sched: stop the unbound recursion in preempt_schedule_context()
[deliverable/linux.git] / arch / x86 / Kconfig
1 # Select 32 or 64 bit
2 config 64BIT
3 bool "64-bit kernel" if ARCH = "x86"
4 default ARCH != "i386"
5 ---help---
6 Say yes to build a 64-bit kernel - formerly known as x86_64
7 Say no to build a 32-bit kernel - formerly known as i386
8
9 config X86_32
10 def_bool y
11 depends on !64BIT
12 select CLKSRC_I8253
13 select HAVE_UID16
14
15 config X86_64
16 def_bool y
17 depends on 64BIT
18 select X86_DEV_DMA_OPS
19 select ARCH_USE_CMPXCHG_LOCKREF
20
21 ### Arch settings
22 config X86
23 def_bool y
24 select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
25 select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
26 select ARCH_HAS_FAST_MULTIPLIER
27 select ARCH_MIGHT_HAVE_PC_PARPORT
28 select ARCH_MIGHT_HAVE_PC_SERIO
29 select HAVE_AOUT if X86_32
30 select HAVE_UNSTABLE_SCHED_CLOCK
31 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
32 select ARCH_SUPPORTS_INT128 if X86_64
33 select HAVE_IDE
34 select HAVE_OPROFILE
35 select HAVE_PCSPKR_PLATFORM
36 select HAVE_PERF_EVENTS
37 select HAVE_IOREMAP_PROT
38 select HAVE_KPROBES
39 select HAVE_MEMBLOCK
40 select HAVE_MEMBLOCK_NODE_MAP
41 select ARCH_DISCARD_MEMBLOCK
42 select ARCH_WANT_OPTIONAL_GPIOLIB
43 select ARCH_WANT_FRAME_POINTERS
44 select HAVE_DMA_ATTRS
45 select HAVE_DMA_CONTIGUOUS
46 select HAVE_KRETPROBES
47 select GENERIC_EARLY_IOREMAP
48 select HAVE_OPTPROBES
49 select HAVE_KPROBES_ON_FTRACE
50 select HAVE_FTRACE_MCOUNT_RECORD
51 select HAVE_FENTRY if X86_64
52 select HAVE_C_RECORDMCOUNT
53 select HAVE_DYNAMIC_FTRACE
54 select HAVE_DYNAMIC_FTRACE_WITH_REGS
55 select HAVE_FUNCTION_TRACER
56 select HAVE_FUNCTION_GRAPH_TRACER
57 select HAVE_FUNCTION_GRAPH_FP_TEST
58 select HAVE_SYSCALL_TRACEPOINTS
59 select SYSCTL_EXCEPTION_TRACE
60 select HAVE_KVM
61 select HAVE_ARCH_KGDB
62 select HAVE_ARCH_TRACEHOOK
63 select HAVE_GENERIC_DMA_COHERENT if X86_32
64 select HAVE_EFFICIENT_UNALIGNED_ACCESS
65 select USER_STACKTRACE_SUPPORT
66 select HAVE_REGS_AND_STACK_ACCESS_API
67 select HAVE_DMA_API_DEBUG
68 select HAVE_KERNEL_GZIP
69 select HAVE_KERNEL_BZIP2
70 select HAVE_KERNEL_LZMA
71 select HAVE_KERNEL_XZ
72 select HAVE_KERNEL_LZO
73 select HAVE_KERNEL_LZ4
74 select HAVE_HW_BREAKPOINT
75 select HAVE_MIXED_BREAKPOINTS_REGS
76 select PERF_EVENTS
77 select HAVE_PERF_EVENTS_NMI
78 select HAVE_PERF_REGS
79 select HAVE_PERF_USER_STACK_DUMP
80 select HAVE_DEBUG_KMEMLEAK
81 select ANON_INODES
82 select HAVE_ALIGNED_STRUCT_PAGE if SLUB
83 select HAVE_CMPXCHG_LOCAL
84 select HAVE_CMPXCHG_DOUBLE
85 select HAVE_ARCH_KMEMCHECK
86 select HAVE_USER_RETURN_NOTIFIER
87 select ARCH_BINFMT_ELF_RANDOMIZE_PIE
88 select HAVE_ARCH_JUMP_LABEL
89 select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
90 select SPARSE_IRQ
91 select GENERIC_FIND_FIRST_BIT
92 select GENERIC_IRQ_PROBE
93 select GENERIC_PENDING_IRQ if SMP
94 select GENERIC_IRQ_SHOW
95 select GENERIC_CLOCKEVENTS_MIN_ADJUST
96 select IRQ_FORCED_THREADING
97 select HAVE_BPF_JIT if X86_64
98 select HAVE_ARCH_TRANSPARENT_HUGEPAGE
99 select ARCH_HAS_SG_CHAIN
100 select CLKEVT_I8253
101 select ARCH_HAVE_NMI_SAFE_CMPXCHG
102 select GENERIC_IOMAP
103 select DCACHE_WORD_ACCESS
104 select GENERIC_SMP_IDLE_THREAD
105 select ARCH_WANT_IPC_PARSE_VERSION if X86_32
106 select HAVE_ARCH_SECCOMP_FILTER
107 select BUILDTIME_EXTABLE_SORT
108 select GENERIC_CMOS_UPDATE
109 select HAVE_ARCH_SOFT_DIRTY if X86_64
110 select CLOCKSOURCE_WATCHDOG
111 select GENERIC_CLOCKEVENTS
112 select ARCH_CLOCKSOURCE_DATA
113 select CLOCKSOURCE_VALIDATE_LAST_CYCLE
114 select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
115 select GENERIC_TIME_VSYSCALL
116 select GENERIC_STRNCPY_FROM_USER
117 select GENERIC_STRNLEN_USER
118 select HAVE_CONTEXT_TRACKING if X86_64
119 select HAVE_IRQ_TIME_ACCOUNTING
120 select VIRT_TO_BUS
121 select MODULES_USE_ELF_REL if X86_32
122 select MODULES_USE_ELF_RELA if X86_64
123 select CLONE_BACKWARDS if X86_32
124 select ARCH_USE_BUILTIN_BSWAP
125 select ARCH_USE_QUEUE_RWLOCK
126 select OLD_SIGSUSPEND3 if X86_32 || IA32_EMULATION
127 select OLD_SIGACTION if X86_32
128 select COMPAT_OLD_SIGACTION if IA32_EMULATION
129 select RTC_LIB
130 select HAVE_DEBUG_STACKOVERFLOW
131 select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
132 select HAVE_CC_STACKPROTECTOR
133 select GENERIC_CPU_AUTOPROBE
134 select HAVE_ARCH_AUDITSYSCALL
135 select ARCH_SUPPORTS_ATOMIC_RMW
136 select HAVE_ACPI_APEI if ACPI
137 select HAVE_ACPI_APEI_NMI if ACPI
138 select ACPI_LEGACY_TABLES_LOOKUP if ACPI
139 select X86_FEATURE_NAMES if PROC_FS
140
141 config INSTRUCTION_DECODER
142 def_bool y
143 depends on KPROBES || PERF_EVENTS || UPROBES
144
145 config OUTPUT_FORMAT
146 string
147 default "elf32-i386" if X86_32
148 default "elf64-x86-64" if X86_64
149
150 config ARCH_DEFCONFIG
151 string
152 default "arch/x86/configs/i386_defconfig" if X86_32
153 default "arch/x86/configs/x86_64_defconfig" if X86_64
154
155 config LOCKDEP_SUPPORT
156 def_bool y
157
158 config STACKTRACE_SUPPORT
159 def_bool y
160
161 config HAVE_LATENCYTOP_SUPPORT
162 def_bool y
163
164 config MMU
165 def_bool y
166
167 config SBUS
168 bool
169
170 config NEED_DMA_MAP_STATE
171 def_bool y
172 depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
173
174 config NEED_SG_DMA_LENGTH
175 def_bool y
176
177 config GENERIC_ISA_DMA
178 def_bool y
179 depends on ISA_DMA_API
180
181 config GENERIC_BUG
182 def_bool y
183 depends on BUG
184 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
185
186 config GENERIC_BUG_RELATIVE_POINTERS
187 bool
188
189 config GENERIC_HWEIGHT
190 def_bool y
191
192 config ARCH_MAY_HAVE_PC_FDC
193 def_bool y
194 depends on ISA_DMA_API
195
196 config RWSEM_XCHGADD_ALGORITHM
197 def_bool y
198
199 config GENERIC_CALIBRATE_DELAY
200 def_bool y
201
202 config ARCH_HAS_CPU_RELAX
203 def_bool y
204
205 config ARCH_HAS_CACHE_LINE_SIZE
206 def_bool y
207
208 config HAVE_SETUP_PER_CPU_AREA
209 def_bool y
210
211 config NEED_PER_CPU_EMBED_FIRST_CHUNK
212 def_bool y
213
214 config NEED_PER_CPU_PAGE_FIRST_CHUNK
215 def_bool y
216
217 config ARCH_HIBERNATION_POSSIBLE
218 def_bool y
219
220 config ARCH_SUSPEND_POSSIBLE
221 def_bool y
222
223 config ARCH_WANT_HUGE_PMD_SHARE
224 def_bool y
225
226 config ARCH_WANT_GENERAL_HUGETLB
227 def_bool y
228
229 config ZONE_DMA32
230 bool
231 default X86_64
232
233 config AUDIT_ARCH
234 bool
235 default X86_64
236
237 config ARCH_SUPPORTS_OPTIMIZED_INLINING
238 def_bool y
239
240 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
241 def_bool y
242
243 config HAVE_INTEL_TXT
244 def_bool y
245 depends on INTEL_IOMMU && ACPI
246
247 config X86_32_SMP
248 def_bool y
249 depends on X86_32 && SMP
250
251 config X86_64_SMP
252 def_bool y
253 depends on X86_64 && SMP
254
255 config X86_HT
256 def_bool y
257 depends on SMP
258
259 config X86_32_LAZY_GS
260 def_bool y
261 depends on X86_32 && !CC_STACKPROTECTOR
262
263 config ARCH_HWEIGHT_CFLAGS
264 string
265 default "-fcall-saved-ecx -fcall-saved-edx" if X86_32
266 default "-fcall-saved-rdi -fcall-saved-rsi -fcall-saved-rdx -fcall-saved-rcx -fcall-saved-r8 -fcall-saved-r9 -fcall-saved-r10 -fcall-saved-r11" if X86_64
267
268 config ARCH_SUPPORTS_UPROBES
269 def_bool y
270
271 config FIX_EARLYCON_MEM
272 def_bool y
273
274 source "init/Kconfig"
275 source "kernel/Kconfig.freezer"
276
277 menu "Processor type and features"
278
279 config ZONE_DMA
280 bool "DMA memory allocation support" if EXPERT
281 default y
282 help
283 DMA memory allocation support allows devices with less than 32-bit
284 addressing to allocate within the first 16MB of address space.
285 Disable if no such devices will be used.
286
287 If unsure, say Y.
288
289 config SMP
290 bool "Symmetric multi-processing support"
291 ---help---
292 This enables support for systems with more than one CPU. If you have
293 a system with only one CPU, say N. If you have a system with more
294 than one CPU, say Y.
295
296 If you say N here, the kernel will run on uni- and multiprocessor
297 machines, but will use only one CPU of a multiprocessor machine. If
298 you say Y here, the kernel will run on many, but not all,
299 uniprocessor machines. On a uniprocessor machine, the kernel
300 will run faster if you say N here.
301
302 Note that if you say Y here and choose architecture "586" or
303 "Pentium" under "Processor family", the kernel will not work on 486
304 architectures. Similarly, multiprocessor kernels for the "PPro"
305 architecture may not work on all Pentium based boards.
