2 mainmenu "Linux Kernel Configuration for x86"
6 bool "64-bit kernel" if ARCH = "x86"
7 default ARCH = "x86_64"
9 Say yes to build a 64-bit kernel - formerly known as x86_64
10 Say no to build a 32-bit kernel - formerly known as i386
21 select HAVE_AOUT if X86_32
24 select HAVE_UNSTABLE_SCHED_CLOCK
27 select HAVE_IOREMAP_PROT
29 select ARCH_WANT_OPTIONAL_GPIOLIB
30 select ARCH_WANT_FRAME_POINTERS
31 select HAVE_KRETPROBES
32 select HAVE_FTRACE_MCOUNT_RECORD
33 select HAVE_DYNAMIC_FTRACE
34 select HAVE_FUNCTION_TRACER
35 select HAVE_FUNCTION_GRAPH_TRACER
36 select HAVE_FUNCTION_TRACE_MCOUNT_TEST
39 select HAVE_ARCH_TRACEHOOK
40 select HAVE_GENERIC_DMA_COHERENT if X86_32
41 select HAVE_EFFICIENT_UNALIGNED_ACCESS
42 select USER_STACKTRACE_SUPPORT
46 default "arch/x86/configs/i386_defconfig" if X86_32
47 default "arch/x86/configs/x86_64_defconfig" if X86_64
52 config GENERIC_CMOS_UPDATE
55 config CLOCKSOURCE_WATCHDOG
58 config GENERIC_CLOCKEVENTS
61 config GENERIC_CLOCKEVENTS_BROADCAST
63 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
65 config LOCKDEP_SUPPORT
68 config STACKTRACE_SUPPORT
71 config HAVE_LATENCYTOP_SUPPORT
74 config FAST_CMPXCHG_LOCAL
87 config GENERIC_ISA_DMA
96 select GENERIC_BUG_RELATIVE_POINTERS if X86_64
98 config GENERIC_BUG_RELATIVE_POINTERS
101 config GENERIC_HWEIGHT
107 config ARCH_MAY_HAVE_PC_FDC
110 config RWSEM_GENERIC_SPINLOCK
113 config RWSEM_XCHGADD_ALGORITHM
116 config ARCH_HAS_CPU_IDLE_WAIT
119 config GENERIC_CALIBRATE_DELAY
122 config GENERIC_TIME_VSYSCALL
126 config ARCH_HAS_CPU_RELAX
129 config ARCH_HAS_DEFAULT_IDLE
132 config ARCH_HAS_CACHE_LINE_SIZE
135 config HAVE_SETUP_PER_CPU_AREA
138 config HAVE_CPUMASK_OF_CPU_MAP
141 config ARCH_HIBERNATION_POSSIBLE
145 config ARCH_SUSPEND_POSSIBLE
152 config ARCH_POPULATES_NODE_MAP
159 config ARCH_SUPPORTS_OPTIMIZED_INLINING
162 # Use the generic interrupt handling code in kernel/irq/:
163 config GENERIC_HARDIRQS
167 config GENERIC_IRQ_PROBE
171 config GENERIC_PENDING_IRQ
173 depends on GENERIC_HARDIRQS && SMP
176 config USE_GENERIC_SMP_HELPERS
182 depends on X86_32 && SMP
186 depends on X86_64 && SMP
193 config X86_TRAMPOLINE
195 depends on SMP || (64BIT && ACPI_SLEEP)
200 source "init/Kconfig"
201 source "kernel/Kconfig.freezer"
203 menu "Processor type and features"
205 source "kernel/time/Kconfig"
208 bool "Symmetric multi-processing support"
210 This enables support for systems with more than one CPU. If you have
211 a system with only one CPU, like most personal computers, say N. If
212 you have a system with more than one CPU, say Y.
214 If you say N here, the kernel will run on single and multiprocessor
215 machines, but will use only one CPU of a multiprocessor machine. If
216 you say Y here, the kernel will run on many, but not all,
217 singleprocessor machines. On a singleprocessor machine, the kernel
218 will run faster if you say N here.
220 Note that if you say Y here and choose architecture "586" or
221 "Pentium" under "Processor family", the kernel will not work on 486
222 architectures. Similarly, multiprocessor kernels for the "PPro"
223 architecture may not work on all Pentium based boards.
