards in the root cell.
858 bool "ACRN Guest support"
860 select X86_HV_CALLBACK_VECTOR
862 This option allows to run Linux as guest in the ACRN hypervisor. ACRN is
863 a flexible, lightweight reference open-source hypervisor, built with
864 real-time and safety-criticality in mind. It is built for embedded
865 IOT with small footprint and real-time features. More details can be
866 found in https://projectacrn.org/.
868 endif #HYPERVISOR_GUEST
870 source "arch/x86/Kconfig.cpu"
874 prompt "HPET Timer Support" if X86_32
876 Use the IA-PC HPET (High Precision Event Timer) to manage
877 time in preference to the PIT and RTC, if a HPET is
879 HPET is the next generation timer replacing legacy 8254s.
880 The HPET provides a stable time base on SMP
881 systems, unlike the TSC, but it is more expensive to access,
882 as it is off-chip. The interface used is documented
883 in the HPET spec, revision 1.
885 You can safely choose Y here. However, HPET will only be
886 activated if the platform and the BIOS support this feature.
887 Otherwise the 8254 will be used for timing services.
889 Choose N to continue using the legacy 8254 timer.
891 config HPET_EMULATE_RTC
893 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
896 def_bool y if X86_INTEL_MID
897 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
899 depends on X86_INTEL_MID && SFI
901 APB timer is the replacement for 8254, HPET on X86 MID platforms.
902 The APBT provides a stable time base on SMP
903 systems, unlike the TSC, but it is more expensive to access,
904 as it is off-chip. APB timers are always running regardless of CPU
905 C states, they are used as per CPU clockevent device when possible.
907 # Mark as expert because too many people got it wrong.
908 # The code disables itself when not needed.
911 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
912 bool "Enable DMI scanning" if EXPERT
914 Enabled scanning of DMI to identify machine quirks. Say Y
915 here unless you have verified that your setup is not
916 affected by entries in the DMI blacklist. Required by PNP
920 bool "Old AMD GART IOMMU support"
923 depends on X86_64 && PCI && AMD_NB
925 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
926 GART based hardware IOMMUs.
928 The GART supports full DMA access for devices with 32-bit access
929 limitations, on systems with more than 3 GB. This is usually needed
930 for USB, sound, many IDE/SATA chipsets and some other devices.
932 Newer systems typically have a modern AMD IOMMU, supported via
933 the CONFIG_AMD_IOMMU=y config option.
935 In normal configurations this driver is only active when needed:
936 there's more than 3 GB of memory and the system contains a
937 32-bit limited device.
942 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
943 depends on X86_64 && SMP && DEBUG_KERNEL
944 select CPUMASK_OFFSTACK
946 Enable maximum number of CPUS and NUMA Nodes for this architecture.
950 # The maximum number of CPUs supported:
952 # The main config value is NR_CPUS, which defaults to NR_CPUS_DEFAULT,
953 # and which can be configured interactively in the
954 # [NR_CPUS_RANGE_BEGIN ... NR_CPUS_RANGE_END] range.
956 # The ranges are different on 32-bit and 64-bit kernels, depending on
957 # hardware capabilities and scalability features of the kernel.
959 # ( If MAXSMP is enabled we just use the highest possible value and disable
960 # interactive configuration. )
963 config NR_CPUS_RANGE_BEGIN
965 default NR_CPUS_RANGE_END if MAXSMP
969 config NR_CPUS_RANGE_END
972 default 64 if SMP && X86_BIGSMP
973 default 8 if SMP && !X86_BIGSMP
976 config NR_CPUS_RANGE_END
979 default 8192 if SMP && CPUMASK_OFFSTACK
980 default 512 if SMP && !CPUMASK_OFFSTACK
983 config NR_CPUS_DEFAULT
986 default 32 if X86_BIGSMP
990 config NR_CPUS_DEFAULT
993 default 8192 if MAXSMP
998 int "Maximum number of CPUs" if SMP && !MAXSMP
999 range NR_CPUS_RANGE_BEGIN NR_CPUS_RANGE_END
1000 default NR_CPUS_DEFAULT
1002 This allows you to specify the maximum number of CPUs which this
1003 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
1004 supported value is 8192, otherwise the maximum value is 512. The
1005 minimum value which makes sense is 2.
1007 This is purely to save memory: each supported CPU adds about 8KB
1008 to the kernel image.
1015 prompt "Multi-core scheduler support"
1018 Multi-core scheduler support improves the CPU scheduler's decision
1019 making when dealing with multi-core CPU chips at a cost of slightly
1020 increased overhead in some places. If unsure say N here.
1022 config SCHED_MC_PRIO
1023 bool "CPU core priorities scheduler support"
1024 depends on SCHED_MC && CPU_SUP_INTEL
1025 select X86_INTEL_PSTATE
1029 Intel Turbo Boost Max Technology 3.0 enabled CPUs have a
1030 core ordering determined at manufacturing time, which allows
1031 certain cores to reach higher turbo frequencies (when running
1032 single threaded workloads) than others.
1034 Enabling this kernel feature teaches the scheduler about
1035 the TBM3 (aka ITMT) priority order of the CPU cores and adjusts the
1036 scheduler's CPU selection logic accordingly, so that higher
1037 overall system performance can be achieved.
1039 This feature will have no effect on CPUs without this feature.
1041 If unsure say Y here.
1045 depends on !SMP && X86_LOCAL_APIC
1048 bool "Local APIC support on uniprocessors" if !PCI_MSI
1050 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
1052 A local APIC (Advanced Programmable Interrupt Controller) is an
1053 integrated interrupt controller in the CPU. If you have a single-CPU
1054 system which has a processor with a local APIC, you can say Y here to
1055 enable and use it. If you say Y here even though your machine doesn't
1056 have a local APIC, then the kernel will still run with no slowdown at
1057 all. The local APIC supports CPU-generated self-interrupts (timer,
1058 performance counters), and the NMI watchdog which detects hard
1061 config X86_UP_IOAPIC
1062 bool "IO-APIC support on uniprocessors"
1063 depends on X86_UP_APIC
1065 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
1066 SMP-capable replacement for PC-style interrupt controllers. Most
1067 SMP systems and many recent uniprocessor systems have one.
1069 If you have a single-CPU system with an IO-APIC, you can say Y here
1070 to use it. If you say Y here even though your machine doesn't have
1071 an IO-APIC, then the kernel will still run with no slowdown at all.
1073 config X86_LOCAL_APIC
1075 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
1076 select IRQ_DOMAIN_HIERARCHY
1077 select PCI_MSI_IRQ_DOMAIN if PCI_MSI
1081 depends on X86_LOCAL_APIC || X86_UP_IOAPIC
1083 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
1084 bool "Reroute for broken boot IRQs"
1085 depends on X86_IO_APIC
1087 This option enables a workaround that fixes a source of
1088 spurious interrupts. This is recommended when threaded
1089 interrupt handling is used on systems where the generation of
1090 superfluous "boot interrupts" cannot be disabled.
1092 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
1093 entry in the chipset's IO-APIC is masked (as, e.g. the RT
1094 kernel does during interrupt handling). On chipsets where this
1095 boot IRQ generation cannot be disabled, this workaround keeps
1096 the original IRQ line masked so that only the equivalent "boot
1097 IRQ" is delivered to the CPUs. The workaround also tells the
1098 kernel to set up the IRQ handler on the boot IRQ line. In this
1099 way only one interrupt is delivered to the kernel. Otherwise
1100 the spurious second interrupt may cause the kernel to bring
1101 down (vital) interrupt lines.
1103 Only affects "broken" chipsets. Interrupt sharing may be
1104 increased on these systems.
1107 bool "Machine Check / overheating reporting"
1108 select GENERIC_ALLOCATOR
1111 Machine Check support allows the processor to notify the
1112 kernel if it detects a problem (e.g. overheating, data corruption).
1113 The action the kernel takes depends on the severity of the problem,
1114 ranging from warning messages to halting the machine.