306
307 People using multiprocessor machines who say Y here should also say
308 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
309 Management" code will be disabled if you say Y here.
310
311 See also <file:Documentation/x86/i386/IO-APIC.txt>,
312 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
313 <http://www.tldp.org/docs.html#howto>.
314
315 If you don't know what to do here, say N.
316
317 config X86_FEATURE_NAMES
318 bool "Processor feature human-readable names" if EMBEDDED
319 default y
320 ---help---
321 This option compiles in a table of x86 feature bits and corresponding
322 names. This is required to support /proc/cpuinfo and a few kernel
323 messages. You can disable this to save space, at the expense of
324 making those few kernel messages show numeric feature bits instead.
325
326 If in doubt, say Y.
327
328 config X86_X2APIC
329 bool "Support x2apic"
330 depends on X86_LOCAL_APIC && X86_64 && IRQ_REMAP
331 ---help---
332 This enables x2apic support on CPUs that have this feature.
333
334 This allows 32-bit apic IDs (so it can support very large systems),
335 and accesses the local apic via MSRs not via mmio.
336
337 If you don't know what to do here, say N.
338
339 config X86_MPPARSE
340 bool "Enable MPS table" if ACPI || SFI
341 default y
342 depends on X86_LOCAL_APIC
343 ---help---
344 For old smp systems that do not have proper acpi support. Newer systems
345 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
346
347 config X86_BIGSMP
348 bool "Support for big SMP systems with more than 8 CPUs"
349 depends on X86_32 && SMP
350 ---help---
351 This option is needed for the systems that have more than 8 CPUs
352
353 config GOLDFISH
354 def_bool y
355 depends on X86_GOLDFISH
356
357 if X86_32
358 config X86_EXTENDED_PLATFORM
359 bool "Support for extended (non-PC) x86 platforms"
360 default y
361 ---help---
362 If you disable this option then the kernel will only support
363 standard PC platforms. (which covers the vast majority of
364 systems out there.)
365
366 If you enable this option then you'll be able to select support
367 for the following (non-PC) 32 bit x86 platforms:
368 Goldfish (Android emulator)
369 AMD Elan
370 RDC R-321x SoC
371 SGI 320/540 (Visual Workstation)
372 STA2X11-based (e.g. Northville)
373 Moorestown MID devices
374
375 If you have one of these systems, or if you want to build a
376 generic distribution kernel, say Y here - otherwise say N.
377 endif
378
379 if X86_64
380 config X86_EXTENDED_PLATFORM
381 bool "Support for extended (non-PC) x86 platforms"
382 default y
383 ---help---
384 If you disable this option then the kernel will only support
385 standard PC platforms. (which covers the vast majority of
386 systems out there.)
387
388 If you enable this option then you'll be able to select support
389 for the following (non-PC) 64 bit x86 platforms:
390 Numascale NumaChip
391 ScaleMP vSMP
392 SGI Ultraviolet
393
394 If you have one of these systems, or if you want to build a
395 generic distribution kernel, say Y here - otherwise say N.
396 endif
397 # This is an alphabetically sorted list of 64 bit extended platforms
398 # Please maintain the alphabetic order if and when there are additions
399 config X86_NUMACHIP
400 bool "Numascale NumaChip"
401 depends on X86_64
402 depends on X86_EXTENDED_PLATFORM
403 depends on NUMA
404 depends on SMP
405 depends on X86_X2APIC
406 depends on PCI_MMCONFIG
407 ---help---
408 Adds support for Numascale NumaChip large-SMP systems. Needed to
409 enable more than ~168 cores.
410 If you don't have one of these, you should say N here.
411
412 config X86_VSMP
413 bool "ScaleMP vSMP"
414 select HYPERVISOR_GUEST
415 select PARAVIRT
416 depends on X86_64 && PCI
417 depends on X86_EXTENDED_PLATFORM
418 depends on SMP
419 ---help---
420 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
421 supposed to run on these EM64T-based machines. Only choose this option
422 if you have one of these machines.
423
424 config X86_UV
425 bool "SGI Ultraviolet"
426 depends on X86_64
427 depends on X86_EXTENDED_PLATFORM
428 depends on NUMA
429 depends on X86_X2APIC
430 ---help---
431 This option is needed in order to support SGI Ultraviolet systems.
432 If you don't have one of these, you should say N here.
433
434 # Following is an alphabetically sorted list of 32 bit extended platforms
435 # Please maintain the alphabetic order if and when there are additions
436
437 config X86_GOLDFISH
438 bool "Goldfish (Virtual Platform)"
439 depends on X86_EXTENDED_PLATFORM
440 ---help---
441 Enable support for the Goldfish virtual platform used primarily
442 for Android development. Unless you are building for the Android
443 Goldfish emulator say N here.
444
445 config X86_INTEL_CE
446 bool "CE4100 TV platform"
447 depends on PCI
448 depends on PCI_GODIRECT
449 depends on X86_IO_APIC
450 depends on X86_32
451 depends on X86_EXTENDED_PLATFORM
452 select X86_REBOOTFIXUPS
453 select OF
454 select OF_EARLY_FLATTREE
455 select IRQ_DOMAIN
456 ---help---
457 Select for the Intel CE media processor (CE4100) SOC.
458 This option compiles in support for the CE4100 SOC for settop
459 boxes and media devices.
460
461 config X86_INTEL_MID
462 bool "Intel MID platform support"
463 depends on X86_32
464 depends on X86_EXTENDED_PLATFORM
465 depends on X86_PLATFORM_DEVICES
466 depends on PCI
467 depends on PCI_GOANY
468 depends on X86_IO_APIC
469 select SFI
470 select I2C
471 select DW_APB_TIMER
472 select APB_TIMER
473 select INTEL_SCU_IPC
474 select MFD_INTEL_MSIC
475 ---help---
476 Select to build a kernel capable of supporting Intel MID (Mobile
477 Internet Device) platform systems which do not have the PCI legacy
478 interfaces. If you are building for a PC class system say N here.
479
480 Intel MID platforms are based on an Intel processor and chipset which
481 consume less power than most of the x86 derivatives.
482
483 config X86_INTEL_LPSS
484 bool "Intel Low Power Subsystem Support"
485 depends on ACPI
486 select COMMON_CLK
487 select PINCTRL
488 ---help---
489 Select to build support for Intel Low Power Subsystem such as
490 found on Intel Lynxpoint PCH. Selecting this option enables
491 things like clock tree (common clock framework) and pincontrol
492 which are needed by the LPSS peripheral drivers.
493
494 config IOSF_MBI
495 tristate "Intel SoC IOSF Sideband support for SoC platforms"
496 depends on PCI
497 ---help---
498 This option enables sideband register access support for Intel SoC
499 platforms. On these platforms the IOSF sideband is used in lieu of
500 MSR's for some register accesses, mostly but not limited to thermal
501 and power. Drivers may query the availability of this device to
502 determine if they need the sideband in order to work on these
503 platforms. The sideband is available on the following SoC products.
504 This list is not meant to be exclusive.
505 - BayTrail
506 - Braswell
507 - Quark
508
509 You should say Y if you are running a kernel on one of these SoC's.
510
511 config IOSF_MBI_DEBUG
512 bool "Enable IOSF sideband access through debugfs"
513 depends on IOSF_MBI && DEBUG_FS
514 ---help---
515 Select this option to expose the IOSF sideband access registers (MCR,
516 MDR, MCRX) through debugfs to write and read register information from
517 different units on the SoC. This is most useful for obtaining device
518 state information for debug and analysis. As this is a general access
519 mechanism, users of this option would have specific knowledge of the
520 device they want to access.
521
522 If you don't require the option or are in doubt, say N.
523
524 config X86_RDC321X
525 bool "RDC R-321x SoC"
526 depends on X86_32
527 depends on X86_EXTENDED_PLATFORM
528 select M486
529 select X86_REBOOTFIXUPS
530 ---help---
531 This option is needed for RDC R-321x system-on-chip, also known
532 as R-8610-(G).
533 If you don't have one of these chips, you should say N here.
534
535 config X86_32_NON_STANDARD
536 bool "Support non-standard 32-bit SMP architectures"
537 depends on X86_32 && SMP
538 depends on X86_EXTENDED_PLATFORM
539 ---help---
540 This option compiles in the bigsmp and STA2X11 default
541 subarchitectures. It is intended for a generic binary
542 kernel. If you select them all, kernel will probe it one by
543 one and will fallback to default.
544
545 # Alphabetically sorted list of Non standard 32 bit platforms
546
547 config X86_SUPPORTS_MEMORY_FAILURE
548 def_bool y
549 # MCE code calls memory_failure():
550 depends on X86_MCE
551 # On 32-bit this adds too big of NODES_SHIFT and we run out of page flags:
552 # On 32-bit SPARSEMEM adds too big of SECTIONS_WIDTH:
553 depends on X86_64 || !SPARSEMEM
554 select ARCH_SUPPORTS_MEMORY_FAILURE
555
556 config STA2X11
557 bool "STA2X11 Companion Chip Support"
558 depends on X86_32_NON_STANDARD && PCI
559 select X86_DEV_DMA_OPS
560 select X86_DMA_REMAP
561 select SWIOTLB
562 select MFD_STA2X11
563 select ARCH_REQUIRE_GPIOLIB
564 default n
565 ---help---
566 This adds support for boards based on the STA2X11 IO-Hub,
567 a.k.a. "ConneXt". The chip is used in place of the standard
568 PC chipset, so all "standard" peripherals are missing. If this
569 option is selected the kernel will still be able to boot on
570 standard PC machines.
571
572 config X86_32_IRIS
573 tristate "Eurobraille/Iris poweroff module"
574 depends on X86_32
575 ---help---
576 The Iris machines from EuroBraille do not have APM or ACPI support
577 to shut themselves down properly. A special I/O sequence is
578 needed to do so, which is what this module does at
579 kernel shutdown.
580
581 This is only for Iris machines from EuroBraille.
582
583 If unused, say N.
584
585 config SCHED_OMIT_FRAME_POINTER
586 def_bool y
587 prompt "Single-depth WCHAN output"
588 depends on X86
589 ---help---
590 Calculate simpler /proc/<PID>/wchan values. If this option
591 is disabled then wchan values will recurse back to the
592 caller function. This provides more accurate wchan values,
593 at the expense of slightly more scheduling overhead.
594
595 If in doubt, say "Y".
596
597 menuconfig HYPERVISOR_GUEST
598 bool "Linux guest support"
599 ---help---
600 Say Y here to enable options for running Linux under various hyper-
601 visors. This option enables basic hypervisor detection and platform
602 setup.
603
604 If you say N, all options in this submenu will be skipped and
605 disabled, and Linux guest support won't be built in.
606
607 if HYPERVISOR_GUEST
608
609 config PARAVIRT
610 bool "Enable paravirtualization code"
611 ---help---
612 This changes the kernel so it can modify itself when it is run
613 under a hypervisor, potentially improving performance significantly
614 over full virtualization. However, when run without a hypervisor
615 the kernel is theoretically slower and slightly larger.
616
617 config PARAVIRT_DEBUG
618 bool "paravirt-ops debugging"
619 depends on PARAVIRT && DEBUG_KERNEL
620 ---help---
621 Enable to debug paravirt_ops internals. Specifically, BUG if
622 a paravirt_op is missing when it is called.
623
624 config PARAVIRT_SPINLOCKS
625 bool "Paravirtualization layer for spinlocks"
626 depends on PARAVIRT && SMP
627 select UNINLINE_SPIN_UNLOCK
628 ---help---
629 Paravirtualized spinlocks allow a pvops backend to replace the
630 spinlock implementation with something virtualization-friendly
631 (for example, block the virtual CPU rather than spinning).