225 People using multiprocessor machines who say Y here should also say
226 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
227 Management" code will be disabled if you say Y here.
229 See also <file:Documentation/i386/IO-APIC.txt>,
230 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
231 <http://www.tldp.org/docs.html#howto>.
233 If you don't know what to do here, say N.
236 bool "Support sparse irq numbering"
237 depends on PCI_MSI || HT_IRQ
239 This enables support for sparse irqs. This is useful for distro
240 kernels that want to define a high CONFIG_NR_CPUS value but still
241 want to have low kernel memory footprint on smaller machines.
243 ( Sparse IRQs can also be beneficial on NUMA boxes, as they spread
244 out the irq_desc[] array in a more NUMA-friendly way. )
246 If you don't know what to do here, say N.
248 config NUMA_MIGRATE_IRQ_DESC
249 bool "Move irq desc when changing irq smp_affinity"
250 depends on SPARSE_IRQ && NUMA
253 This enables moving irq_desc to cpu/node that irq will use handled.
255 If you don't know what to do here, say N.
258 bool "Enable MPS table" if ACPI
260 depends on X86_LOCAL_APIC
262 For old smp systems that do not have proper acpi support. Newer systems
263 (esp with 64bit cpus) with acpi support, MADT and DSDT will override it
266 bool "Support for big SMP systems with more than 8 CPUs"
267 depends on X86_32 && SMP
269 This option is needed for the systems that have more than 8 CPUs
271 config X86_NON_STANDARD
272 bool "Support for non-standard x86 platforms"
274 If you disable this option then the kernel will only support
275 standard PC platforms. (which covers the vast majority of
278 If you enable this option then you'll be able to select a number
279 of less common non-PC x86 platforms: VisWS, RDC321, SGI/UV.
281 If you have one of these systems, or if you want to build a
282 generic distribution kernel, say Y here - otherwise say N.
285 bool "SGI 320/540 (Visual Workstation)"
286 depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
287 depends on X86_NON_STANDARD
289 The SGI Visual Workstation series is an IA32-based workstation
290 based on SGI systems chips with some legacy PC hardware attached.
292 Say Y here to create a kernel to run on the SGI 320 or 540.
294 A kernel compiled for the Visual Workstation will run on general
295 PCs as well. See <file:Documentation/sgi-visws.txt> for details.
298 bool "RDC R-321x SoC"
300 depends on X86_NON_STANDARD
302 select X86_REBOOTFIXUPS
304 This option is needed for RDC R-321x system-on-chip, also known
306 If you don't have one of these chips, you should say N here.
309 bool "SGI Ultraviolet"
311 depends on X86_NON_STANDARD
313 This option is needed in order to support SGI Ultraviolet systems.
314 If you don't have one of these, you should say N here.
317 bool "Support for ScaleMP vSMP"
319 depends on X86_64 && PCI
320 depends on X86_NON_STANDARD
322 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
323 supposed to run on these EM64T-based machines. Only choose this option
324 if you have one of these machines.
329 depends on X86_NON_STANDARD
331 Select this for an AMD Elan processor.
333 Do not use this option for K6/Athlon/Opteron processors!
335 If unsure, choose "PC-compatible" instead.
337 config X86_32_NON_STANDARD
338 bool "Support non-standard 32-bit SMP architectures"
339 depends on X86_32 && SMP
340 depends on X86_NON_STANDARD
342 This option compiles in the NUMAQ, Summit, bigsmp, ES7000, default
343 subarchitectures. It is intended for a generic binary kernel.
344 if you select them all, kernel will probe it one by one. and will
348 bool "NUMAQ (IBM/Sequent)"
349 depends on X86_32_NON_STANDARD
353 This option is used for getting Linux to run on a NUMAQ (IBM/Sequent)
354 NUMA multiquad box. This changes the way that processors are
355 bootstrapped, and uses Clustered Logical APIC addressing mode instead
356 of Flat Logical. You will need a new lynxer.elf file to flash your
357 firmware with - send email to <Martin.Bligh@us.ibm.com>.