1116 config X86_MCELOG_LEGACY
1117 bool "Support for deprecated /dev/mcelog character device"
1120 Enable support for /dev/mcelog which is needed by the old mcelog
1121 userspace logging daemon. Consider switching to the new generation
1124 config X86_MCE_INTEL
1126 prompt "Intel MCE features"
1127 depends on X86_MCE && X86_LOCAL_APIC
1129 Additional support for intel specific MCE features such as
1130 the thermal monitor.
1134 prompt "AMD MCE features"
1135 depends on X86_MCE && X86_LOCAL_APIC && AMD_NB
1137 Additional support for AMD specific MCE features such as
1138 the DRAM Error Threshold.
1140 config X86_ANCIENT_MCE
1141 bool "Support for old Pentium 5 / WinChip machine checks"
1142 depends on X86_32 && X86_MCE
1144 Include support for machine check handling on old Pentium 5 or WinChip
1145 systems. These typically need to be enabled explicitly on the command
1148 config X86_MCE_THRESHOLD
1149 depends on X86_MCE_AMD || X86_MCE_INTEL
1152 config X86_MCE_INJECT
1153 depends on X86_MCE && X86_LOCAL_APIC && DEBUG_FS
1154 tristate "Machine check injector support"
1156 Provide support for injecting machine checks for testing purposes.
1157 If you don't know what a machine check is and you don't do kernel
1158 QA it is safe to say n.
1160 config X86_THERMAL_VECTOR
1162 depends on X86_MCE_INTEL
1164 source "arch/x86/events/Kconfig"
1166 config X86_LEGACY_VM86
1167 bool "Legacy VM86 support"
1170 This option allows user programs to put the CPU into V8086
1171 mode, which is an 80286-era approximation of 16-bit real mode.
1173 Some very old versions of X and/or vbetool require this option
1174 for user mode setting. Similarly, DOSEMU will use it if
1175 available to accelerate real mode DOS programs. However, any
1176 recent version of DOSEMU, X, or vbetool should be fully
1177 functional even without kernel VM86 support, as they will all
1178 fall back to software emulation. Nevertheless, if you are using
1179 a 16-bit DOS program where 16-bit performance matters, vm86
1180 mode might be faster than emulation and you might want to
1183 Note that any app that works on a 64-bit kernel is unlikely to
1184 need this option, as 64-bit kernels don't, and can't, support
1185 V8086 mode. This option is also unrelated to 16-bit protected
1186 mode and is not needed to run most 16-bit programs under Wine.
1188 Enabling this option increases the complexity of the kernel
1189 and slows down exception handling a tiny bit.
1191 If unsure, say N here.
1195 default X86_LEGACY_VM86
1198 bool "Enable support for 16-bit segments" if EXPERT
1200 depends on MODIFY_LDT_SYSCALL
1202 This option is required by programs like Wine to run 16-bit
1203 protected mode legacy code on x86 processors. Disabling
1204 this option saves about 300 bytes on i386, or around 6K text
1205 plus 16K runtime memory on x86-64,
1209 depends on X86_16BIT && X86_32
1213 depends on X86_16BIT && X86_64
1215 config X86_VSYSCALL_EMULATION
1216 bool "Enable vsyscall emulation" if EXPERT
1220 This enables emulation of the legacy vsyscall page. Disabling
1221 it is roughly equivalent to booting with vsyscall=none, except
1222 that it will also disable the helpful warning if a program
1223 tries to use a vsyscall. With this option set to N, offending
1224 programs will just segfault, citing addresses of the form
1227 This option is required by many programs built before 2013, and
1228 care should be used even with newer programs if set to N.
1230 Disabling this option saves about 7K of kernel size and
1231 possibly 4K of additional runtime pagetable memory.
1233 config X86_IOPL_IOPERM
1234 bool "IOPERM and IOPL Emulation"
1237 This enables the ioperm() and iopl() syscalls which are necessary
1238 for legacy applications.
1240 Legacy IOPL support is an overbroad mechanism which allows user
1241 space aside of accessing all 65536 I/O ports also to disable
1242 interrupts. To gain this access the caller needs CAP_SYS_RAWIO
1243 capabilities and permission from potentially active security
1246 The emulation restricts the functionality of the syscall to
1247 only allowing the full range I/O port access, but prevents the
1248 ability to disable interrupts from user space which would be
1249 granted if the hardware IOPL mechanism would be used.
1252 tristate "Toshiba Laptop support"
1255 This adds a driver to safely access the System Management Mode of
1256 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
1257 not work on models with a Phoenix BIOS. The System Management Mode
1258 is used to set the BIOS and power saving options on Toshiba portables.
1260 For information on utilities to make use of this driver see the
1261 Toshiba Linux utilities web site at:
1262 <http://www.buzzard.org.uk/toshiba/>.
1264 Say Y if you intend to run this kernel on a Toshiba portable.
1268 tristate "Dell i8k legacy laptop support"
1270 select SENSORS_DELL_SMM
1272 This option enables legacy /proc/i8k userspace interface in hwmon
1273 dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
1274 temperature and allows controlling fan speeds of Dell laptops via
1275 System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
1276 it reports also power and hotkey status. For fan speed control is
1277 needed userspace package i8kutils.
1279 Say Y if you intend to run this kernel on old Dell laptops or want to
1280 use userspace package i8kutils.
1283 config X86_REBOOTFIXUPS
1284 bool "Enable X86 board specific fixups for reboot"
1287 This enables chipset and/or board specific fixups to be done
1288 in order to get reboot to work correctly. This is only needed on
1289 some combinations of hardware and BIOS. The symptom, for which
1290 this config is intended, is when reboot ends with a stalled/hung
1293 Currently, the only fixup is for the Geode machines using
1294 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1296 Say Y if you want to enable the fixup. Currently, it's safe to
1297 enable this option even if you don't need it.
1301 bool "CPU microcode loading support"
1303 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1306 If you say Y here, you will be able to update the microcode on
1307 Intel and AMD processors. The Intel support is for the IA32 family,
1308 e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. The
1309 AMD support is for families 0x10 and later. You will obviously need
1310 the actual microcode binary data itself which is not shipped with
1313 The preferred method to load microcode from a detached initrd is described
1314 in Documentation/x86/microcode.rst. For that you need to enable
1315 CONFIG_BLK_DEV_INITRD in order for the loader to be able to scan the
1316 initrd for microcode blobs.
1318 In addition, you can build the microcode into the kernel. For that you
1319 need to add the vendor-supplied microcode to the CONFIG_EXTRA_FIRMWARE
1322 config MICROCODE_INTEL
1323 bool "Intel microcode loading support"
1324 depends on MICROCODE
1328 This options enables microcode patch loading support for Intel
1331 For the current Intel microcode data package go to
1332 <https://downloadcenter.intel.com> and search for
1333 'Linux Processor Microcode Data File'.
1335 config MICROCODE_AMD
1336 bool "AMD microcode loading support"
1337 depends on MICROCODE
1340 If you select this option, microcode patch loading support for AMD
1341 processors will be enabled.
1343 config MICROCODE_OLD_INTERFACE
1344 bool "Ancient loading interface (DEPRECATED)"
1346 depends on MICROCODE
1348 DO NOT USE THIS! This is the ancient /dev/cpu/microcode interface
1349 which was used by userspace tools like iucode_tool and microcode.ctl.