632
633 It has a minimal impact on native kernels and gives a nice performance
634 benefit on paravirtualized KVM / Xen kernels.
635
636 If you are unsure how to answer this question, answer Y.
637
638 source "arch/x86/xen/Kconfig"
639
640 config KVM_GUEST
641 bool "KVM Guest support (including kvmclock)"
642 depends on PARAVIRT
643 select PARAVIRT_CLOCK
644 default y
645 ---help---
646 This option enables various optimizations for running under the KVM
647 hypervisor. It includes a paravirtualized clock, so that instead
648 of relying on a PIT (or probably other) emulation by the
649 underlying device model, the host provides the guest with
650 timing infrastructure such as time of day, and system time
651
652 config KVM_DEBUG_FS
653 bool "Enable debug information for KVM Guests in debugfs"
654 depends on KVM_GUEST && DEBUG_FS
655 default n
656 ---help---
657 This option enables collection of various statistics for KVM guest.
658 Statistics are displayed in debugfs filesystem. Enabling this option
659 may incur significant overhead.
660
661 source "arch/x86/lguest/Kconfig"
662
663 config PARAVIRT_TIME_ACCOUNTING
664 bool "Paravirtual steal time accounting"
665 depends on PARAVIRT
666 default n
667 ---help---
668 Select this option to enable fine granularity task steal time
669 accounting. Time spent executing other tasks in parallel with
670 the current vCPU is discounted from the vCPU power. To account for
671 that, there can be a small performance impact.
672
673 If in doubt, say N here.
674
675 config PARAVIRT_CLOCK
676 bool
677
678 endif #HYPERVISOR_GUEST
679
680 config NO_BOOTMEM
681 def_bool y
682
683 config MEMTEST
684 bool "Memtest"
685 ---help---
686 This option adds a kernel parameter 'memtest', which allows memtest
687 to be set.
688 memtest=0, mean disabled; -- default
689 memtest=1, mean do 1 test pattern;
690 ...
691 memtest=4, mean do 4 test patterns.
692 If you are unsure how to answer this question, answer N.
693
694 source "arch/x86/Kconfig.cpu"
695
696 config HPET_TIMER
697 def_bool X86_64
698 prompt "HPET Timer Support" if X86_32
699 ---help---
700 Use the IA-PC HPET (High Precision Event Timer) to manage
701 time in preference to the PIT and RTC, if a HPET is
702 present.
703 HPET is the next generation timer replacing legacy 8254s.
704 The HPET provides a stable time base on SMP
705 systems, unlike the TSC, but it is more expensive to access,
706 as it is off-chip. You can find the HPET spec at
707 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
708
709 You can safely choose Y here. However, HPET will only be
710 activated if the platform and the BIOS support this feature.
711 Otherwise the 8254 will be used for timing services.
712
713 Choose N to continue using the legacy 8254 timer.
714
715 config HPET_EMULATE_RTC
716 def_bool y
717 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
718
719 config APB_TIMER
720 def_bool y if X86_INTEL_MID
721 prompt "Intel MID APB Timer Support" if X86_INTEL_MID
722 select DW_APB_TIMER
723 depends on X86_INTEL_MID && SFI
724 help
725 APB timer is the replacement for 8254, HPET on X86 MID platforms.
726 The APBT provides a stable time base on SMP
727 systems, unlike the TSC, but it is more expensive to access,
728 as it is off-chip. APB timers are always running regardless of CPU
729 C states, they are used as per CPU clockevent device when possible.
730
731 # Mark as expert because too many people got it wrong.
732 # The code disables itself when not needed.
733 config DMI
734 default y
735 select DMI_SCAN_MACHINE_NON_EFI_FALLBACK
736 bool "Enable DMI scanning" if EXPERT
737 ---help---
738 Enabled scanning of DMI to identify machine quirks. Say Y
739 here unless you have verified that your setup is not
740 affected by entries in the DMI blacklist. Required by PNP
741 BIOS code.
742
743 config GART_IOMMU
744 bool "Old AMD GART IOMMU support"
745 select SWIOTLB
746 depends on X86_64 && PCI && AMD_NB
747 ---help---
748 Provides a driver for older AMD Athlon64/Opteron/Turion/Sempron
749 GART based hardware IOMMUs.
750
751 The GART supports full DMA access for devices with 32-bit access
752 limitations, on systems with more than 3 GB. This is usually needed
753 for USB, sound, many IDE/SATA chipsets and some other devices.
754
755 Newer systems typically have a modern AMD IOMMU, supported via
756 the CONFIG_AMD_IOMMU=y config option.
757
758 In normal configurations this driver is only active when needed:
759 there's more than 3 GB of memory and the system contains a
760 32-bit limited device.
761
762 If unsure, say Y.
763
764 config CALGARY_IOMMU
765 bool "IBM Calgary IOMMU support"
766 select SWIOTLB
767 depends on X86_64 && PCI
768 ---help---
769 Support for hardware IOMMUs in IBM's xSeries x366 and x460
770 systems. Needed to run systems with more than 3GB of memory
771 properly with 32-bit PCI devices that do not support DAC
772 (Double Address Cycle). Calgary also supports bus level
773 isolation, where all DMAs pass through the IOMMU. This
774 prevents them from going anywhere except their intended
775 destination. This catches hard-to-find kernel bugs and
776 mis-behaving drivers and devices that do not use the DMA-API
777 properly to set up their DMA buffers. The IOMMU can be
778 turned off at boot time with the iommu=off parameter.
779 Normally the kernel will make the right choice by itself.
780 If unsure, say Y.
781
782 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
783 def_bool y
784 prompt "Should Calgary be enabled by default?"
785 depends on CALGARY_IOMMU
786 ---help---
787 Should Calgary be enabled by default? if you choose 'y', Calgary
788 will be used (if it exists). If you choose 'n', Calgary will not be
789 used even if it exists. If you choose 'n' and would like to use
790 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
791 If unsure, say Y.
792
793 # need this always selected by IOMMU for the VIA workaround
794 config SWIOTLB
795 def_bool y if X86_64
796 ---help---
797 Support for software bounce buffers used on x86-64 systems
798 which don't have a hardware IOMMU. Using this PCI devices
799 which can only access 32-bits of memory can be used on systems
800 with more than 3 GB of memory.
801 If unsure, say Y.
802
803 config IOMMU_HELPER
804 def_bool y
805 depends on CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU
806
807 config MAXSMP
808 bool "Enable Maximum number of SMP Processors and NUMA Nodes"
809 depends on X86_64 && SMP && DEBUG_KERNEL
810 select CPUMASK_OFFSTACK
811 ---help---
812 Enable maximum number of CPUS and NUMA Nodes for this architecture.
813 If unsure, say N.
814
815 config NR_CPUS
816 int "Maximum number of CPUs" if SMP && !MAXSMP
817 range 2 8 if SMP && X86_32 && !X86_BIGSMP
818 range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
819 range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
820 default "1" if !SMP
821 default "8192" if MAXSMP
822 default "32" if SMP && X86_BIGSMP
823 default "8" if SMP
824 ---help---
825 This allows you to specify the maximum number of CPUs which this
826 kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum
827 supported value is 4096, otherwise the maximum value is 512. The
828 minimum value which makes sense is 2.
829
830 This is purely to save memory - each supported CPU adds
831 approximately eight kilobytes to the kernel image.
832
833 config SCHED_SMT
834 bool "SMT (Hyperthreading) scheduler support"
835 depends on X86_HT
836 ---help---
837 SMT scheduler support improves the CPU scheduler's decision making
838 when dealing with Intel Pentium 4 chips with HyperThreading at a
839 cost of slightly increased overhead in some places. If unsure say
840 N here.
841
842 config SCHED_MC
843 def_bool y
844 prompt "Multi-core scheduler support"
845 depends on X86_HT
846 ---help---
847 Multi-core scheduler support improves the CPU scheduler's decision
848 making when dealing with multi-core CPU chips at a cost of slightly
849 increased overhead in some places. If unsure say N here.
850
851 source "kernel/Kconfig.preempt"
852
853 config X86_UP_APIC
854 bool "Local APIC support on uniprocessors"
855 depends on X86_32 && !SMP && !X86_32_NON_STANDARD && !PCI_MSI
856 ---help---
857 A local APIC (Advanced Programmable Interrupt Controller) is an
858 integrated interrupt controller in the CPU. If you have a single-CPU
859 system which has a processor with a local APIC, you can say Y here to
860 enable and use it. If you say Y here even though your machine doesn't
861 have a local APIC, then the kernel will still run with no slowdown at
862 all. The local APIC supports CPU-generated self-interrupts (timer,
863 performance counters), and the NMI watchdog which detects hard
864 lockups.
865
866 config X86_UP_IOAPIC
867 bool "IO-APIC support on uniprocessors"
868 depends on X86_UP_APIC
869 ---help---
870 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
871 SMP-capable replacement for PC-style interrupt controllers. Most
872 SMP systems and many recent uniprocessor systems have one.
873
874 If you have a single-CPU system with an IO-APIC, you can say Y here
875 to use it. If you say Y here even though your machine doesn't have
876 an IO-APIC, then the kernel will still run with no slowdown at all.
877
878 config X86_LOCAL_APIC
879 def_bool y
880 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC || PCI_MSI
881
882 config X86_IO_APIC
883 def_bool y
884 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_IOAPIC || PCI_MSI
885 select GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
886 select IRQ_DOMAIN
887
888 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
889 bool "Reroute for broken boot IRQs"
890 depends on X86_IO_APIC
891 ---help---
892 This option enables a workaround that fixes a source of
893 spurious interrupts. This is recommended when threaded
894 interrupt handling is used on systems where the generation of
895 superfluous "boot interrupts" cannot be disabled.
896
897 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
898 entry in the chipset's IO-APIC is masked (as, e.g. the RT
899 kernel does during interrupt handling). On chipsets where this
900 boot IRQ generation cannot be disabled, this workaround keeps
901 the original IRQ line masked so that only the equivalent "boot
902 IRQ" is delivered to the CPUs. The workaround also tells the
903 kernel to set up the IRQ handler on the boot IRQ line. In this
904 way only one interrupt is delivered to the kernel. Otherwise
905 the spurious second interrupt may cause the kernel to bring
906 down (vital) interrupt lines.
907
908 Only affects "broken" chipsets. Interrupt sharing may be
909 increased on these systems.
910
911 config X86_MCE
912 bool "Machine Check / overheating reporting"
913 default y
914 ---help---
915 Machine Check support allows the processor to notify the
916 kernel if it detects a problem (e.g. overheating, data corruption).
917 The action the kernel takes depends on the severity of the problem,
918 ranging from warning messages to halting the machine.
919
920 config X86_MCE_INTEL
921 def_bool y
922 prompt "Intel MCE features"
923 depends on X86_MCE && X86_LOCAL_APIC
924 ---help---
925 Additional support for intel specific MCE features such as
926 the thermal monitor.
927
928 config X86_MCE_AMD
929 def_bool y
930 prompt "AMD MCE features"
931 depends on X86_MCE && X86_LOCAL_APIC
932 ---help---
933 Additional support for AMD specific MCE features such as
934 the DRAM Error Threshold.
935
936 config X86_ANCIENT_MCE
937 bool "Support for old Pentium 5 / WinChip machine checks"
938 depends on X86_32 && X86_MCE
939 ---help---
940 Include support for machine check handling on old Pentium 5 or WinChip
941 systems. These typically need to be enabled explicitly on the command
942 line.