360 bool "Summit/EXA (IBM x440)"
361 depends on X86_32_NON_STANDARD
363 This option is needed for IBM systems that use the Summit/EXA chipset.
364 In particular, it is needed for the x440.
367 bool "Support for Unisys ES7000 IA32 series"
368 depends on X86_32_NON_STANDARD && X86_BIGSMP
370 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
371 supposed to run on an IA32-based Unisys ES7000 system.
375 depends on SMP && !PCI && BROKEN
376 depends on X86_32_NON_STANDARD
378 Voyager is an MCA-based 32-way capable SMP architecture proprietary
379 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
383 If you do not specifically know you have a Voyager based machine,
384 say N here, otherwise the kernel you build will not be bootable.
386 config SCHED_OMIT_FRAME_POINTER
388 prompt "Single-depth WCHAN output"
391 Calculate simpler /proc/<PID>/wchan values. If this option
392 is disabled then wchan values will recurse back to the
393 caller function. This provides more accurate wchan values,
394 at the expense of slightly more scheduling overhead.
396 If in doubt, say "Y".
398 menuconfig PARAVIRT_GUEST
399 bool "Paravirtualized guest support"
401 Say Y here to get to see options related to running Linux under
402 various hypervisors. This option alone does not add any kernel code.
404 If you say N, all options in this submenu will be skipped and disabled.
408 source "arch/x86/xen/Kconfig"
411 bool "VMI Guest support"
415 VMI provides a paravirtualized interface to the VMware ESX server
416 (it could be used by other hypervisors in theory too, but is not
417 at the moment), by linking the kernel to a GPL-ed ROM module
418 provided by the hypervisor.
421 bool "KVM paravirtualized clock"
423 select PARAVIRT_CLOCK
425 Turning on this option will allow you to run a paravirtualized clock
426 when running over the KVM hypervisor. Instead of relying on a PIT
427 (or probably other) emulation by the underlying device model, the host
428 provides the guest with timing infrastructure such as time of day, and
432 bool "KVM Guest support"
435 This option enables various optimizations for running under the KVM
438 source "arch/x86/lguest/Kconfig"
441 bool "Enable paravirtualization code"
443 This changes the kernel so it can modify itself when it is run
444 under a hypervisor, potentially improving performance significantly
445 over full virtualization. However, when run without a hypervisor
446 the kernel is theoretically slower and slightly larger.
448 config PARAVIRT_CLOCK
454 config PARAVIRT_DEBUG
455 bool "paravirt-ops debugging"
456 depends on PARAVIRT && DEBUG_KERNEL
458 Enable to debug paravirt_ops internals. Specifically, BUG if
459 a paravirt_op is missing when it is called.
464 This option adds a kernel parameter 'memtest', which allows memtest
466 memtest=0, mean disabled; -- default
467 memtest=1, mean do 1 test pattern;
469 memtest=4, mean do 4 test patterns.
470 If you are unsure how to answer this question, answer N.
472 config X86_SUMMIT_NUMA
474 depends on X86_32 && NUMA && X86_32_NON_STANDARD
476 config X86_CYCLONE_TIMER
478 depends on X86_32_NON_STANDARD
480 source "arch/x86/Kconfig.cpu"
484 prompt "HPET Timer Support" if X86_32
486 Use the IA-PC HPET (High Precision Event Timer) to manage
487 time in preference to the PIT and RTC, if a HPET is
489 HPET is the next generation timer replacing legacy 8254s.
490 The HPET provides a stable time base on SMP
491 systems, unlike the TSC, but it is more expensive to access,
492 as it is off-chip. You can find the HPET spec at
493 <http://www.intel.com/hardwaredesign/hpetspec_1.pdf>.
495 You can safely choose Y here. However, HPET will only be
496 activated if the platform and the BIOS support this feature.
497 Otherwise the 8254 will be used for timing services.
499 Choose N to continue using the legacy 8254 timer.
501 config HPET_EMULATE_RTC
503 depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
505 # Mark as embedded because too many people got it wrong.
506 # The code disables itself when not needed.
509 bool "Enable DMI scanning" if EMBEDDED
511 Enabled scanning of DMI to identify machine quirks. Say Y
512 here unless you have verified that your setup is not
513 affected by entries in the DMI blacklist. Required by PNP
517 bool "GART IOMMU support" if EMBEDDED
521 depends on X86_64 && PCI
523 Support for full DMA access of devices with 32bit memory access only
524 on systems with more than 3GB. This is usually needed for USB,
525 sound, many IDE/SATA chipsets and some other devices.