1350 It is inadequate because it runs too late to be able to properly
1351 load microcode on a machine and it needs special tools. Instead, you
1352 should've switched to the early loading method with the initrd or
1353 builtin microcode by now: Documentation/x86/microcode.rst
1356 tristate "/dev/cpu/*/msr - Model-specific register support"
1358 This device gives privileged processes access to the x86
1359 Model-Specific Registers (MSRs). It is a character device with
1360 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1361 MSR accesses are directed to a specific CPU on multi-processor
1365 tristate "/dev/cpu/*/cpuid - CPU information support"
1367 This device gives processes access to the x86 CPUID instruction to
1368 be executed on a specific processor. It is a character device
1369 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1373 prompt "High Memory Support"
1380 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1381 However, the address space of 32-bit x86 processors is only 4
1382 Gigabytes large. That means that, if you have a large amount of
1383 physical memory, not all of it can be "permanently mapped" by the
1384 kernel. The physical memory that's not permanently mapped is called
1387 If you are compiling a kernel which will never run on a machine with
1388 more than 1 Gigabyte total physical RAM, answer "off" here (default
1389 choice and suitable for most users). This will result in a "3GB/1GB"
1390 split: 3GB are mapped so that each process sees a 3GB virtual memory
1391 space and the remaining part of the 4GB virtual memory space is used
1392 by the kernel to permanently map as much physical memory as
1395 If the machine has between 1 and 4 Gigabytes physical RAM, then
1398 If more than 4 Gigabytes is used then answer "64GB" here. This
1399 selection turns Intel PAE (Physical Address Extension) mode on.
1400 PAE implements 3-level paging on IA32 processors. PAE is fully
1401 supported by Linux, PAE mode is implemented on all recent Intel
1402 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1403 then the kernel will not boot on CPUs that don't support PAE!
1405 The actual amount of total physical memory will either be
1406 auto detected or can be forced by using a kernel command line option
1407 such as "mem=256M". (Try "man bootparam" or see the documentation of
1408 your boot loader (lilo or loadlin) about how to pass options to the
1409 kernel at boot time.)
1411 If unsure, say "off".
1416 Select this if you have a 32-bit processor and between 1 and 4
1417 gigabytes of physical RAM.
1421 depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
1424 Select this if you have a 32-bit processor and more than 4
1425 gigabytes of physical RAM.
1430 prompt "Memory split" if EXPERT
1434 Select the desired split between kernel and user memory.
1436 If the address range available to the kernel is less than the
1437 physical memory installed, the remaining memory will be available
1438 as "high memory". Accessing high memory is a little more costly
1439 than low memory, as it needs to be mapped into the kernel first.
1440 Note that increasing the kernel address space limits the range
1441 available to user programs, making the address space there
1442 tighter. Selecting anything other than the default 3G/1G split
1443 will also likely make your kernel incompatible with binary-only
1446 If you are not absolutely sure what you are doing, leave this
1450 bool "3G/1G user/kernel split"
1451 config VMSPLIT_3G_OPT
1453 bool "3G/1G user/kernel split (for full 1G low memory)"
1455 bool "2G/2G user/kernel split"
1456 config VMSPLIT_2G_OPT
1458 bool "2G/2G user/kernel split (for full 2G low memory)"
1460 bool "1G/3G user/kernel split"
1465 default 0xB0000000 if VMSPLIT_3G_OPT
1466 default 0x80000000 if VMSPLIT_2G
1467 default 0x78000000 if VMSPLIT_2G_OPT
1468 default 0x40000000 if VMSPLIT_1G
1474 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1477 bool "PAE (Physical Address Extension) Support"
1478 depends on X86_32 && !HIGHMEM4G
1479 select PHYS_ADDR_T_64BIT
1482 PAE is required for NX support, and furthermore enables
1483 larger swapspace support for non-overcommit purposes. It
1484 has the cost of more pagetable lookup overhead, and also
1485 consumes more pagetable space per process.
1488 bool "Enable 5-level page tables support"
1490 select DYNAMIC_MEMORY_LAYOUT
1491 select SPARSEMEM_VMEMMAP
1494 5-level paging enables access to larger address space:
1495 upto 128 PiB of virtual address space and 4 PiB of
1496 physical address space.
1498 It will be supported by future Intel CPUs.
1500 A kernel with the option enabled can be booted on machines that
1501 support 4- or 5-level paging.
1503 See Documentation/x86/x86_64/5level-paging.rst for more
1508 config X86_DIRECT_GBPAGES
1512 Certain kernel features effectively disable kernel
1513 linear 1 GB mappings (even if the CPU otherwise
1514 supports them), so don't confuse the user by printing
1515 that we have them enabled.
1517 config X86_CPA_STATISTICS
1518 bool "Enable statistic for Change Page Attribute"
1521 Expose statistics about the Change Page Attribute mechanism, which
1522 helps to determine the effectiveness of preserving large and huge
1523 page mappings when mapping protections are changed.
1525 config AMD_MEM_ENCRYPT
1526 bool "AMD Secure Memory Encryption (SME) support"
1527 depends on X86_64 && CPU_SUP_AMD
1528 select DMA_COHERENT_POOL
1529 select DYNAMIC_PHYSICAL_MASK
1530 select ARCH_USE_MEMREMAP_PROT
1531 select ARCH_HAS_FORCE_DMA_UNENCRYPTED
1533 Say yes to enable support for the encryption of system memory.
1534 This requires an AMD processor that supports Secure Memory
1537 config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
1538 bool "Activate AMD Secure Memory Encryption (SME) by default"
1540 depends on AMD_MEM_ENCRYPT
1542 Say yes to have system memory encrypted by default if running on
1543 an AMD processor that supports Secure Memory Encryption (SME).
1545 If set to Y, then the encryption of system memory can be
1546 deactivated with the mem_encrypt=off command line option.
1548 If set to N, then the encryption of system memory can be
1549 activated with the mem_encrypt=on command line option.
1551 # Common NUMA Features
1553 bool "NUMA Memory Allocation and Scheduler Support"
1555 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1556 default y if X86_BIGSMP
1558 Enable NUMA (Non-Uniform Memory Access) support.
1560 The kernel will try to allocate memory used by a CPU on the
1561 local memory controller of the CPU and add some more
1562 NUMA awareness to the kernel.
1564 For 64-bit this is recommended if the system is Intel Core i7
1565 (or later), AMD Opteron, or EM64T NUMA.
1567 For 32-bit this is only needed if you boot a 32-bit
1568 kernel on a 64-bit NUMA platform.
1570 Otherwise, you should say N.
1574 prompt "Old style AMD Opteron NUMA detection"
1575 depends on X86_64 && NUMA && PCI
1577 Enable AMD NUMA node topology detection. You should say Y here if
1578 you have a multi processor AMD system. This uses an old method to
1579 read the NUMA configuration directly from the builtin Northbridge
1580 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1581 which also takes priority if both are compiled in.
1583 config X86_64_ACPI_NUMA
1585 prompt "ACPI NUMA detection"
1586 depends on X86_64 && NUMA && ACPI && PCI
1589 Enable ACPI SRAT based node topology detection.
1592 bool "NUMA emulation"
1595 Enable NUMA emulation. A flat machine will be split
1596 into virtual nodes when booted with "numa=fake=N", where N is the
1597 number of nodes. This is only useful for debugging.
1600 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1602 default "10" if MAXSMP
1603 default "6" if X86_64
1605 depends on NEED_MULTIPLE_NODES
1607 Specify the maximum number of NUMA Nodes available on the target
1608 system. Increases memory reserved to accommodate various tables.
1610 config ARCH_FLATMEM_ENABLE
1612 depends on X86_32 && !NUMA
1614 config ARCH_SPARSEMEM_ENABLE
1616 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1617 select SPARSEMEM_STATIC if X86_32
1618 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1620 config ARCH_SPARSEMEM_DEFAULT
1621 def_bool X86_64 || (NUMA && X86_32)
1623 config ARCH_SELECT_MEMORY_MODEL
1625 depends on ARCH_SPARSEMEM_ENABLE
1627 config ARCH_MEMORY_PROBE
1628 bool "Enable sysfs memory/probe interface"
1629 depends on X86_64 && MEMORY_HOTPLUG
1631 This option enables a sysfs memory/probe interface for testing.
1632 See Documentation/admin-guide/mm/memory-hotplug.rst for more information.
1633 If you are unsure how to answer this question, answer N.
1635 config ARCH_PROC_KCORE_TEXT
1637 depends on X86_64 && PROC_KCORE
1639 config ILLEGAL_POINTER_VALUE
1642 default 0xdead000000000000 if X86_64
1644 config X86_PMEM_LEGACY_DEVICE
1647 config X86_PMEM_LEGACY
1648 tristate "Support non-standard NVDIMMs and ADR protected memory"
1649 depends on PHYS_ADDR_T_64BIT
1651 select X86_PMEM_LEGACY_DEVICE
1652 select NUMA_KEEP_MEMINFO if NUMA
1655 Treat memory marked using the non-standard e820 type of 12 as used
1656 by the Intel Sandy Bridge-EP reference BIOS as protected memory.