943
944 config X86_MCE_THRESHOLD
945 depends on X86_MCE_AMD || X86_MCE_INTEL
946 def_bool y
947
948 config X86_MCE_INJECT
949 depends on X86_MCE
950 tristate "Machine check injector support"
951 ---help---
952 Provide support for injecting machine checks for testing purposes.
953 If you don't know what a machine check is and you don't do kernel
954 QA it is safe to say n.
955
956 config X86_THERMAL_VECTOR
957 def_bool y
958 depends on X86_MCE_INTEL
959
960 config VM86
961 bool "Enable VM86 support" if EXPERT
962 default y
963 depends on X86_32
964 ---help---
965 This option is required by programs like DOSEMU to run
966 16-bit real mode legacy code on x86 processors. It also may
967 be needed by software like XFree86 to initialize some video
968 cards via BIOS. Disabling this option saves about 6K.
969
970 config X86_16BIT
971 bool "Enable support for 16-bit segments" if EXPERT
972 default y
973 ---help---
974 This option is required by programs like Wine to run 16-bit
975 protected mode legacy code on x86 processors. Disabling
976 this option saves about 300 bytes on i386, or around 6K text
977 plus 16K runtime memory on x86-64,
978
979 config X86_ESPFIX32
980 def_bool y
981 depends on X86_16BIT && X86_32
982
983 config X86_ESPFIX64
984 def_bool y
985 depends on X86_16BIT && X86_64
986
987 config TOSHIBA
988 tristate "Toshiba Laptop support"
989 depends on X86_32
990 ---help---
991 This adds a driver to safely access the System Management Mode of
992 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
993 not work on models with a Phoenix BIOS. The System Management Mode
994 is used to set the BIOS and power saving options on Toshiba portables.
995
996 For information on utilities to make use of this driver see the
997 Toshiba Linux utilities web site at:
998 <http://www.buzzard.org.uk/toshiba/>.
999
1000 Say Y if you intend to run this kernel on a Toshiba portable.
1001 Say N otherwise.
1002
1003 config I8K
1004 tristate "Dell laptop support"
1005 select HWMON
1006 ---help---
1007 This adds a driver to safely access the System Management Mode
1008 of the CPU on the Dell Inspiron 8000. The System Management Mode
1009 is used to read cpu temperature and cooling fan status and to
1010 control the fans on the I8K portables.
1011
1012 This driver has been tested only on the Inspiron 8000 but it may
1013 also work with other Dell laptops. You can force loading on other
1014 models by passing the parameter `force=1' to the module. Use at
1015 your own risk.
1016
1017 For information on utilities to make use of this driver see the
1018 I8K Linux utilities web site at:
1019 <http://people.debian.org/~dz/i8k/>
1020
1021 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
1022 Say N otherwise.
1023
1024 config X86_REBOOTFIXUPS
1025 bool "Enable X86 board specific fixups for reboot"
1026 depends on X86_32
1027 ---help---
1028 This enables chipset and/or board specific fixups to be done
1029 in order to get reboot to work correctly. This is only needed on
1030 some combinations of hardware and BIOS. The symptom, for which
1031 this config is intended, is when reboot ends with a stalled/hung
1032 system.
1033
1034 Currently, the only fixup is for the Geode machines using
1035 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
1036
1037 Say Y if you want to enable the fixup. Currently, it's safe to
1038 enable this option even if you don't need it.
1039 Say N otherwise.
1040
1041 config MICROCODE
1042 tristate "CPU microcode loading support"
1043 depends on CPU_SUP_AMD || CPU_SUP_INTEL
1044 select FW_LOADER
1045 ---help---
1046
1047 If you say Y here, you will be able to update the microcode on
1048 certain Intel and AMD processors. The Intel support is for the
1049 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4,
1050 Xeon etc. The AMD support is for families 0x10 and later. You will
1051 obviously need the actual microcode binary data itself which is not
1052 shipped with the Linux kernel.
1053
1054 This option selects the general module only, you need to select
1055 at least one vendor specific module as well.
1056
1057 To compile this driver as a module, choose M here: the module
1058 will be called microcode.
1059
1060 config MICROCODE_INTEL
1061 bool "Intel microcode loading support"
1062 depends on MICROCODE
1063 default MICROCODE
1064 select FW_LOADER
1065 ---help---
1066 This options enables microcode patch loading support for Intel
1067 processors.
1068
1069 For the current Intel microcode data package go to
1070 <https://downloadcenter.intel.com> and search for
1071 'Linux Processor Microcode Data File'.
1072
1073 config MICROCODE_AMD
1074 bool "AMD microcode loading support"
1075 depends on MICROCODE
1076 select FW_LOADER
1077 ---help---
1078 If you select this option, microcode patch loading support for AMD
1079 processors will be enabled.
1080
1081 config MICROCODE_OLD_INTERFACE
1082 def_bool y
1083 depends on MICROCODE
1084
1085 config MICROCODE_INTEL_EARLY
1086 def_bool n
1087
1088 config MICROCODE_AMD_EARLY
1089 def_bool n
1090
1091 config MICROCODE_EARLY
1092 bool "Early load microcode"
1093 depends on MICROCODE=y && BLK_DEV_INITRD
1094 select MICROCODE_INTEL_EARLY if MICROCODE_INTEL
1095 select MICROCODE_AMD_EARLY if MICROCODE_AMD
1096 default y
1097 help
1098 This option provides functionality to read additional microcode data
1099 at the beginning of initrd image. The data tells kernel to load
1100 microcode to CPU's as early as possible. No functional change if no
1101 microcode data is glued to the initrd, therefore it's safe to say Y.
1102
1103 config X86_MSR
1104 tristate "/dev/cpu/*/msr - Model-specific register support"
1105 ---help---
1106 This device gives privileged processes access to the x86
1107 Model-Specific Registers (MSRs). It is a character device with
1108 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
1109 MSR accesses are directed to a specific CPU on multi-processor
1110 systems.
1111
1112 config X86_CPUID
1113 tristate "/dev/cpu/*/cpuid - CPU information support"
1114 ---help---
1115 This device gives processes access to the x86 CPUID instruction to
1116 be executed on a specific processor. It is a character device
1117 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
1118 /dev/cpu/31/cpuid.
1119
1120 choice
1121 prompt "High Memory Support"
1122 default HIGHMEM4G
1123 depends on X86_32
1124
1125 config NOHIGHMEM
1126 bool "off"
1127 ---help---
1128 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
1129 However, the address space of 32-bit x86 processors is only 4
1130 Gigabytes large. That means that, if you have a large amount of
1131 physical memory, not all of it can be "permanently mapped" by the
1132 kernel. The physical memory that's not permanently mapped is called
1133 "high memory".
1134
1135 If you are compiling a kernel which will never run on a machine with
1136 more than 1 Gigabyte total physical RAM, answer "off" here (default
1137 choice and suitable for most users). This will result in a "3GB/1GB"
1138 split: 3GB are mapped so that each process sees a 3GB virtual memory
1139 space and the remaining part of the 4GB virtual memory space is used
1140 by the kernel to permanently map as much physical memory as
1141 possible.
1142
1143 If the machine has between 1 and 4 Gigabytes physical RAM, then
1144 answer "4GB" here.
1145
1146 If more than 4 Gigabytes is used then answer "64GB" here. This
1147 selection turns Intel PAE (Physical Address Extension) mode on.
1148 PAE implements 3-level paging on IA32 processors. PAE is fully
1149 supported by Linux, PAE mode is implemented on all recent Intel
1150 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
1151 then the kernel will not boot on CPUs that don't support PAE!
1152
1153 The actual amount of total physical memory will either be
1154 auto detected or can be forced by using a kernel command line option
1155 such as "mem=256M". (Try "man bootparam" or see the documentation of
1156 your boot loader (lilo or loadlin) about how to pass options to the
1157 kernel at boot time.)
1158
1159 If unsure, say "off".
1160
1161 config HIGHMEM4G
1162 bool "4GB"
1163 ---help---
1164 Select this if you have a 32-bit processor and between 1 and 4
1165 gigabytes of physical RAM.
1166
1167 config HIGHMEM64G
1168 bool "64GB"
1169 depends on !M486
1170 select X86_PAE
1171 ---help---
1172 Select this if you have a 32-bit processor and more than 4
1173 gigabytes of physical RAM.
1174
1175 endchoice
1176
1177 choice
1178 prompt "Memory split" if EXPERT
1179 default VMSPLIT_3G
1180 depends on X86_32
1181 ---help---
1182 Select the desired split between kernel and user memory.
1183
1184 If the address range available to the kernel is less than the
1185 physical memory installed, the remaining memory will be available
1186 as "high memory". Accessing high memory is a little more costly
1187 than low memory, as it needs to be mapped into the kernel first.
1188 Note that increasing the kernel address space limits the range
1189 available to user programs, making the address space there
1190 tighter. Selecting anything other than the default 3G/1G split
1191 will also likely make your kernel incompatible with binary-only
1192 kernel modules.
1193
1194 If you are not absolutely sure what you are doing, leave this
1195 option alone!
1196
1197 config VMSPLIT_3G
1198 bool "3G/1G user/kernel split"
1199 config VMSPLIT_3G_OPT
1200 depends on !X86_PAE
1201 bool "3G/1G user/kernel split (for full 1G low memory)"
1202 config VMSPLIT_2G
1203 bool "2G/2G user/kernel split"
1204 config VMSPLIT_2G_OPT
1205 depends on !X86_PAE
1206 bool "2G/2G user/kernel split (for full 2G low memory)"
1207 config VMSPLIT_1G
1208 bool "1G/3G user/kernel split"
1209 endchoice
1210
1211 config PAGE_OFFSET
1212 hex
1213 default 0xB0000000 if VMSPLIT_3G_OPT
1214 default 0x80000000 if VMSPLIT_2G
1215 default 0x78000000 if VMSPLIT_2G_OPT
1216 default 0x40000000 if VMSPLIT_1G
1217 default 0xC0000000
1218 depends on X86_32
1219
1220 config HIGHMEM
1221 def_bool y
1222 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
1223
1224 config X86_PAE
1225 bool "PAE (Physical Address Extension) Support"
1226 depends on X86_32 && !HIGHMEM4G
1227 ---help---
1228 PAE is required for NX support, and furthermore enables
1229 larger swapspace support for non-overcommit purposes. It
1230 has the cost of more pagetable lookup overhead, and also
1231 consumes more pagetable space per process.
1232
1233 config ARCH_PHYS_ADDR_T_64BIT
1234 def_bool y
1235 depends on X86_64 || X86_PAE
1236
1237 config ARCH_DMA_ADDR_T_64BIT
1238 def_bool y
1239 depends on X86_64 || HIGHMEM64G
1240
1241 config DIRECT_GBPAGES
1242 bool "Enable 1GB pages for kernel pagetables" if EXPERT
1243 default y
1244 depends on X86_64
1245 ---help---
1246 Allow the kernel linear mapping to use 1GB pages on CPUs that
1247 support it. This can improve the kernel's performance a tiny bit by
1248 reducing TLB pressure. If in doubt, say "Y".
1249
1250 # Common NUMA Features
1251 config NUMA
1252 bool "Numa Memory Allocation and Scheduler Support"
1253 depends on SMP
1254 depends on X86_64 || (X86_32 && HIGHMEM64G && X86_BIGSMP)
1255 default y if X86_BIGSMP
1256 ---help---
1257 Enable NUMA (Non Uniform Memory Access) support.
1258
1259 The kernel will try to allocate memory used by a CPU on the
1260 local memory controller of the CPU and add some more
1261 NUMA awareness to the kernel.
1262
1263 For 64-bit this is recommended if the system is Intel Core i7
1264 (or later), AMD Opteron, or EM64T NUMA.
1265
1266 For 32-bit this is only needed if you boot a 32-bit
1267 kernel on a 64-bit NUMA platform.