526 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
527 based hardware IOMMU and a software bounce buffer based IOMMU used
528 on Intel systems and as fallback.
529 The code is only active when needed (enough memory and limited
530 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
534 bool "IBM Calgary IOMMU support"
536 depends on X86_64 && PCI && EXPERIMENTAL
538 Support for hardware IOMMUs in IBM's xSeries x366 and x460
539 systems. Needed to run systems with more than 3GB of memory
540 properly with 32-bit PCI devices that do not support DAC
541 (Double Address Cycle). Calgary also supports bus level
542 isolation, where all DMAs pass through the IOMMU. This
543 prevents them from going anywhere except their intended
544 destination. This catches hard-to-find kernel bugs and
545 mis-behaving drivers and devices that do not use the DMA-API
546 properly to set up their DMA buffers. The IOMMU can be
547 turned off at boot time with the iommu=off parameter.
548 Normally the kernel will make the right choice by itself.
551 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
553 prompt "Should Calgary be enabled by default?"
554 depends on CALGARY_IOMMU
556 Should Calgary be enabled by default? if you choose 'y', Calgary
557 will be used (if it exists). If you choose 'n', Calgary will not be
558 used even if it exists. If you choose 'n' and would like to use
559 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
563 bool "AMD IOMMU support"
566 depends on X86_64 && PCI && ACPI
568 With this option you can enable support for AMD IOMMU hardware in
569 your system. An IOMMU is a hardware component which provides
570 remapping of DMA memory accesses from devices. With an AMD IOMMU you
571 can isolate the the DMA memory of different devices and protect the
572 system from misbehaving device drivers or hardware.
574 You can find out if your system has an AMD IOMMU if you look into
575 your BIOS for an option to enable it or if you have an IVRS ACPI
578 config AMD_IOMMU_STATS
579 bool "Export AMD IOMMU statistics to debugfs"
583 This option enables code in the AMD IOMMU driver to collect various
584 statistics about whats happening in the driver and exports that
585 information to userspace via debugfs.
588 # need this always selected by IOMMU for the VIA workaround
592 Support for software bounce buffers used on x86-64 systems
593 which don't have a hardware IOMMU (e.g. the current generation
594 of Intel's x86-64 CPUs). Using this PCI devices which can only
595 access 32-bits of memory can be used on systems with more than
596 3 GB of memory. If unsure, say Y.
599 def_bool (CALGARY_IOMMU || GART_IOMMU || SWIOTLB || AMD_IOMMU)
602 def_bool (AMD_IOMMU || DMAR)
605 bool "Configure Maximum number of SMP Processors and NUMA Nodes"
606 depends on X86_64 && SMP && DEBUG_KERNEL && EXPERIMENTAL
607 select CPUMASK_OFFSTACK
610 Configure maximum number of CPUS and NUMA Nodes for this architecture.
614 int "Maximum number of CPUs" if SMP && !MAXSMP
615 range 2 512 if SMP && !MAXSMP
617 default "4096" if MAXSMP
618 default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000)
621 This allows you to specify the maximum number of CPUs which this
622 kernel will support. The maximum supported value is 512 and the
623 minimum value which makes sense is 2.
625 This is purely to save memory - each supported CPU adds
626 approximately eight kilobytes to the kernel image.
629 bool "SMT (Hyperthreading) scheduler support"
632 SMT scheduler support improves the CPU scheduler's decision making
633 when dealing with Intel Pentium 4 chips with HyperThreading at a
634 cost of slightly increased overhead in some places. If unsure say
639 prompt "Multi-core scheduler support"
642 Multi-core scheduler support improves the CPU scheduler's decision
643 making when dealing with multi-core CPU chips at a cost of slightly
644 increased overhead in some places. If unsure say N here.