1657 The kernel will offer these regions to the 'pmem' driver so
1658 they can be used for persistent storage.
1663 bool "Allocate 3rd-level pagetables from highmem"
1666 The VM uses one page table entry for each page of physical memory.
1667 For systems with a lot of RAM, this can be wasteful of precious
1668 low memory. Setting this option will put user-space page table
1669 entries in high memory.
1671 config X86_CHECK_BIOS_CORRUPTION
1672 bool "Check for low memory corruption"
1674 Periodically check for memory corruption in low memory, which
1675 is suspected to be caused by BIOS. Even when enabled in the
1676 configuration, it is disabled at runtime. Enable it by
1677 setting "memory_corruption_check=1" on the kernel command
1678 line. By default it scans the low 64k of memory every 60
1679 seconds; see the memory_corruption_check_size and
1680 memory_corruption_check_period parameters in
1681 Documentation/admin-guide/kernel-parameters.rst to adjust this.
1683 When enabled with the default parameters, this option has
1684 almost no overhead, as it reserves a relatively small amount
1685 of memory and scans it infrequently. It both detects corruption
1686 and prevents it from affecting the running system.
1688 It is, however, intended as a diagnostic tool; if repeatable
1689 BIOS-originated corruption always affects the same memory,
1690 you can use memmap= to prevent the kernel from using that
1693 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1694 bool "Set the default setting of memory_corruption_check"
1695 depends on X86_CHECK_BIOS_CORRUPTION
1698 Set whether the default state of memory_corruption_check is
1701 config X86_RESERVE_LOW
1702 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1706 Specify the amount of low memory to reserve for the BIOS.
1708 The first page contains BIOS data structures that the kernel
1709 must not use, so that page must always be reserved.
1711 By default we reserve the first 64K of physical RAM, as a
1712 number of BIOSes are known to corrupt that memory range
1713 during events such as suspend/resume or monitor cable
1714 insertion, so it must not be used by the kernel.
1716 You can set this to 4 if you are absolutely sure that you
1717 trust the BIOS to get all its memory reservations and usages
1718 right. If you know your BIOS have problems beyond the
1719 default 64K area, you can set this to 640 to avoid using the
1720 entire low memory range.
1722 If you have doubts about the BIOS (e.g. suspend/resume does
1723 not work or there's kernel crashes after certain hardware
1724 hotplug events) then you might want to enable
1725 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1726 typical corruption patterns.
1728 Leave this to the default value of 64 if you are unsure.
1730 config MATH_EMULATION
1732 depends on MODIFY_LDT_SYSCALL
1733 prompt "Math emulation" if X86_32 && (M486SX || MELAN)
1735 Linux can emulate a math coprocessor (used for floating point
1736 operations) if you don't have one. 486DX and Pentium processors have
1737 a math coprocessor built in, 486SX and 386 do not, unless you added
1738 a 487DX or 387, respectively. (The messages during boot time can
1739 give you some hints here ["man dmesg"].) Everyone needs either a
1740 coprocessor or this emulation.
1742 If you don't have a math coprocessor, you need to say Y here; if you
1743 say Y here even though you have a coprocessor, the coprocessor will
1744 be used nevertheless. (This behavior can be changed with the kernel
1745 command line option "no387", which comes handy if your coprocessor
1746 is broken. Try "man bootparam" or see the documentation of your boot
1747 loader (lilo or loadlin) about how to pass options to the kernel at
1748 boot time.) This means that it is a good idea to say Y here if you
1749 intend to use this kernel on different machines.
1751 More information about the internals of the Linux math coprocessor
1752 emulation can be found in <file:arch/x86/math-emu/README>.
1754 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1755 kernel, it won't hurt.
1759 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1761 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1762 the Memory Type Range Registers (MTRRs) may be used to control
1763 processor access to memory ranges. This is most useful if you have
1764 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1765 allows bus write transfers to be combined into a larger transfer
1766 before bursting over the PCI/AGP bus. This can increase performance
1767 of image write operations 2.5 times or more. Saying Y here creates a
1768 /proc/mtrr file which may be used to manipulate your processor's
1769 MTRRs. Typically the X server should use this.
1771 This code has a reasonably generic interface so that similar
1772 control registers on other processors can be easily supported
1775 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1776 Registers (ARRs) which provide a similar functionality to MTRRs. For
1777 these, the ARRs are used to emulate the MTRRs.
1778 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1779 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1780 write-combining. All of these processors are supported by this code
1781 and it makes sense to say Y here if you have one of them.
1783 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1784 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1785 can lead to all sorts of problems, so it's good to say Y here.
1787 You can safely say Y even if your machine doesn't have MTRRs, you'll
1788 just add about 9 KB to your kernel.
1790 See <file:Documentation/x86/mtrr.rst> for more information.
1792 config MTRR_SANITIZER
1794 prompt "MTRR cleanup support"
1797 Convert MTRR layout from continuous to discrete, so X drivers can
1798 add writeback entries.
1800 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1801 The largest mtrr entry size for a continuous block can be set with
1806 config MTRR_SANITIZER_ENABLE_DEFAULT
1807 int "MTRR cleanup enable value (0-1)"
1810 depends on MTRR_SANITIZER
1812 Enable mtrr cleanup default value
1814 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1815 int "MTRR cleanup spare reg num (0-7)"
1818 depends on MTRR_SANITIZER
1820 mtrr cleanup spare entries default, it can be changed via
1821 mtrr_spare_reg_nr=N on the kernel command line.
1825 prompt "x86 PAT support" if EXPERT
1828 Use PAT attributes to setup page level cache control.
1830 PATs are the modern equivalents of MTRRs and are much more
1831 flexible than MTRRs.
1833 Say N here if you see bootup problems (boot crash, boot hang,
1834 spontaneous reboots) or a non-working video driver.
1838 config ARCH_USES_PG_UNCACHED
1844 prompt "x86 architectural random number generator" if EXPERT
1846 Enable the x86 architectural RDRAND instruction
1847 (Intel Bull Mountain technology) to generate random numbers.
1848 If supported, this is a high bandwidth, cryptographically
1849 secure hardware random number generator.
1853 prompt "Supervisor Mode Access Prevention" if EXPERT
1855 Supervisor Mode Access Prevention (SMAP) is a security
1856 feature in newer Intel processors. There is a small
1857 performance cost if this enabled and turned on; there is
1858 also a small increase in the kernel size if this is enabled.
1864 prompt "User Mode Instruction Prevention" if EXPERT
1866 User Mode Instruction Prevention (UMIP) is a security feature in
1867 some x86 processors. If enabled, a general protection fault is
1868 issued if the SGDT, SLDT, SIDT, SMSW or STR instructions are
1869 executed in user mode. These instructions unnecessarily expose
1870 information about the hardware state.
1872 The vast majority of applications do not use these instructions.
1873 For the very few that do, software emulation is provided in
1874 specific cases in protected and virtual-8086 modes. Emulated
1877 config X86_INTEL_MEMORY_PROTECTION_KEYS
1878 prompt "Memory Protection Keys"
1880 # Note: only available in 64-bit mode
1881 depends on X86_64 && (CPU_SUP_INTEL || CPU_SUP_AMD)
1882 select ARCH_USES_HIGH_VMA_FLAGS
1883 select ARCH_HAS_PKEYS
1885 Memory Protection Keys provides a mechanism for enforcing
1886 page-based protections, but without requiring modification of the
1887 page tables when an application changes protection domains.