1268
1269 Otherwise, you should say N.
1270
1271 config AMD_NUMA
1272 def_bool y
1273 prompt "Old style AMD Opteron NUMA detection"
1274 depends on X86_64 && NUMA && PCI
1275 ---help---
1276 Enable AMD NUMA node topology detection. You should say Y here if
1277 you have a multi processor AMD system. This uses an old method to
1278 read the NUMA configuration directly from the builtin Northbridge
1279 of Opteron. It is recommended to use X86_64_ACPI_NUMA instead,
1280 which also takes priority if both are compiled in.
1281
1282 config X86_64_ACPI_NUMA
1283 def_bool y
1284 prompt "ACPI NUMA detection"
1285 depends on X86_64 && NUMA && ACPI && PCI
1286 select ACPI_NUMA
1287 ---help---
1288 Enable ACPI SRAT based node topology detection.
1289
1290 # Some NUMA nodes have memory ranges that span
1291 # other nodes. Even though a pfn is valid and
1292 # between a node's start and end pfns, it may not
1293 # reside on that node. See memmap_init_zone()
1294 # for details.
1295 config NODES_SPAN_OTHER_NODES
1296 def_bool y
1297 depends on X86_64_ACPI_NUMA
1298
1299 config NUMA_EMU
1300 bool "NUMA emulation"
1301 depends on NUMA
1302 ---help---
1303 Enable NUMA emulation. A flat machine will be split
1304 into virtual nodes when booted with "numa=fake=N", where N is the
1305 number of nodes. This is only useful for debugging.
1306
1307 config NODES_SHIFT
1308 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1309 range 1 10
1310 default "10" if MAXSMP
1311 default "6" if X86_64
1312 default "3"
1313 depends on NEED_MULTIPLE_NODES
1314 ---help---
1315 Specify the maximum number of NUMA Nodes available on the target
1316 system. Increases memory reserved to accommodate various tables.
1317
1318 config ARCH_HAVE_MEMORY_PRESENT
1319 def_bool y
1320 depends on X86_32 && DISCONTIGMEM
1321
1322 config NEED_NODE_MEMMAP_SIZE
1323 def_bool y
1324 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1325
1326 config ARCH_FLATMEM_ENABLE
1327 def_bool y
1328 depends on X86_32 && !NUMA
1329
1330 config ARCH_DISCONTIGMEM_ENABLE
1331 def_bool y
1332 depends on NUMA && X86_32
1333
1334 config ARCH_DISCONTIGMEM_DEFAULT
1335 def_bool y
1336 depends on NUMA && X86_32
1337
1338 config ARCH_SPARSEMEM_ENABLE
1339 def_bool y
1340 depends on X86_64 || NUMA || X86_32 || X86_32_NON_STANDARD
1341 select SPARSEMEM_STATIC if X86_32
1342 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1343
1344 config ARCH_SPARSEMEM_DEFAULT
1345 def_bool y
1346 depends on X86_64
1347
1348 config ARCH_SELECT_MEMORY_MODEL
1349 def_bool y
1350 depends on ARCH_SPARSEMEM_ENABLE
1351
1352 config ARCH_MEMORY_PROBE
1353 bool "Enable sysfs memory/probe interface"
1354 depends on X86_64 && MEMORY_HOTPLUG
1355 help
1356 This option enables a sysfs memory/probe interface for testing.
1357 See Documentation/memory-hotplug.txt for more information.
1358 If you are unsure how to answer this question, answer N.
1359
1360 config ARCH_PROC_KCORE_TEXT
1361 def_bool y
1362 depends on X86_64 && PROC_KCORE
1363
1364 config ILLEGAL_POINTER_VALUE
1365 hex
1366 default 0 if X86_32
1367 default 0xdead000000000000 if X86_64
1368
1369 source "mm/Kconfig"
1370
1371 config HIGHPTE
1372 bool "Allocate 3rd-level pagetables from highmem"
1373 depends on HIGHMEM
1374 ---help---
1375 The VM uses one page table entry for each page of physical memory.
1376 For systems with a lot of RAM, this can be wasteful of precious
1377 low memory. Setting this option will put user-space page table
1378 entries in high memory.
1379
1380 config X86_CHECK_BIOS_CORRUPTION
1381 bool "Check for low memory corruption"
1382 ---help---
1383 Periodically check for memory corruption in low memory, which
1384 is suspected to be caused by BIOS. Even when enabled in the
1385 configuration, it is disabled at runtime. Enable it by
1386 setting "memory_corruption_check=1" on the kernel command
1387 line. By default it scans the low 64k of memory every 60
1388 seconds; see the memory_corruption_check_size and
1389 memory_corruption_check_period parameters in
1390 Documentation/kernel-parameters.txt to adjust this.
1391
1392 When enabled with the default parameters, this option has
1393 almost no overhead, as it reserves a relatively small amount
1394 of memory and scans it infrequently. It both detects corruption
1395 and prevents it from affecting the running system.
1396
1397 It is, however, intended as a diagnostic tool; if repeatable
1398 BIOS-originated corruption always affects the same memory,
1399 you can use memmap= to prevent the kernel from using that
1400 memory.
1401
1402 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1403 bool "Set the default setting of memory_corruption_check"
1404 depends on X86_CHECK_BIOS_CORRUPTION
1405 default y
1406 ---help---
1407 Set whether the default state of memory_corruption_check is
1408 on or off.
1409
1410 config X86_RESERVE_LOW
1411 int "Amount of low memory, in kilobytes, to reserve for the BIOS"
1412 default 64
1413 range 4 640
1414 ---help---
1415 Specify the amount of low memory to reserve for the BIOS.
1416
1417 The first page contains BIOS data structures that the kernel
1418 must not use, so that page must always be reserved.
1419
1420 By default we reserve the first 64K of physical RAM, as a
1421 number of BIOSes are known to corrupt that memory range
1422 during events such as suspend/resume or monitor cable
1423 insertion, so it must not be used by the kernel.
1424
1425 You can set this to 4 if you are absolutely sure that you
1426 trust the BIOS to get all its memory reservations and usages
1427 right. If you know your BIOS have problems beyond the
1428 default 64K area, you can set this to 640 to avoid using the
1429 entire low memory range.
1430
1431 If you have doubts about the BIOS (e.g. suspend/resume does
1432 not work or there's kernel crashes after certain hardware
1433 hotplug events) then you might want to enable
1434 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check
1435 typical corruption patterns.
1436
1437 Leave this to the default value of 64 if you are unsure.
1438
1439 config MATH_EMULATION
1440 bool
1441 prompt "Math emulation" if X86_32
1442 ---help---
1443 Linux can emulate a math coprocessor (used for floating point
1444 operations) if you don't have one. 486DX and Pentium processors have
1445 a math coprocessor built in, 486SX and 386 do not, unless you added
1446 a 487DX or 387, respectively. (The messages during boot time can
1447 give you some hints here ["man dmesg"].) Everyone needs either a
1448 coprocessor or this emulation.
1449
1450 If you don't have a math coprocessor, you need to say Y here; if you
1451 say Y here even though you have a coprocessor, the coprocessor will
1452 be used nevertheless. (This behavior can be changed with the kernel
1453 command line option "no387", which comes handy if your coprocessor
1454 is broken. Try "man bootparam" or see the documentation of your boot
1455 loader (lilo or loadlin) about how to pass options to the kernel at
1456 boot time.) This means that it is a good idea to say Y here if you
1457 intend to use this kernel on different machines.
1458
1459 More information about the internals of the Linux math coprocessor
1460 emulation can be found in <file:arch/x86/math-emu/README>.
1461
1462 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1463 kernel, it won't hurt.
1464
1465 config MTRR
1466 def_bool y
1467 prompt "MTRR (Memory Type Range Register) support" if EXPERT
1468 ---help---
1469 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1470 the Memory Type Range Registers (MTRRs) may be used to control
1471 processor access to memory ranges. This is most useful if you have
1472 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1473 allows bus write transfers to be combined into a larger transfer
1474 before bursting over the PCI/AGP bus. This can increase performance
1475 of image write operations 2.5 times or more. Saying Y here creates a
1476 /proc/mtrr file which may be used to manipulate your processor's
1477 MTRRs. Typically the X server should use this.
1478
1479 This code has a reasonably generic interface so that similar
1480 control registers on other processors can be easily supported
1481 as well:
1482
1483 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1484 Registers (ARRs) which provide a similar functionality to MTRRs. For
1485 these, the ARRs are used to emulate the MTRRs.
1486 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1487 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1488 write-combining. All of these processors are supported by this code
1489 and it makes sense to say Y here if you have one of them.
1490
1491 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1492 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1493 can lead to all sorts of problems, so it's good to say Y here.
1494
1495 You can safely say Y even if your machine doesn't have MTRRs, you'll
1496 just add about 9 KB to your kernel.
1497
1498 See <file:Documentation/x86/mtrr.txt> for more information.
1499
1500 config MTRR_SANITIZER
1501 def_bool y
1502 prompt "MTRR cleanup support"
1503 depends on MTRR
1504 ---help---
1505 Convert MTRR layout from continuous to discrete, so X drivers can
1506 add writeback entries.
1507
1508 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1509 The largest mtrr entry size for a continuous block can be set with
1510 mtrr_chunk_size.
1511
1512 If unsure, say Y.
1513
1514 config MTRR_SANITIZER_ENABLE_DEFAULT
1515 int "MTRR cleanup enable value (0-1)"
1516 range 0 1
1517 default "0"
1518 depends on MTRR_SANITIZER
1519 ---help---
1520 Enable mtrr cleanup default value
1521
1522 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1523 int "MTRR cleanup spare reg num (0-7)"
1524 range 0 7
1525 default "1"
1526 depends on MTRR_SANITIZER
1527 ---help---
1528 mtrr cleanup spare entries default, it can be changed via
1529 mtrr_spare_reg_nr=N on the kernel command line.
1530
1531 config X86_PAT
1532 def_bool y
1533 prompt "x86 PAT support" if EXPERT
1534 depends on MTRR
1535 ---help---
1536 Use PAT attributes to setup page level cache control.
1537
1538 PATs are the modern equivalents of MTRRs and are much more
1539 flexible than MTRRs.
1540
1541 Say N here if you see bootup problems (boot crash, boot hang,
1542 spontaneous reboots) or a non-working video driver.
1543
1544 If unsure, say Y.
1545
1546 config ARCH_USES_PG_UNCACHED
1547 def_bool y
1548 depends on X86_PAT
1549
1550 config ARCH_RANDOM
1551 def_bool y
1552 prompt "x86 architectural random number generator" if EXPERT
1553 ---help---
1554 Enable the x86 architectural RDRAND instruction
1555 (Intel Bull Mountain technology) to generate random numbers.
1556 If supported, this is a high bandwidth, cryptographically
1557 secure hardware random number generator.
1558
1559 config X86_SMAP
1560 def_bool y
1561 prompt "Supervisor Mode Access Prevention" if EXPERT
1562 ---help---
1563 Supervisor Mode Access Prevention (SMAP) is a security
1564 feature in newer Intel processors. There is a small
1565 performance cost if this enabled and turned on; there is
1566 also a small increase in the kernel size if this is enabled.
1567
1568 If unsure, say Y.
1569
1570 config EFI
1571 bool "EFI runtime service support"
1572 depends on ACPI
1573 select UCS2_STRING
1574 select EFI_RUNTIME_WRAPPERS
1575 ---help---
1576 This enables the kernel to use EFI runtime services that are
1577 available (such as the EFI variable services).
1578
1579 This option is only useful on systems that have EFI firmware.
1580 In addition, you should use the latest ELILO loader available
1581 at <http://elilo.sourceforge.net> in order to take advantage
1582 of EFI runtime services. However, even with this option, the
1583 resultant kernel should continue to boot on existing non-EFI
1584 platforms.