646 source "kernel/Kconfig.preempt"
649 bool "Local APIC support on uniprocessors"
650 depends on X86_32 && !SMP && !X86_32_NON_STANDARD
652 A local APIC (Advanced Programmable Interrupt Controller) is an
653 integrated interrupt controller in the CPU. If you have a single-CPU
654 system which has a processor with a local APIC, you can say Y here to
655 enable and use it. If you say Y here even though your machine doesn't
656 have a local APIC, then the kernel will still run with no slowdown at
657 all. The local APIC supports CPU-generated self-interrupts (timer,
658 performance counters), and the NMI watchdog which detects hard
662 bool "IO-APIC support on uniprocessors"
663 depends on X86_UP_APIC
665 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
666 SMP-capable replacement for PC-style interrupt controllers. Most
667 SMP systems and many recent uniprocessor systems have one.
669 If you have a single-CPU system with an IO-APIC, you can say Y here
670 to use it. If you say Y here even though your machine doesn't have
671 an IO-APIC, then the kernel will still run with no slowdown at all.
673 config X86_LOCAL_APIC
675 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
679 depends on X86_64 || SMP || X86_32_NON_STANDARD || X86_UP_APIC
681 config X86_VISWS_APIC
683 depends on X86_32 && X86_VISWS
685 config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
686 bool "Reroute for broken boot IRQs"
688 depends on X86_IO_APIC
690 This option enables a workaround that fixes a source of
691 spurious interrupts. This is recommended when threaded
692 interrupt handling is used on systems where the generation of
693 superfluous "boot interrupts" cannot be disabled.
695 Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
696 entry in the chipset's IO-APIC is masked (as, e.g. the RT
697 kernel does during interrupt handling). On chipsets where this
698 boot IRQ generation cannot be disabled, this workaround keeps
699 the original IRQ line masked so that only the equivalent "boot
700 IRQ" is delivered to the CPUs. The workaround also tells the
701 kernel to set up the IRQ handler on the boot IRQ line. In this
702 way only one interrupt is delivered to the kernel. Otherwise
703 the spurious second interrupt may cause the kernel to bring
704 down (vital) interrupt lines.
706 Only affects "broken" chipsets. Interrupt sharing may be
707 increased on these systems.
710 bool "Machine Check Exception"
712 Machine Check Exception support allows the processor to notify the
713 kernel if it detects a problem (e.g. overheating, component failure).
714 The action the kernel takes depends on the severity of the problem,
715 ranging from a warning message on the console, to halting the machine.
716 Your processor must be a Pentium or newer to support this - check the
717 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
718 have a design flaw which leads to false MCE events - hence MCE is
719 disabled on all P5 processors, unless explicitly enabled with "mce"
720 as a boot argument. Similarly, if MCE is built in and creates a
721 problem on some new non-standard machine, you can boot with "nomce"
722 to disable it. MCE support simply ignores non-MCE processors like
723 the 386 and 486, so nearly everyone can say Y here.
727 prompt "Intel MCE features"
728 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
730 Additional support for intel specific MCE features such as
735 prompt "AMD MCE features"
736 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
738 Additional support for AMD specific MCE features such as
739 the DRAM Error Threshold.
741 config X86_MCE_NONFATAL
742 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
743 depends on X86_32 && X86_MCE
745 Enabling this feature starts a timer that triggers every 5 seconds which
746 will look at the machine check registers to see if anything happened.
747 Non-fatal problems automatically get corrected (but still logged).
748 Disable this if you don't want to see these messages.
749 Seeing the messages this option prints out may be indicative of dying
750 or out-of-spec (ie, overclocked) hardware.
751 This option only does something on certain CPUs.
752 (AMD Athlon/Duron and Intel Pentium 4)
754 config X86_MCE_P4THERMAL
755 bool "check for P4 thermal throttling interrupt."
756 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP)
758 Enabling this feature will cause a message to be printed when the P4
759 enters thermal throttling.
762 bool "Enable VM86 support" if EMBEDDED
766 This option is required by programs like DOSEMU to run 16-bit legacy
767 code on X86 processors. It also may be needed by software like
768 XFree86 to initialize some video cards via BIOS. Disabling this
769 option saves about 6k.
772 tristate "Toshiba Laptop support"
775 This adds a driver to safely access the System Management Mode of
776 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
777 not work on models with a Phoenix BIOS. The System Management Mode
778 is used to set the BIOS and power saving options on Toshiba portables.
780 For information on utilities to make use of this driver see the
781 Toshiba Linux utilities web site at:
782 <http://www.buzzard.org.uk/toshiba/>.