1889 For details, see Documentation/core-api/protection-keys.rst
1894 prompt "TSX enable mode"
1895 depends on CPU_SUP_INTEL
1896 default X86_INTEL_TSX_MODE_OFF
1898 Intel's TSX (Transactional Synchronization Extensions) feature
1899 allows to optimize locking protocols through lock elision which
1900 can lead to a noticeable performance boost.
1902 On the other hand it has been shown that TSX can be exploited
1903 to form side channel attacks (e.g. TAA) and chances are there
1904 will be more of those attacks discovered in the future.
1906 Therefore TSX is not enabled by default (aka tsx=off). An admin
1907 might override this decision by tsx=on the command line parameter.
1908 Even with TSX enabled, the kernel will attempt to enable the best
1909 possible TAA mitigation setting depending on the microcode available
1910 for the particular machine.
1912 This option allows to set the default tsx mode between tsx=on, =off
1913 and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
1916 Say off if not sure, auto if TSX is in use but it should be used on safe
1917 platforms or on if TSX is in use and the security aspect of tsx is not
1920 config X86_INTEL_TSX_MODE_OFF
1923 TSX is disabled if possible - equals to tsx=off command line parameter.
1925 config X86_INTEL_TSX_MODE_ON
1928 TSX is always enabled on TSX capable HW - equals the tsx=on command
1931 config X86_INTEL_TSX_MODE_AUTO
1934 TSX is enabled on TSX capable HW that is believed to be safe against
1935 side channel attacks- equals the tsx=auto command line parameter.
1939 bool "EFI runtime service support"
1942 select EFI_RUNTIME_WRAPPERS
1944 This enables the kernel to use EFI runtime services that are
1945 available (such as the EFI variable services).
1947 This option is only useful on systems that have EFI firmware.
1948 In addition, you should use the latest ELILO loader available
1949 at <http://elilo.sourceforge.net> in order to take advantage
1950 of EFI runtime services. However, even with this option, the
1951 resultant kernel should continue to boot on existing non-EFI
1955 bool "EFI stub support"
1956 depends on EFI && !X86_USE_3DNOW
1957 depends on $(cc-option,-mabi=ms) || X86_32
1960 This kernel feature allows a bzImage to be loaded directly
1961 by EFI firmware without the use of a bootloader.
1963 See Documentation/admin-guide/efi-stub.rst for more information.
1966 bool "EFI mixed-mode support"
1967 depends on EFI_STUB && X86_64
1969 Enabling this feature allows a 64-bit kernel to be booted
1970 on a 32-bit firmware, provided that your CPU supports 64-bit
1973 Note that it is not possible to boot a mixed-mode enabled
1974 kernel via the EFI boot stub - a bootloader that supports
1975 the EFI handover protocol must be used.
1981 prompt "Enable seccomp to safely compute untrusted bytecode"
1983 This kernel feature is useful for number crunching applications
1984 that may need to compute untrusted bytecode during their
1985 execution. By using pipes or other transports made available to
1986 the process as file descriptors supporting the read/write
1987 syscalls, it's possible to isolate those applications in
1988 their own address space using seccomp. Once seccomp is
1989 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1990 and the task is only allowed to execute a few safe syscalls
1991 defined by each seccomp mode.
1993 If unsure, say Y. Only embedded should say N here.
1995 source "kernel/Kconfig.hz"
1998 bool "kexec system call"
2001 kexec is a system call that implements the ability to shutdown your
2002 current kernel, and to start another kernel. It is like a reboot
2003 but it is independent of the system firmware. And like a reboot
2004 you can start any kernel with it, not just Linux.
2006 The name comes from the similarity to the exec system call.
2008 It is an ongoing process to be certain the hardware in a machine
2009 is properly shutdown, so do not be surprised if this code does not
2010 initially work for you. As of this writing the exact hardware
2011 interface is strongly in flux, so no good recommendation can be
2015 bool "kexec file based system call"
2020 depends on CRYPTO_SHA256=y
2022 This is new version of kexec system call. This system call is
2023 file based and takes file descriptors as system call argument
2024 for kernel and initramfs as opposed to list of segments as
2025 accepted by previous system call.
2027 config ARCH_HAS_KEXEC_PURGATORY
2031 bool "Verify kernel signature during kexec_file_load() syscall"
2032 depends on KEXEC_FILE
2035 This option makes the kexec_file_load() syscall check for a valid
2036 signature of the kernel image. The image can still be loaded without
2037 a valid signature unless you also enable KEXEC_SIG_FORCE, though if
2038 there's a signature that we can check, then it must be valid.
2040 In addition to this option, you need to enable signature
2041 verification for the corresponding kernel image type being
2042 loaded in order for this to work.
2044 config KEXEC_SIG_FORCE
2045 bool "Require a valid signature in kexec_file_load() syscall"
2046 depends on KEXEC_SIG
2048 This option makes kernel signature verification mandatory for
2049 the kexec_file_load() syscall.
2051 config KEXEC_BZIMAGE_VERIFY_SIG
2052 bool "Enable bzImage signature verification support"
2053 depends on KEXEC_SIG
2054 depends on SIGNED_PE_FILE_VERIFICATION
2055 select SYSTEM_TRUSTED_KEYRING
2057 Enable bzImage signature verification support.
2060 bool "kernel crash dumps"
2061 depends on X86_64 || (X86_32 && HIGHMEM)
2063 Generate crash dump after being started by kexec.
2064 This should be normally only set in special crash dump kernels
2065 which are loaded in the main kernel with kexec-tools into
2066 a specially reserved region and then later executed after
2067 a crash by kdump/kexec. The crash dump kernel must be compiled
2068 to a memory address not used by the main kernel or BIOS using
2069 PHYSICAL_START, or it must be built as a relocatable image
2070 (CONFIG_RELOCATABLE=y).
2071 For more details see Documentation/admin-guide/kdump/kdump.rst
2075 depends on KEXEC && HIBERNATION
2077 Jump between original kernel and kexeced kernel and invoke
2078 code in physical address mode via KEXEC
2080 config PHYSICAL_START
2081 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
2084 This gives the physical address where the kernel is loaded.
2086 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
2087 bzImage will decompress itself to above physical address and
2088 run from there. Otherwise, bzImage will run from the address where
2089 it has been loaded by the boot loader and will ignore above physical
2092 In normal kdump cases one does not have to set/change this option
2093 as now bzImage can be compiled as a completely relocatable image
2094 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
2095 address. This option is mainly useful for the folks who don't want
2096 to use a bzImage for capturing the crash dump and want to use a
2097 vmlinux instead. vmlinux is not relocatable hence a kernel needs
2098 to be specifically compiled to run from a specific memory area
2099 (normally a reserved region) and this option comes handy.
2101 So if you are using bzImage for capturing the crash dump,
2102 leave the value here unchanged to 0x1000000 and set
2103 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
2104 for capturing the crash dump change this value to start of
2105 the reserved region. In other words, it can be set based on
2106 the "X" value as specified in the "crashkernel=YM@XM"
2107 command line boot parameter passed to the panic-ed
2108 kernel. Please take a look at Documentation/admin-guide/kdump/kdump.rst
2109 for more details about crash dumps.
2111 Usage of bzImage for capturing the crash dump is recommended as
2112 one does not have to build two kernels. Same kernel can be used
2113 as production kernel and capture kernel. Above option should have
2114 gone away after relocatable bzImage support is introduced. But it
2115 is present because there are users out there who continue to use
2116 vmlinux for dump capture. This option should go away down the
2119 Don't change this unless you know what you are doing.
2122 bool "Build a relocatable kernel"
2125 This builds a kernel image that retains relocation information
2126 so it can be loaded someplace besides the default 1MB.
2127 The relocations tend to make the kernel binary about 10% larger,
2128 but are discarded at runtime.