1585
1586 config EFI_STUB
1587 bool "EFI stub support"
1588 depends on EFI && !X86_USE_3DNOW
1589 select RELOCATABLE
1590 ---help---
1591 This kernel feature allows a bzImage to be loaded directly
1592 by EFI firmware without the use of a bootloader.
1593
1594 See Documentation/efi-stub.txt for more information.
1595
1596 config EFI_MIXED
1597 bool "EFI mixed-mode support"
1598 depends on EFI_STUB && X86_64
1599 ---help---
1600 Enabling this feature allows a 64-bit kernel to be booted
1601 on a 32-bit firmware, provided that your CPU supports 64-bit
1602 mode.
1603
1604 Note that it is not possible to boot a mixed-mode enabled
1605 kernel via the EFI boot stub - a bootloader that supports
1606 the EFI handover protocol must be used.
1607
1608 If unsure, say N.
1609
1610 config SECCOMP
1611 def_bool y
1612 prompt "Enable seccomp to safely compute untrusted bytecode"
1613 ---help---
1614 This kernel feature is useful for number crunching applications
1615 that may need to compute untrusted bytecode during their
1616 execution. By using pipes or other transports made available to
1617 the process as file descriptors supporting the read/write
1618 syscalls, it's possible to isolate those applications in
1619 their own address space using seccomp. Once seccomp is
1620 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1621 and the task is only allowed to execute a few safe syscalls
1622 defined by each seccomp mode.
1623
1624 If unsure, say Y. Only embedded should say N here.
1625
1626 source kernel/Kconfig.hz
1627
1628 config KEXEC
1629 bool "kexec system call"
1630 ---help---
1631 kexec is a system call that implements the ability to shutdown your
1632 current kernel, and to start another kernel. It is like a reboot
1633 but it is independent of the system firmware. And like a reboot
1634 you can start any kernel with it, not just Linux.
1635
1636 The name comes from the similarity to the exec system call.
1637
1638 It is an ongoing process to be certain the hardware in a machine
1639 is properly shutdown, so do not be surprised if this code does not
1640 initially work for you. As of this writing the exact hardware
1641 interface is strongly in flux, so no good recommendation can be
1642 made.
1643
1644 config KEXEC_FILE
1645 bool "kexec file based system call"
1646 select BUILD_BIN2C
1647 depends on KEXEC
1648 depends on X86_64
1649 depends on CRYPTO=y
1650 depends on CRYPTO_SHA256=y
1651 ---help---
1652 This is new version of kexec system call. This system call is
1653 file based and takes file descriptors as system call argument
1654 for kernel and initramfs as opposed to list of segments as
1655 accepted by previous system call.
1656
1657 config KEXEC_VERIFY_SIG
1658 bool "Verify kernel signature during kexec_file_load() syscall"
1659 depends on KEXEC_FILE
1660 ---help---
1661 This option makes kernel signature verification mandatory for
1662 kexec_file_load() syscall. If kernel is signature can not be
1663 verified, kexec_file_load() will fail.
1664
1665 This option enforces signature verification at generic level.
1666 One needs to enable signature verification for type of kernel
1667 image being loaded to make sure it works. For example, enable
1668 bzImage signature verification option to be able to load and
1669 verify signatures of bzImage. Otherwise kernel loading will fail.
1670
1671 config KEXEC_BZIMAGE_VERIFY_SIG
1672 bool "Enable bzImage signature verification support"
1673 depends on KEXEC_VERIFY_SIG
1674 depends on SIGNED_PE_FILE_VERIFICATION
1675 select SYSTEM_TRUSTED_KEYRING
1676 ---help---
1677 Enable bzImage signature verification support.
1678
1679 config CRASH_DUMP
1680 bool "kernel crash dumps"
1681 depends on X86_64 || (X86_32 && HIGHMEM)
1682 ---help---
1683 Generate crash dump after being started by kexec.
1684 This should be normally only set in special crash dump kernels
1685 which are loaded in the main kernel with kexec-tools into
1686 a specially reserved region and then later executed after
1687 a crash by kdump/kexec. The crash dump kernel must be compiled
1688 to a memory address not used by the main kernel or BIOS using
1689 PHYSICAL_START, or it must be built as a relocatable image
1690 (CONFIG_RELOCATABLE=y).
1691 For more details see Documentation/kdump/kdump.txt
1692
1693 config KEXEC_JUMP
1694 bool "kexec jump"
1695 depends on KEXEC && HIBERNATION
1696 ---help---
1697 Jump between original kernel and kexeced kernel and invoke
1698 code in physical address mode via KEXEC
1699
1700 config PHYSICAL_START
1701 hex "Physical address where the kernel is loaded" if (EXPERT || CRASH_DUMP)
1702 default "0x1000000"
1703 ---help---
1704 This gives the physical address where the kernel is loaded.
1705
1706 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1707 bzImage will decompress itself to above physical address and
1708 run from there. Otherwise, bzImage will run from the address where
1709 it has been loaded by the boot loader and will ignore above physical
1710 address.
1711
1712 In normal kdump cases one does not have to set/change this option
1713 as now bzImage can be compiled as a completely relocatable image
1714 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1715 address. This option is mainly useful for the folks who don't want
1716 to use a bzImage for capturing the crash dump and want to use a
1717 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1718 to be specifically compiled to run from a specific memory area
1719 (normally a reserved region) and this option comes handy.
1720
1721 So if you are using bzImage for capturing the crash dump,
1722 leave the value here unchanged to 0x1000000 and set
1723 CONFIG_RELOCATABLE=y. Otherwise if you plan to use vmlinux
1724 for capturing the crash dump change this value to start of
1725 the reserved region. In other words, it can be set based on
1726 the "X" value as specified in the "crashkernel=YM@XM"
1727 command line boot parameter passed to the panic-ed
1728 kernel. Please take a look at Documentation/kdump/kdump.txt
1729 for more details about crash dumps.
1730
1731 Usage of bzImage for capturing the crash dump is recommended as
1732 one does not have to build two kernels. Same kernel can be used
1733 as production kernel and capture kernel. Above option should have
1734 gone away after relocatable bzImage support is introduced. But it
1735 is present because there are users out there who continue to use
1736 vmlinux for dump capture. This option should go away down the
1737 line.
1738
1739 Don't change this unless you know what you are doing.
1740
1741 config RELOCATABLE
1742 bool "Build a relocatable kernel"
1743 default y
1744 ---help---
1745 This builds a kernel image that retains relocation information
1746 so it can be loaded someplace besides the default 1MB.
1747 The relocations tend to make the kernel binary about 10% larger,
1748 but are discarded at runtime.
1749
1750 One use is for the kexec on panic case where the recovery kernel
1751 must live at a different physical address than the primary
1752 kernel.
1753
1754 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1755 it has been loaded at and the compile time physical address
1756 (CONFIG_PHYSICAL_START) is used as the minimum location.
1757
1758 config RANDOMIZE_BASE
1759 bool "Randomize the address of the kernel image"
1760 depends on RELOCATABLE
1761 default n
1762 ---help---
1763 Randomizes the physical and virtual address at which the
1764 kernel image is decompressed, as a security feature that
1765 deters exploit attempts relying on knowledge of the location
1766 of kernel internals.
1767
1768 Entropy is generated using the RDRAND instruction if it is
1769 supported. If RDTSC is supported, it is used as well. If
1770 neither RDRAND nor RDTSC are supported, then randomness is
1771 read from the i8254 timer.
1772
1773 The kernel will be offset by up to RANDOMIZE_BASE_MAX_OFFSET,
1774 and aligned according to PHYSICAL_ALIGN. Since the kernel is
1775 built using 2GiB addressing, and PHYSICAL_ALGIN must be at a
1776 minimum of 2MiB, only 10 bits of entropy is theoretically
1777 possible. At best, due to page table layouts, 64-bit can use
1778 9 bits of entropy and 32-bit uses 8 bits.
1779
1780 If unsure, say N.
1781
1782 config RANDOMIZE_BASE_MAX_OFFSET
1783 hex "Maximum kASLR offset allowed" if EXPERT
1784 depends on RANDOMIZE_BASE
1785 range 0x0 0x20000000 if X86_32
1786 default "0x20000000" if X86_32
1787 range 0x0 0x40000000 if X86_64
1788 default "0x40000000" if X86_64
1789 ---help---
1790 The lesser of RANDOMIZE_BASE_MAX_OFFSET and available physical
1791 memory is used to determine the maximal offset in bytes that will
1792 be applied to the kernel when kernel Address Space Layout
1793 Randomization (kASLR) is active. This must be a multiple of
1794 PHYSICAL_ALIGN.
1795
1796 On 32-bit this is limited to 512MiB by page table layouts. The
1797 default is 512MiB.
1798
1799 On 64-bit this is limited by how the kernel fixmap page table is
1800 positioned, so this cannot be larger than 1GiB currently. Without
1801 RANDOMIZE_BASE, there is a 512MiB to 1.5GiB split between kernel
1802 and modules. When RANDOMIZE_BASE_MAX_OFFSET is above 512MiB, the
1803 modules area will shrink to compensate, up to the current maximum
1804 1GiB to 1GiB split. The default is 1GiB.
1805
1806 If unsure, leave at the default value.
1807
1808 # Relocation on x86 needs some additional build support
1809 config X86_NEED_RELOCS
1810 def_bool y
1811 depends on RANDOMIZE_BASE || (X86_32 && RELOCATABLE)
1812
1813 config PHYSICAL_ALIGN
1814 hex "Alignment value to which kernel should be aligned"
1815 default "0x200000"
1816 range 0x2000 0x1000000 if X86_32
1817 range 0x200000 0x1000000 if X86_64
1818 ---help---
1819 This value puts the alignment restrictions on physical address
1820 where kernel is loaded and run from. Kernel is compiled for an
1821 address which meets above alignment restriction.
1822
1823 If bootloader loads the kernel at a non-aligned address and
1824 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1825 address aligned to above value and run from there.
1826
1827 If bootloader loads the kernel at a non-aligned address and
1828 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1829 load address and decompress itself to the address it has been
1830 compiled for and run from there. The address for which kernel is
1831 compiled already meets above alignment restrictions. Hence the
1832 end result is that kernel runs from a physical address meeting
1833 above alignment restrictions.
1834
1835 On 32-bit this value must be a multiple of 0x2000. On 64-bit
1836 this value must be a multiple of 0x200000.
1837
1838 Don't change this unless you know what you are doing.
1839
1840 config HOTPLUG_CPU
1841 bool "Support for hot-pluggable CPUs"
1842 depends on SMP
1843 ---help---
1844 Say Y here to allow turning CPUs off and on. CPUs can be
1845 controlled through /sys/devices/system/cpu.
1846 ( Note: power management support will enable this option
1847 automatically on SMP systems. )
1848 Say N if you want to disable CPU hotplug.
1849
1850 config BOOTPARAM_HOTPLUG_CPU0
1851 bool "Set default setting of cpu0_hotpluggable"
1852 default n
1853 depends on HOTPLUG_CPU
1854 ---help---
1855 Set whether default state of cpu0_hotpluggable is on or off.
1856
1857 Say Y here to enable CPU0 hotplug by default. If this switch
1858 is turned on, there is no need to give cpu0_hotplug kernel
1859 parameter and the CPU0 hotplug feature is enabled by default.
1860
1861 Please note: there are two known CPU0 dependencies if you want
1862 to enable the CPU0 hotplug feature either by this switch or by
1863 cpu0_hotplug kernel parameter.
1864
1865 First, resume from hibernate or suspend always starts from CPU0.
1866 So hibernate and suspend are prevented if CPU0 is offline.
1867
1868 Second dependency is PIC interrupts always go to CPU0. CPU0 can not
1869 offline if any interrupt can not migrate out of CPU0. There may
1870 be other CPU0 dependencies.