784 Say Y if you intend to run this kernel on a Toshiba portable.
788 tristate "Dell laptop support"
790 This adds a driver to safely access the System Management Mode
791 of the CPU on the Dell Inspiron 8000. The System Management Mode
792 is used to read cpu temperature and cooling fan status and to
793 control the fans on the I8K portables.
795 This driver has been tested only on the Inspiron 8000 but it may
796 also work with other Dell laptops. You can force loading on other
797 models by passing the parameter `force=1' to the module. Use at
800 For information on utilities to make use of this driver see the
801 I8K Linux utilities web site at:
802 <http://people.debian.org/~dz/i8k/>
804 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
807 config X86_REBOOTFIXUPS
808 bool "Enable X86 board specific fixups for reboot"
811 This enables chipset and/or board specific fixups to be done
812 in order to get reboot to work correctly. This is only needed on
813 some combinations of hardware and BIOS. The symptom, for which
814 this config is intended, is when reboot ends with a stalled/hung
817 Currently, the only fixup is for the Geode machines using
818 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
820 Say Y if you want to enable the fixup. Currently, it's safe to
821 enable this option even if you don't need it.
825 tristate "/dev/cpu/microcode - microcode support"
828 If you say Y here, you will be able to update the microcode on
829 certain Intel and AMD processors. The Intel support is for the
830 IA32 family, e.g. Pentium Pro, Pentium II, Pentium III,
831 Pentium 4, Xeon etc. The AMD support is for family 0x10 and
832 0x11 processors, e.g. Opteron, Phenom and Turion 64 Ultra.
833 You will obviously need the actual microcode binary data itself
834 which is not shipped with the Linux kernel.
836 This option selects the general module only, you need to select
837 at least one vendor specific module as well.
839 To compile this driver as a module, choose M here: the
840 module will be called microcode.
842 config MICROCODE_INTEL
843 bool "Intel microcode patch loading support"
848 This options enables microcode patch loading support for Intel
851 For latest news and information on obtaining all the required
852 Intel ingredients for this driver, check:
853 <http://www.urbanmyth.org/microcode/>.
856 bool "AMD microcode patch loading support"
860 If you select this option, microcode patch loading support for AMD
861 processors will be enabled.
863 config MICROCODE_OLD_INTERFACE
868 tristate "/dev/cpu/*/msr - Model-specific register support"
870 This device gives privileged processes access to the x86
871 Model-Specific Registers (MSRs). It is a character device with
872 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
873 MSR accesses are directed to a specific CPU on multi-processor
877 tristate "/dev/cpu/*/cpuid - CPU information support"
879 This device gives processes access to the x86 CPUID instruction to
880 be executed on a specific processor. It is a character device
881 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
885 prompt "High Memory Support"
886 default HIGHMEM4G if !X86_NUMAQ
887 default HIGHMEM64G if X86_NUMAQ
892 depends on !X86_NUMAQ
894 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
895 However, the address space of 32-bit x86 processors is only 4
896 Gigabytes large. That means that, if you have a large amount of
897 physical memory, not all of it can be "permanently mapped" by the
898 kernel. The physical memory that's not permanently mapped is called
901 If you are compiling a kernel which will never run on a machine with
902 more than 1 Gigabyte total physical RAM, answer "off" here (default
903 choice and suitable for most users). This will result in a "3GB/1GB"
904 split: 3GB are mapped so that each process sees a 3GB virtual memory
905 space and the remaining part of the 4GB virtual memory space is used
906 by the kernel to permanently map as much physical memory as
909 If the machine has between 1 and 4 Gigabytes physical RAM, then
912 If more than 4 Gigabytes is used then answer "64GB" here. This
913 selection turns Intel PAE (Physical Address Extension) mode on.
914 PAE implements 3-level paging on IA32 processors. PAE is fully
915 supported by Linux, PAE mode is implemented on all recent Intel
916 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
917 then the kernel will not boot on CPUs that don't support PAE!
919 The actual amount of total physical memory will either be
920 auto detected or can be forced by using a kernel command line option
921 such as "mem=256M". (Try "man bootparam" or see the documentation of
922 your boot loader (lilo or loadlin) about how to pass options to the
923 kernel at boot time.)