2130 One use is for the kexec on panic case where the recovery kernel
2131 must live at a different physical address than the primary
2134 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
2135 it has been loaded at and the compile time physical address
2136 (CONFIG_PHYSICAL_START) is used as the minimum location.
2138 config RANDOMIZE_BASE
2139 bool "Randomize the address of the kernel image (KASLR)"
2140 depends on RELOCATABLE
2143 In support of Kernel Address Space Layout Randomization (KASLR),
2144 this randomizes the physical address at which the kernel image
2145 is decompressed and the virtual address where the kernel
2146 image is mapped, as a security feature that deters exploit
2147 attempts relying on knowledge of the location of kernel
2150 On 64-bit, the kernel physical and virtual addresses are
2151 randomized separately. The physical address will be anywhere
2152 between 16MB and the top of physical memory (up to 64TB). The
2153 virtual address will be randomized from 16MB up to 1GB (9 bits
2154 of entropy). Note that this also reduces the memory space
2155 available to kernel modules from 1.5GB to 1GB.
2157 On 32-bit, the kernel physical and virtual addresses are
2158 randomized together. They will be randomized from 16MB up to
2159 512MB (8 bits of entropy).
2161 Entropy is generated using the RDRAND instruction if it is
2162 supported. If RDTSC is supported, its value is mixed into
2163 the entropy pool as well. If neither RDRAND nor RDTSC are
2164 supported, then entropy is read from the i8254 timer. The
2165 usable entropy is limited by the kernel being built using
2166 2GB addressing, and that PHYSICAL_ALIGN must be at a
2167 minimum of 2MB. As a result, only 10 bits of entropy are
2168 theoretically possible, but the implementations are further
2169 limited due to memory layouts.
2173 # Relocation on x86 needs some additional build support
2174 config X86_NEED_RELOCS
2176 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
2178 config PHYSICAL_ALIGN
2179 hex "Alignment value to which kernel should be aligned"
2181 range 0x2000 0x1000000 if X86_32
2182 range 0x200000 0x1000000 if X86_64
2184 This value puts the alignment restrictions on physical address
2185 where kernel is loaded and run from. Kernel is compiled for an
2186 address which meets above alignment restriction.
2188 If bootloader loads the kernel at a non-aligned address and
2189 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
2190 address aligned to above value and run from there.
2192 If bootloader loads the kernel at a non-aligned address and
2193 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
2194 load address and decompress itself to the address it has been
2195 compiled for and run from there. The address for which kernel is
2196 compiled already meets above alignment restrictions. Hence the
2197 end result is that kernel runs from a physical address meeting
2198 above alignment restrictions.
2200 On 32-bit this value must be a multiple of 0x2000. On 64-bit
2201 this value must be a multiple of 0x200000.
2203 Don't change this unless you know what you are doing.
2205 config DYNAMIC_MEMORY_LAYOUT
2208 This option makes base addresses of vmalloc and vmemmap as well as
2209 __PAGE_OFFSET movable during boot.
2211 config RANDOMIZE_MEMORY
2212 bool "Randomize the kernel memory sections"
2214 depends on RANDOMIZE_BASE
2215 select DYNAMIC_MEMORY_LAYOUT
2216 default RANDOMIZE_BASE
2218 Randomizes the base virtual address of kernel memory sections
2219 (physical memory mapping, vmalloc & vmemmap). This security feature
2220 makes exploits relying on predictable memory locations less reliable.
2222 The order of allocations remains unchanged. Entropy is generated in
2223 the same way as RANDOMIZE_BASE. Current implementation in the optimal
2224 configuration have in average 30,000 different possible virtual
2225 addresses for each memory section.
2229 config RANDOMIZE_MEMORY_PHYSICAL_PADDING
2230 hex "Physical memory mapping padding" if EXPERT
2231 depends on RANDOMIZE_MEMORY
2232 default "0xa" if MEMORY_HOTPLUG
2234 range 0x1 0x40 if MEMORY_HOTPLUG
2237 Define the padding in terabytes added to the existing physical
2238 memory size during kernel memory randomization. It is useful
2239 for memory hotplug support but reduces the entropy available for
2240 address randomization.
2242 If unsure, leave at the default value.
2248 config BOOTPARAM_HOTPLUG_CPU0
2249 bool "Set default setting of cpu0_hotpluggable"
2250 depends on HOTPLUG_CPU
2252 Set whether default state of cpu0_hotpluggable is on or off.
2254 Say Y here to enable CPU0 hotplug by default. If this switch
2255 is turned on, there is no need to give cpu0_hotplug kernel
2256 parameter and the CPU0 hotplug feature is enabled by default.
2258 Please note: there are two known CPU0 dependencies if you want
2259 to enable the CPU0 hotplug feature either by this switch or by
2260 cpu0_hotplug kernel parameter.
2262 First, resume from hibernate or suspend always starts from CPU0.
2263 So hibernate and suspend are prevented if CPU0 is offline.
2265 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
2266 offline if any interrupt can not migrate out of CPU0. There may
2267 be other CPU0 dependencies.
2269 Please make sure the dependencies are under your control before
2270 you enable this feature.
2272 Say N if you don't want to enable CPU0 hotplug feature by default.
2273 You still can enable the CPU0 hotplug feature at boot by kernel
2274 parameter cpu0_hotplug.
2276 config DEBUG_HOTPLUG_CPU0
2278 prompt "Debug CPU0 hotplug"
2279 depends on HOTPLUG_CPU
2281 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
2282 soon as possible and boots up userspace with CPU0 offlined. User
2283 can online CPU0 back after boot time.
2285 To debug CPU0 hotplug, you need to enable CPU0 offline/online
2286 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
2287 compilation or giving cpu0_hotplug kernel parameter at boot.
2293 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
2294 depends on COMPAT_32
2296 Certain buggy versions of glibc will crash if they are
2297 presented with a 32-bit vDSO that is not mapped at the address
2298 indicated in its segment table.
2300 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
2301 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
2302 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
2303 the only released version with the bug, but OpenSUSE 9
2304 contains a buggy "glibc 2.3.2".
2306 The symptom of the bug is that everything crashes on startup, saying:
2307 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
2309 Saying Y here changes the default value of the vdso32 boot
2310 option from 1 to 0, which turns off the 32-bit vDSO entirely.
2311 This works around the glibc bug but hurts performance.
2313 If unsure, say N: if you are compiling your own kernel, you
2314 are unlikely to be using a buggy version of glibc.
2317 prompt "vsyscall table for legacy applications"
2319 default LEGACY_VSYSCALL_XONLY
2321 Legacy user code that does not know how to find the vDSO expects
2322 to be able to issue three syscalls by calling fixed addresses in
2323 kernel space. Since this location is not randomized with ASLR,
2324 it can be used to assist security vulnerability exploitation.
2326 This setting can be changed at boot time via the kernel command
2327 line parameter vsyscall=[emulate|xonly|none].
2329 On a system with recent enough glibc (2.14 or newer) and no
2330 static binaries, you can say None without a performance penalty
2331 to improve security.
2333 If unsure, select "Emulate execution only".
2335 config LEGACY_VSYSCALL_EMULATE
2336 bool "Full emulation"
2338 The kernel traps and emulates calls into the fixed vsyscall
2339 address mapping. This makes the mapping non-executable, but
2340 it still contains readable known contents, which could be
2341 used in certain rare security vulnerability exploits. This
2342 configuration is recommended when using legacy userspace
2343 that still uses vsyscalls along with legacy binary
2344 instrumentation tools that require code to be readable.
2346 An example of this type of legacy userspace is running
2347 Pin on an old binary that still uses vsyscalls.
2349 config LEGACY_VSYSCALL_XONLY
2350 bool "Emulate execution only"
2352 The kernel traps and emulates calls into the fixed vsyscall
2353 address mapping and does not allow reads. This
2354 configuration is recommended when userspace might use the
2355 legacy vsyscall area but support for legacy binary
2356 instrumentation of legacy code is not needed. It mitigates
2357 certain uses of the vsyscall area as an ASLR-bypassing
2360 config LEGACY_VSYSCALL_NONE
2363 There will be no vsyscall mapping at all. This will
2364 eliminate any risk of ASLR bypass due to the vsyscall
2365 fixed address mapping. Attempts to use the vsyscalls
2366 will be reported to dmesg, so that either old or
2367 malicious userspace programs can be identified.