1871
1872 Please make sure the dependencies are under your control before
1873 you enable this feature.
1874
1875 Say N if you don't want to enable CPU0 hotplug feature by default.
1876 You still can enable the CPU0 hotplug feature at boot by kernel
1877 parameter cpu0_hotplug.
1878
1879 config DEBUG_HOTPLUG_CPU0
1880 def_bool n
1881 prompt "Debug CPU0 hotplug"
1882 depends on HOTPLUG_CPU
1883 ---help---
1884 Enabling this option offlines CPU0 (if CPU0 can be offlined) as
1885 soon as possible and boots up userspace with CPU0 offlined. User
1886 can online CPU0 back after boot time.
1887
1888 To debug CPU0 hotplug, you need to enable CPU0 offline/online
1889 feature by either turning on CONFIG_BOOTPARAM_HOTPLUG_CPU0 during
1890 compilation or giving cpu0_hotplug kernel parameter at boot.
1891
1892 If unsure, say N.
1893
1894 config COMPAT_VDSO
1895 def_bool n
1896 prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
1897 depends on X86_32 || IA32_EMULATION
1898 ---help---
1899 Certain buggy versions of glibc will crash if they are
1900 presented with a 32-bit vDSO that is not mapped at the address
1901 indicated in its segment table.
1902
1903 The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a
1904 and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and
1905 49ad572a70b8aeb91e57483a11dd1b77e31c4468. Glibc 2.3.3 is
1906 the only released version with the bug, but OpenSUSE 9
1907 contains a buggy "glibc 2.3.2".
1908
1909 The symptom of the bug is that everything crashes on startup, saying:
1910 dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!
1911
1912 Saying Y here changes the default value of the vdso32 boot
1913 option from 1 to 0, which turns off the 32-bit vDSO entirely.
1914 This works around the glibc bug but hurts performance.
1915
1916 If unsure, say N: if you are compiling your own kernel, you
1917 are unlikely to be using a buggy version of glibc.
1918
1919 config CMDLINE_BOOL
1920 bool "Built-in kernel command line"
1921 ---help---
1922 Allow for specifying boot arguments to the kernel at
1923 build time. On some systems (e.g. embedded ones), it is
1924 necessary or convenient to provide some or all of the
1925 kernel boot arguments with the kernel itself (that is,
1926 to not rely on the boot loader to provide them.)
1927
1928 To compile command line arguments into the kernel,
1929 set this option to 'Y', then fill in the
1930 the boot arguments in CONFIG_CMDLINE.
1931
1932 Systems with fully functional boot loaders (i.e. non-embedded)
1933 should leave this option set to 'N'.
1934
1935 config CMDLINE
1936 string "Built-in kernel command string"
1937 depends on CMDLINE_BOOL
1938 default ""
1939 ---help---
1940 Enter arguments here that should be compiled into the kernel
1941 image and used at boot time. If the boot loader provides a
1942 command line at boot time, it is appended to this string to
1943 form the full kernel command line, when the system boots.
1944
1945 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1946 change this behavior.
1947
1948 In most cases, the command line (whether built-in or provided
1949 by the boot loader) should specify the device for the root
1950 file system.
1951
1952 config CMDLINE_OVERRIDE
1953 bool "Built-in command line overrides boot loader arguments"
1954 depends on CMDLINE_BOOL
1955 ---help---
1956 Set this option to 'Y' to have the kernel ignore the boot loader
1957 command line, and use ONLY the built-in command line.
1958
1959 This is used to work around broken boot loaders. This should
1960 be set to 'N' under normal conditions.
1961
1962 endmenu
1963
1964 config ARCH_ENABLE_MEMORY_HOTPLUG
1965 def_bool y
1966 depends on X86_64 || (X86_32 && HIGHMEM)
1967
1968 config ARCH_ENABLE_MEMORY_HOTREMOVE
1969 def_bool y
1970 depends on MEMORY_HOTPLUG
1971
1972 config USE_PERCPU_NUMA_NODE_ID
1973 def_bool y
1974 depends on NUMA
1975
1976 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
1977 def_bool y
1978 depends on X86_64 || X86_PAE
1979
1980 config ARCH_ENABLE_HUGEPAGE_MIGRATION
1981 def_bool y
1982 depends on X86_64 && HUGETLB_PAGE && MIGRATION
1983
1984 menu "Power management and ACPI options"
1985
1986 config ARCH_HIBERNATION_HEADER
1987 def_bool y
1988 depends on X86_64 && HIBERNATION
1989
1990 source "kernel/power/Kconfig"
1991
1992 source "drivers/acpi/Kconfig"
1993
1994 source "drivers/sfi/Kconfig"
1995
1996 config X86_APM_BOOT
1997 def_bool y
1998 depends on APM
1999
2000 menuconfig APM
2001 tristate "APM (Advanced Power Management) BIOS support"
2002 depends on X86_32 && PM_SLEEP
2003 ---help---
2004 APM is a BIOS specification for saving power using several different
2005 techniques. This is mostly useful for battery powered laptops with
2006 APM compliant BIOSes. If you say Y here, the system time will be
2007 reset after a RESUME operation, the /proc/apm device will provide
2008 battery status information, and user-space programs will receive
2009 notification of APM "events" (e.g. battery status change).
2010
2011 If you select "Y" here, you can disable actual use of the APM
2012 BIOS by passing the "apm=off" option to the kernel at boot time.
2013
2014 Note that the APM support is almost completely disabled for
2015 machines with more than one CPU.
2016
2017 In order to use APM, you will need supporting software. For location
2018 and more information, read <file:Documentation/power/apm-acpi.txt>
2019 and the Battery Powered Linux mini-HOWTO, available from
2020 <http://www.tldp.org/docs.html#howto>.
2021
2022 This driver does not spin down disk drives (see the hdparm(8)
2023 manpage ("man 8 hdparm") for that), and it doesn't turn off
2024 VESA-compliant "green" monitors.
2025
2026 This driver does not support the TI 4000M TravelMate and the ACER
2027 486/DX4/75 because they don't have compliant BIOSes. Many "green"
2028 desktop machines also don't have compliant BIOSes, and this driver
2029 may cause those machines to panic during the boot phase.
2030
2031 Generally, if you don't have a battery in your machine, there isn't
2032 much point in using this driver and you should say N. If you get
2033 random kernel OOPSes or reboots that don't seem to be related to
2034 anything, try disabling/enabling this option (or disabling/enabling
2035 APM in your BIOS).
2036
2037 Some other things you should try when experiencing seemingly random,
2038 "weird" problems:
2039
2040 1) make sure that you have enough swap space and that it is
2041 enabled.
2042 2) pass the "no-hlt" option to the kernel
2043 3) switch on floating point emulation in the kernel and pass
2044 the "no387" option to the kernel
2045 4) pass the "floppy=nodma" option to the kernel
2046 5) pass the "mem=4M" option to the kernel (thereby disabling
2047 all but the first 4 MB of RAM)
2048 6) make sure that the CPU is not over clocked.
2049 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
2050 8) disable the cache from your BIOS settings
2051 9) install a fan for the video card or exchange video RAM
2052 10) install a better fan for the CPU
2053 11) exchange RAM chips
2054 12) exchange the motherboard.
2055
2056 To compile this driver as a module, choose M here: the
2057 module will be called apm.
2058
2059 if APM
2060
2061 config APM_IGNORE_USER_SUSPEND
2062 bool "Ignore USER SUSPEND"
2063 ---help---
2064 This option will ignore USER SUSPEND requests. On machines with a
2065 compliant APM BIOS, you want to say N. However, on the NEC Versa M
2066 series notebooks, it is necessary to say Y because of a BIOS bug.
2067
2068 config APM_DO_ENABLE
2069 bool "Enable PM at boot time"
2070 ---help---
2071 Enable APM features at boot time. From page 36 of the APM BIOS
2072 specification: "When disabled, the APM BIOS does not automatically
2073 power manage devices, enter the Standby State, enter the Suspend
2074 State, or take power saving steps in response to CPU Idle calls."
2075 This driver will make CPU Idle calls when Linux is idle (unless this
2076 feature is turned off -- see "Do CPU IDLE calls", below). This
2077 should always save battery power, but more complicated APM features
2078 will be dependent on your BIOS implementation. You may need to turn
2079 this option off if your computer hangs at boot time when using APM
2080 support, or if it beeps continuously instead of suspending. Turn
2081 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
2082 T400CDT. This is off by default since most machines do fine without
2083 this feature.
2084
2085 config APM_CPU_IDLE
2086 depends on CPU_IDLE
2087 bool "Make CPU Idle calls when idle"
2088 ---help---
2089 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
2090 On some machines, this can activate improved power savings, such as
2091 a slowed CPU clock rate, when the machine is idle. These idle calls
2092 are made after the idle loop has run for some length of time (e.g.,
2093 333 mS). On some machines, this will cause a hang at boot time or
2094 whenever the CPU becomes idle. (On machines with more than one CPU,
2095 this option does nothing.)
2096
2097 config APM_DISPLAY_BLANK
2098 bool "Enable console blanking using APM"
2099 ---help---
2100 Enable console blanking using the APM. Some laptops can use this to
2101 turn off the LCD backlight when the screen blanker of the Linux
2102 virtual console blanks the screen. Note that this is only used by
2103 the virtual console screen blanker, and won't turn off the backlight
2104 when using the X Window system. This also doesn't have anything to
2105 do with your VESA-compliant power-saving monitor. Further, this
2106 option doesn't work for all laptops -- it might not turn off your
2107 backlight at all, or it might print a lot of errors to the console,
2108 especially if you are using gpm.
2109
2110 config APM_ALLOW_INTS
2111 bool "Allow interrupts during APM BIOS calls"
2112 ---help---
2113 Normally we disable external interrupts while we are making calls to
2114 the APM BIOS as a measure to lessen the effects of a badly behaving
2115 BIOS implementation. The BIOS should reenable interrupts if it
2116 needs to. Unfortunately, some BIOSes do not -- especially those in
2117 many of the newer IBM Thinkpads. If you experience hangs when you
2118 suspend, try setting this to Y. Otherwise, say N.
2119
2120 endif # APM
2121
2122 source "drivers/cpufreq/Kconfig"
2123
2124 source "drivers/cpuidle/Kconfig"
2125
2126 source "drivers/idle/Kconfig"
2127
2128 endmenu
2129
2130
2131 menu "Bus options (PCI etc.)"
2132
2133 config PCI
2134 bool "PCI support"
2135 default y
2136 ---help---
2137 Find out whether you have a PCI motherboard. PCI is the name of a
2138 bus system, i.e. the way the CPU talks to the other stuff inside
2139 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
2140 VESA. If you have PCI, say Y, otherwise N.
2141
2142 choice
2143 prompt "PCI access mode"
2144 depends on X86_32 && PCI
2145 default PCI_GOANY
2146 ---help---
2147 On PCI systems, the BIOS can be used to detect the PCI devices and
2148 determine their configuration. However, some old PCI motherboards
2149 have BIOS bugs and may crash if this is done. Also, some embedded
2150 PCI-based systems don't have any BIOS at all. Linux can also try to
2151 detect the PCI hardware directly without using the BIOS.
2152
2153 With this option, you can specify how Linux should detect the
2154 PCI devices. If you choose "BIOS", the BIOS will be used,
2155 if you choose "Direct", the BIOS won't be used, and if you
2156 choose "MMConfig", then PCI Express MMCONFIG will be used.
2157 If you choose "Any", the kernel will try MMCONFIG, then the
2158 direct access method and falls back to the BIOS if that doesn't
2159 work. If unsure, go with the default, which is "Any".
2160
2161 config PCI_GOBIOS
2162 bool "BIOS"
2163
2164 config PCI_GOMMCONFIG
2165 bool "MMConfig"
2166
2167 config PCI_GODIRECT
2168 bool "Direct"
2169
2170 config PCI_GOOLPC
2171 bool "OLPC XO-1"
2172 depends on OLPC
2173
2174 config PCI_GOANY
2175 bool "Any"
2176
2177 endchoice
2178
2179 config PCI_BIOS
2180 def_bool y
2181 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
2182
2183 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
2184 config PCI_DIRECT
2185 def_bool y
2186 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC || PCI_GOMMCONFIG))
2187
2188 config PCI_MMCONFIG
2189 def_bool y
2190 depends on X86_32 && PCI && (ACPI || SFI) && (PCI_GOMMCONFIG || PCI_GOANY)
2191
2192 config PCI_OLPC
2193 def_bool y
2194 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
2195
2196 config PCI_XEN
2197 def_bool y
2198 depends on PCI && XEN
2199 select SWIOTLB_XEN
2200
2201 config PCI_DOMAINS
2202 def_bool y
2203 depends on PCI
2204
2205 config PCI_MMCONFIG
2206 bool "Support mmconfig PCI config space access"
2207 depends on X86_64 && PCI && ACPI
2208
2209 config PCI_CNB20LE_QUIRK
2210 bool "Read CNB20LE Host Bridge Windows" if EXPERT
2211 depends on PCI
2212 help
2213 Read the PCI windows out of the CNB20LE host bridge. This allows
2214 PCI hotplug to work on systems with the CNB20LE chipset which do
2215 not have ACPI.
2216
2217 There's no public spec for this chipset, and this functionality
2218 is known to be incomplete.
2219
2220 You should say N unless you know you need this.
2221
2222 source "drivers/pci/pcie/Kconfig"
2223
2224 source "drivers/pci/Kconfig"
2225
2226 # x86_64 have no ISA slots, but can have ISA-style DMA.
2227 config ISA_DMA_API
2228 bool "ISA-style DMA support" if (X86_64 && EXPERT)
2229 default y
2230 help
2231 Enables ISA-style DMA support for devices requiring such controllers.
2232 If unsure, say Y.
2233
2234 if X86_32
2235
2236 config ISA
2237 bool "ISA support"
2238 ---help---
2239 Find out whether you have ISA slots on your motherboard. ISA is the
2240 name of a bus system, i.e. the way the CPU talks to the other stuff
2241 inside your box. Other bus systems are PCI, EISA, MicroChannel
2242 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
2243 newer boards don't support it. If you have ISA, say Y, otherwise N.
2244
2245 config EISA
2246 bool "EISA support"
2247 depends on ISA
2248 ---help---
2249 The Extended Industry Standard Architecture (EISA) bus was
2250 developed as an open alternative to the IBM MicroChannel bus.
2251
2252 The EISA bus provided some of the features of the IBM MicroChannel
2253 bus while maintaining backward compatibility with cards made for
2254 the older ISA bus. The EISA bus saw limited use between 1988 and
2255 1995 when it was made obsolete by the PCI bus.
2256
2257 Say Y here if you are building a kernel for an EISA-based machine.
2258
2259 Otherwise, say N.
2260
2261 source "drivers/eisa/Kconfig"
2262
2263 config SCx200
2264 tristate "NatSemi SCx200 support"
2265 ---help---
2266 This provides basic support for National Semiconductor's
2267 (now AMD's) Geode processors. The driver probes for the
2268 PCI-IDs of several on-chip devices, so its a good dependency
2269 for other scx200_* drivers.
2270
2271 If compiled as a module, the driver is named scx200.
2272
2273 config SCx200HR_TIMER
2274 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
2275 depends on SCx200
2276 default y
2277 ---help---
2278 This driver provides a clocksource built upon the on-chip
2279 27MHz high-resolution timer. Its also a workaround for
2280 NSC Geode SC-1100's buggy TSC, which loses time when the
2281 processor goes idle (as is done by the scheduler). The
2282 other workaround is idle=poll boot option.
2283
2284 config OLPC
2285 bool "One Laptop Per Child support"
2286 depends on !X86_PAE
2287 select GPIOLIB
2288 select OF
2289 select OF_PROMTREE
2290 select IRQ_DOMAIN
2291 ---help---
2292 Add support for detecting the unique features of the OLPC
2293 XO hardware.
2294
2295 config OLPC_XO1_PM
2296 bool "OLPC XO-1 Power Management"
2297 depends on OLPC && MFD_CS5535 && PM_SLEEP
2298 select MFD_CORE
2299 ---help---
2300 Add support for poweroff and suspend of the OLPC XO-1 laptop.
2301
2302 config OLPC_XO1_RTC
2303 bool "OLPC XO-1 Real Time Clock"
2304 depends on OLPC_XO1_PM && RTC_DRV_CMOS
2305 ---help---
2306 Add support for the XO-1 real time clock, which can be used as a
2307 programmable wakeup source.
2308
2309 config OLPC_XO1_SCI
2310 bool "OLPC XO-1 SCI extras"
2311 depends on OLPC && OLPC_XO1_PM
2312 depends on INPUT=y
2313 select POWER_SUPPLY
2314 select GPIO_CS5535
2315 select MFD_CORE
2316 ---help---
2317 Add support for SCI-based features of the OLPC XO-1 laptop:
2318 - EC-driven system wakeups
2319 - Power button
2320 - Ebook switch
2321 - Lid switch
2322 - AC adapter status updates
2323 - Battery status updates
2324
2325 config OLPC_XO15_SCI
2326 bool "OLPC XO-1.5 SCI extras"
2327 depends on OLPC && ACPI
2328 select POWER_SUPPLY
2329 ---help---
2330 Add support for SCI-based features of the OLPC XO-1.5 laptop:
2331 - EC-driven system wakeups
2332 - AC adapter status updates
2333 - Battery status updates
2334
2335 config ALIX
2336 bool "PCEngines ALIX System Support (LED setup)"
2337 select GPIOLIB
2338 ---help---
2339 This option enables system support for the PCEngines ALIX.
2340 At present this just sets up LEDs for GPIO control on
2341 ALIX2/3/6 boards. However, other system specific setup should
2342 get added here.
2343
2344 Note: You must still enable the drivers for GPIO and LED support
2345 (GPIO_CS5535 & LEDS_GPIO) to actually use the LEDs
2346
2347 Note: You have to set alix.force=1 for boards with Award BIOS.
2348
2349 config NET5501
2350 bool "Soekris Engineering net5501 System Support (LEDS, GPIO, etc)"
2351 select GPIOLIB
2352 ---help---
2353 This option enables system support for the Soekris Engineering net5501.
2354
2355 config GEOS
2356 bool "Traverse Technologies GEOS System Support (LEDS, GPIO, etc)"
2357 select GPIOLIB
2358 depends on DMI
2359 ---help---
2360 This option enables system support for the Traverse Technologies GEOS.
2361
2362 config TS5500
2363 bool "Technologic Systems TS-5500 platform support"
2364 depends on MELAN
2365 select CHECK_SIGNATURE
2366 select NEW_LEDS
2367 select LEDS_CLASS
2368 ---help---
2369 This option enables system support for the Technologic Systems TS-5500.
2370
2371 endif # X86_32
2372
2373 config AMD_NB
2374 def_bool y
2375 depends on CPU_SUP_AMD && PCI
2376
2377 source "drivers/pcmcia/Kconfig"
2378
2379 source "drivers/pci/hotplug/Kconfig"
2380
2381 config RAPIDIO
2382 tristate "RapidIO support"
2383 depends on PCI
2384 default n
2385 help
2386 If enabled this option will include drivers and the core
2387 infrastructure code to support RapidIO interconnect devices.
2388
2389 source "drivers/rapidio/Kconfig"
2390
2391 config X86_SYSFB
2392 bool "Mark VGA/VBE/EFI FB as generic system framebuffer"
2393 help
2394 Firmwares often provide initial graphics framebuffers so the BIOS,
2395 bootloader or kernel can show basic video-output during boot for
2396 user-guidance and debugging. Historically, x86 used the VESA BIOS
2397 Extensions and EFI-framebuffers for this, which are mostly limited
2398 to x86.
2399 This option, if enabled, marks VGA/VBE/EFI framebuffers as generic
2400 framebuffers so the new generic system-framebuffer drivers can be
2401 used on x86. If the framebuffer is not compatible with the generic
2402 modes, it is adverticed as fallback platform framebuffer so legacy
2403 drivers like efifb, vesafb and uvesafb can pick it up.
2404 If this option is not selected, all system framebuffers are always
2405 marked as fallback platform framebuffers as usual.
2406
2407 Note: Legacy fbdev drivers, including vesafb, efifb, uvesafb, will
2408 not be able to pick up generic system framebuffers if this option
2409 is selected. You are highly encouraged to enable simplefb as
2410 replacement if you select this option. simplefb can correctly deal
2411 with generic system framebuffers. But you should still keep vesafb
2412 and others enabled as fallback if a system framebuffer is
2413 incompatible with simplefb.
2414
2415 If unsure, say Y.
2416
2417 endmenu
2418
2419
2420 menu "Executable file formats / Emulations"
2421
2422 source "fs/Kconfig.binfmt"
2423
2424 config IA32_EMULATION
2425 bool "IA32 Emulation"
2426 depends on X86_64
2427 select BINFMT_ELF
2428 select COMPAT_BINFMT_ELF
2429 select HAVE_UID16
2430 ---help---
2431 Include code to run legacy 32-bit programs under a
2432 64-bit kernel. You should likely turn this on, unless you're
2433 100% sure that you don't have any 32-bit programs left.
2434
2435 config IA32_AOUT
2436 tristate "IA32 a.out support"
2437 depends on IA32_EMULATION
2438 ---help---
2439 Support old a.out binaries in the 32bit emulation.
2440
2441 config X86_X32
2442 bool "x32 ABI for 64-bit mode"
2443 depends on X86_64 && IA32_EMULATION
2444 ---help---
2445 Include code to run binaries for the x32 native 32-bit ABI
2446 for 64-bit processors. An x32 process gets access to the
2447 full 64-bit register file and wide data path while leaving
2448 pointers at 32 bits for smaller memory footprint.
2449
2450 You will need a recent binutils (2.22 or later) with
2451 elf32_x86_64 support enabled to compile a kernel with this
2452 option set.
2453
2454 config COMPAT
2455 def_bool y
2456 depends on IA32_EMULATION || X86_X32
2457 select ARCH_WANT_OLD_COMPAT_IPC
2458
2459 if COMPAT
2460 config COMPAT_FOR_U64_ALIGNMENT
2461 def_bool y
2462
2463 config SYSVIPC_COMPAT
2464 def_bool y
2465 depends on SYSVIPC
2466
2467 config KEYS_COMPAT
2468 def_bool y
2469 depends on KEYS
2470 endif
2471
2472 endmenu
2473
2474
2475 config HAVE_ATOMIC_IOMAP
2476 def_bool y
2477 depends on X86_32
2478
2479 config X86_DEV_DMA_OPS
2480 bool
2481 depends on X86_64 || STA2X11
2482
2483 config X86_DMA_REMAP
2484 bool
2485 depends on STA2X11
2486
2487 config PMC_ATOM
2488 def_bool y
2489 depends on PCI
2490
2491 source "net/Kconfig"
2492
2493 source "drivers/Kconfig"
2494
2495 source "drivers/firmware/Kconfig"
2496
2497 source "fs/Kconfig"
2498
2499 source "arch/x86/Kconfig.debug"
2500
2501 source "security/Kconfig"
2502
2503 source "crypto/Kconfig"
2504
2505 source "arch/x86/kvm/Kconfig"
2506
2507 source "lib/Kconfig"
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