2372 bool "Built-in kernel command line"
2374 Allow for specifying boot arguments to the kernel at
2375 build time. On some systems (e.g. embedded ones), it is
2376 necessary or convenient to provide some or all of the
2377 kernel boot arguments with the kernel itself (that is,
2378 to not rely on the boot loader to provide them.)
2380 To compile command line arguments into the kernel,
2381 set this option to 'Y', then fill in the
2382 boot arguments in CONFIG_CMDLINE.
2384 Systems with fully functional boot loaders (i.e. non-embedded)
2385 should leave this option set to 'N'.
2388 string "Built-in kernel command string"
2389 depends on CMDLINE_BOOL
2392 Enter arguments here that should be compiled into the kernel
2393 image and used at boot time. If the boot loader provides a
2394 command line at boot time, it is appended to this string to
2395 form the full kernel command line, when the system boots.
2397 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
2398 change this behavior.
2400 In most cases, the command line (whether built-in or provided
2401 by the boot loader) should specify the device for the root
2404 config CMDLINE_OVERRIDE
2405 bool "Built-in command line overrides boot loader arguments"
2406 depends on CMDLINE_BOOL && CMDLINE != ""
2408 Set this option to 'Y' to have the kernel ignore the boot loader
2409 command line, and use ONLY the built-in command line.
2411 This is used to work around broken boot loaders. This should
2412 be set to 'N' under normal conditions.
2414 config MODIFY_LDT_SYSCALL
2415 bool "Enable the LDT (local descriptor table)" if EXPERT
2418 Linux can allow user programs to install a per-process x86
2419 Local Descriptor Table (LDT) using the modify_ldt(2) system
2420 call. This is required to run 16-bit or segmented code such as
2421 DOSEMU or some Wine programs. It is also used by some very old
2422 threading libraries.
2424 Enabling this feature adds a small amount of overhead to
2425 context switches and increases the low-level kernel attack
2426 surface. Disabling it removes the modify_ldt(2) system call.
2428 Saying 'N' here may make sense for embedded or server kernels.
2430 source "kernel/livepatch/Kconfig"
2434 config ARCH_HAS_ADD_PAGES
2436 depends on X86_64 && ARCH_ENABLE_MEMORY_HOTPLUG
2438 config ARCH_ENABLE_MEMORY_HOTPLUG
2440 depends on X86_64 || (X86_32 && HIGHMEM)
2442 config ARCH_ENABLE_MEMORY_HOTREMOVE
2444 depends on MEMORY_HOTPLUG
2446 config USE_PERCPU_NUMA_NODE_ID
2450 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
2452 depends on X86_64 || X86_PAE
2454 config ARCH_ENABLE_HUGEPAGE_MIGRATION
2456 depends on X86_64 && HUGETLB_PAGE && MIGRATION
2458 config ARCH_ENABLE_THP_MIGRATION
2460 depends on X86_64 && TRANSPARENT_HUGEPAGE
2462 menu "Power management and ACPI options"
2464 config ARCH_HIBERNATION_HEADER
2466 depends on HIBERNATION
2468 source "kernel/power/Kconfig"
2470 source "drivers/acpi/Kconfig"
2472 source "drivers/sfi/Kconfig"
2479 tristate "APM (Advanced Power Management) BIOS support"
2480 depends on X86_32 && PM_SLEEP
2482 APM is a BIOS specification for saving power using several different
2483 techniques. This is mostly useful for battery powered laptops with
2484 APM compliant BIOSes. If you say Y here, the system time will be
2485 reset after a RESUME operation, the /proc/apm device will provide
2486 battery status information, and user-space programs will receive
2487 notification of APM "events" (e.g. battery status change).
2489 If you select "Y" here, you can disable actual use of the APM
2490 BIOS by passing the "apm=off" option to the kernel at boot time.
2492 Note that the APM support is almost completely disabled for
2493 machines with more than one CPU.
2495 In order to use APM, you will need supporting software. For location
2496 and more information, read <file:Documentation/power/apm-acpi.rst>
2497 and the Battery Powered Linux mini-HOWTO, available from
2498 <http://www.tldp.org/docs.html#howto>.
2500 This driver does not spin down disk drives (see the hdparm(8)
2501 manpage ("man 8 hdparm") for that), and it doesn't turn off
2502 VESA-compliant "green" monitors.
2504 This driver does not support the TI 4000M TravelMate and the ACER
2505 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2506 desktop machines also don't have compliant BIOSes, and this driver
2507 may cause those machines to panic during the boot phase.
2509 Generally, if you don't have a battery in your machine, there isn't
2510 much point in using this driver and you should say N. If you get
2511 random kernel OOPSes or reboots that don't seem to be related to
2512 anything, try disabling/enabling this option (or disabling/enabling
2515 Some other things you should try when experiencing seemingly random,
2518 1) make sure that you have enough swap space and that it is
2520 2) pass the "no-hlt" option to the kernel
2521 3) switch on floating point emulation in the kernel and pass
2522 the "no387" option to the kernel
2523 4) pass the "floppy=nodma" option to the kernel
2524 5) pass the "mem=4M" option to the kernel (thereby disabling
2525 all but the first 4 MB of RAM)
2526 6) make sure that the CPU is not over clocked.
2527 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2528 8) disable the cache from your BIOS settings
2529 9) install a fan for the video card or exchange video RAM
2530 10) install a better fan for the CPU
2531 11) exchange RAM chips
2532 12) exchange the motherboard.
2534 To compile this driver as a module, choose M here: the
2535 module will be called apm.
2539 config APM_IGNORE_USER_SUSPEND
2540 bool "Ignore USER SUSPEND"
2542 This option will ignore USER SUSPEND requests. On machines with a
2543 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2544 series notebooks, it is necessary to say Y because of a BIOS bug.
2546 config APM_DO_ENABLE
2547 bool "Enable PM at boot time"
2549 Enable APM features at boot time. From page 36 of the APM BIOS
2550 specification: "When disabled, the APM BIOS does not automatically
2551 power manage devices, enter the Standby State, enter the Suspend
2552 State, or take power saving steps in response to CPU Idle calls."
2553 This driver will make CPU Idle calls when Linux is idle (unless this
2554 feature is turned off -- see "Do CPU IDLE calls", below). This
2555 should always save battery power, but more complicated APM features
2556 will be dependent on your BIOS implementation. You may need to turn
2557 this option off if your computer hangs at boot time when using APM
2558 support, or if it beeps continuously instead of suspending. Turn
2559 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2560 T400CDT. This is off by default since most machines do fine without
2565 bool "Make CPU Idle calls when idle"
2567 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2568 On some machines, this can activate improved power savings, such as
2569 a slowed CPU clock rate, when the machine is idle. These idle calls
2570 are made after the idle loop has run for some length of time (e.g.,
2571 333 mS). On some machines, this will cause a hang at boot time or
2572 whenever the CPU becomes idle. (On machines with more than one CPU,
2573 this option does nothing.)
2575 config APM_DISPLAY_BLANK
2576 bool "Enable console blanking using APM"
2578 Enable console blanking using the APM. Some laptops can use this to
2579 turn off the LCD backlight when the screen blanker of the Linux
2580 virtual console blanks the screen. Note that this is only used by
2581 the virtual console screen blanker, and won't turn off the backlight
2582 when using the X Window system. This also doesn't have anything to
2583 do with your VESA-compliant power-saving monitor. Further, this
2584 option doesn't work for all laptops -- it might not turn off your
2585 backlight at all, or it might print a lot of errors to the console,
2586 especially if you are using gpm.
2588 config APM_ALLOW_INTS
2589 bool "Allow interrupts during APM BIOS calls"
2591 Normally we disable external interrupts while we are making calls to
2592 the APM BIOS as a measure to lessen the effects of a badly behaving
2593 BIOS implementation. The BIOS should reenable interrupts if it
2594 needs to. Unfortunately, some BIOSes do not -- especially those in
2595 many of the newer IBM Thinkpads. If you experience hangs when you
2596 suspend, try setting this to Y. Otherwise, say N.
2600 source "drivers/cpufreq/Kconfig"
2602 source "drivers/cpuidle/Kconfig"
2604 source "drivers/idle/Kconfig"
2609 menu "Bus options (PCI etc.)"
2612 prompt "PCI access mode"
2613 depends on X86_32 && PCI
2616 On PCI systems, the BIOS can be used to detect the PCI devices and
2617 determine their configuration. However, some old PCI motherboards
2618 have BIOS bugs and may crash if this is done. Also, some embedded
2619 PCI-based systems don't have any BIOS at all. Linux can also try to
2620 detect the PCI hardware directly without using the BIOS.
2622 With this option, you can specify how Linux should detect the
2623 PCI devices. If you choose "BIOS", the BIOS will be used,
2624 if you choose "Direct", the BIOS won't be used, and if you
2625 choose "MMConfig", then PCI Express MMCONFIG will be used.
2626 If you choose "Any", the kernel will try MMCONFIG, then the
2627 direct access method and falls back to the BIOS if that doesn't
2628 work. If unsure, go with the default, which is "Any".
2633 config PCI_GOMMCONFIG
2650 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2652 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2655 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2658 bool "Support mmconfig PCI config space access" if X86_64
2660 depends on PCI && (ACPI || SFI || JAILHOUSE_GUEST)
2661 depends on X86_64 || (PCI_GOANY || PCI_GOMMCONFIG)
2665 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2669 depends on PCI && XEN
2672 config MMCONF_FAM10H
2674 depends on X86_64 && PCI_MMCONFIG && ACPI
2676 config PCI_CNB20LE_QUIRK
2677 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2680 Read the PCI windows out of the CNB20LE host bridge. This allows
2681 PCI hotplug to work on systems with the CNB20LE chipset which do
2684 There's no public spec for this chipset, and this functionality
2685 is known to be incomplete.
2687 You should say N unless you know you need this.
2690 bool "ISA bus support on modern systems" if EXPERT
2692 Expose ISA bus device drivers and options available for selection and
2693 configuration. Enable this option if your target machine has an ISA
2694 bus. ISA is an older system, displaced by PCI and newer bus
2695 architectures -- if your target machine is modern, it probably does
2696 not have an ISA bus.
2700 # x86_64 have no ISA slots, but can have ISA-style DMA.
2702 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2705 Enables ISA-style DMA support for devices requiring such controllers.
2713 Find out whether you have ISA slots on your motherboard. ISA is the
2714 name of a bus system, i.e. the way the CPU talks to the other stuff
2715 inside your box. Other bus systems are PCI, EISA, MicroChannel
2716 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2717 newer boards don't support it. If you have ISA, say Y, otherwise N.
2720 tristate "NatSemi SCx200 support"
2722 This provides basic support for National Semiconductor's
2723 (now AMD's) Geode processors. The driver probes for the
2724 PCI-IDs of several on-chip devices, so its a good dependency
2725 for other scx200_* drivers.
2727 If compiled as a module, the driver is named scx200.
2729 config SCx200HR_TIMER
2730 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2734 This driver provides a clocksource built upon the on-chip
2735 27MHz high-resolution timer. Its also a workaround for
2736 NSC Geode SC-1100's buggy TSC, which loses time when the
2737 processor goes idle (as is done by the scheduler). The
2738 other workaround is idle=poll boot option.
2741 bool "One Laptop Per Child support"
2749 Add support for detecting the unique features of the OLPC
2753 bool "OLPC XO-1 Power Management"
2754 depends on OLPC && MFD_CS5535=y && PM_SLEEP
2756 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2759 bool "OLPC XO-1 Real Time Clock"
2760 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2762 Add support for the XO-1 real time clock, which can be used as a
2763 programmable wakeup source.
2766 bool "OLPC XO-1 SCI extras"
2767 depends on OLPC && OLPC_XO1_PM && GPIO_CS5535=y
2771 Add support for SCI-based features of the OLPC XO-1 laptop:
2772 - EC-driven system wakeups
2776 - AC adapter status updates
2777 - Battery status updates
2779 config OLPC_XO15_SCI
2780 bool "OLPC XO-1.5 SCI extras"
2781 depends on OLPC && ACPI
2784 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2785 - EC-driven system wakeups
2786 - AC adapter status updates
2787 - Battery status updates
2790 bool "PCEngines ALIX System Support (LED setup)"
2793 This option enables system support for the PCEngines ALIX.
2794 At present this just sets up LEDs for GPIO control on
2795 ALIX2/3/6 boards. However, other system specific setup should
2798 Note: You must still enable the drivers for GPIO and LED support
2799 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2801 Note: You have to set alix.force=1 for boards with Award BIOS.
2804 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2807 This option enables system support for the Soekris Engineering net5501.
2810 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2814 This option enables system support for the Traverse Technologies GEOS.
2817 bool "Technologic Systems TS-5500 platform support"
2819 select CHECK_SIGNATURE
2823 This option enables system support for the Technologic Systems TS-5500.
2829 depends on CPU_SUP_AMD && PCI
2832 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2834 Firmwares often provide initial graphics framebuffers so the BIOS,
2835 bootloader or kernel can show basic video-output during boot for
2836 user-guidance and debugging. Historically, x86 used the VESA BIOS
2837 Extensions and EFI-framebuffers for this, which are mostly limited
2839 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2840 framebuffers so the new generic system-framebuffer drivers can be
2841 used on x86. If the framebuffer is not compatible with the generic
2842 modes, it is advertised as fallback platform framebuffer so legacy
2843 drivers like efifb, vesafb and uvesafb can pick it up.
2844 If this option is not selected, all system framebuffers are always
2845 marked as fallback platform framebuffers as usual.
2847 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2848 not be able to pick up generic system framebuffers if this option
2849 is selected. You are highly encouraged to enable simplefb as
2850 replacement if you select this option. simplefb can correctly deal
2851 with generic system framebuffers. But you should still keep vesafb
2852 and others enabled as fallback if a system framebuffer is
2853 incompatible with simplefb.
2860 menu "Binary Emulations"
2862 config IA32_EMULATION
2863 bool "IA32 Emulation"
2865 select ARCH_WANT_OLD_COMPAT_IPC
2867 select COMPAT_BINFMT_ELF
2868 select COMPAT_OLD_SIGACTION
2870 Include code to run legacy 32-bit programs under a
2871 64-bit kernel. You should likely turn this on, unless you're
2872 100% sure that you don't have any 32-bit programs left.
2875 tristate "IA32 a.out support"
2876 depends on IA32_EMULATION
2879 Support old a.out binaries in the 32bit emulation.
2882 bool "x32 ABI for 64-bit mode"
2885 Include code to run binaries for the x32 native 32-bit ABI
2886 for 64-bit processors. An x32 process gets access to the
2887 full 64-bit register file and wide data path while leaving
2888 pointers at 32 bits for smaller memory footprint.
2890 You will need a recent binutils (2.22 or later) with
2891 elf32_x86_64 support enabled to compile a kernel with this
2896 depends on IA32_EMULATION || X86_32
2898 select OLD_SIGSUSPEND3
2902 depends on IA32_EMULATION || X86_X32
2905 config COMPAT_FOR_U64_ALIGNMENT
2908 config SYSVIPC_COMPAT
2916 config HAVE_ATOMIC_IOMAP
2920 source "drivers/firmware/Kconfig"
2922 source "arch/x86/kvm/Kconfig"
2924 source "arch/x86/Kconfig.assembler"