925 If unsure, say "off".
929 depends on !X86_NUMAQ
931 Select this if you have a 32-bit processor and between 1 and 4
932 gigabytes of physical RAM.
936 depends on !M386 && !M486
939 Select this if you have a 32-bit processor and more than 4
940 gigabytes of physical RAM.
945 depends on EXPERIMENTAL
946 prompt "Memory split" if EMBEDDED
950 Select the desired split between kernel and user memory.
952 If the address range available to the kernel is less than the
953 physical memory installed, the remaining memory will be available
954 as "high memory". Accessing high memory is a little more costly
955 than low memory, as it needs to be mapped into the kernel first.
956 Note that increasing the kernel address space limits the range
957 available to user programs, making the address space there
958 tighter. Selecting anything other than the default 3G/1G split
959 will also likely make your kernel incompatible with binary-only
962 If you are not absolutely sure what you are doing, leave this
966 bool "3G/1G user/kernel split"
967 config VMSPLIT_3G_OPT
969 bool "3G/1G user/kernel split (for full 1G low memory)"
971 bool "2G/2G user/kernel split"
972 config VMSPLIT_2G_OPT
974 bool "2G/2G user/kernel split (for full 2G low memory)"
976 bool "1G/3G user/kernel split"
981 default 0xB0000000 if VMSPLIT_3G_OPT
982 default 0x80000000 if VMSPLIT_2G
983 default 0x78000000 if VMSPLIT_2G_OPT
984 default 0x40000000 if VMSPLIT_1G
990 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
993 bool "PAE (Physical Address Extension) Support"
994 depends on X86_32 && !HIGHMEM4G
996 PAE is required for NX support, and furthermore enables
997 larger swapspace support for non-overcommit purposes. It
998 has the cost of more pagetable lookup overhead, and also
999 consumes more pagetable space per process.
1001 config ARCH_PHYS_ADDR_T_64BIT
1002 def_bool X86_64 || X86_PAE
1004 config DIRECT_GBPAGES
1005 bool "Enable 1GB pages for kernel pagetables" if EMBEDDED
1009 Allow the kernel linear mapping to use 1GB pages on CPUs that
1010 support it. This can improve the kernel's performance a tiny bit by
1011 reducing TLB pressure. If in doubt, say "Y".
1013 # Common NUMA Features
1015 bool "Numa Memory Allocation and Scheduler Support"
1017 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
1018 default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
1020 Enable NUMA (Non Uniform Memory Access) support.
1022 The kernel will try to allocate memory used by a CPU on the
1023 local memory controller of the CPU and add some more
1024 NUMA awareness to the kernel.
1026 For 64-bit this is recommended if the system is Intel Core i7
1027 (or later), AMD Opteron, or EM64T NUMA.
1029 For 32-bit this is only needed on (rare) 32-bit-only platforms
1030 that support NUMA topologies, such as NUMAQ / Summit, or if you
1031 boot a 32-bit kernel on a 64-bit NUMA platform.
1033 Otherwise, you should say N.
1035 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
1036 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
1040 prompt "Old style AMD Opteron NUMA detection"
1041 depends on X86_64 && NUMA && PCI
1043 Enable K8 NUMA node topology detection. You should say Y here if
1044 you have a multi processor AMD K8 system. This uses an old
1045 method to read the NUMA configuration directly from the builtin
1046 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
1047 instead, which also takes priority if both are compiled in.
1049 config X86_64_ACPI_NUMA
1051 prompt "ACPI NUMA detection"
1052 depends on X86_64 && NUMA && ACPI && PCI
1055 Enable ACPI SRAT based node topology detection.
1057 # Some NUMA nodes have memory ranges that span
1058 # other nodes. Even though a pfn is valid and
1059 # between a node's start and end pfns, it may not
1060 # reside on that node. See memmap_init_zone()
1062 config NODES_SPAN_OTHER_NODES
1064 depends on X86_64_ACPI_NUMA
1067 bool "NUMA emulation"
1068 depends on X86_64 && NUMA
1070 Enable NUMA emulation. A flat machine will be split
1071 into virtual nodes when booted with "numa=fake=N", where N is the
1072 number of nodes. This is only useful for debugging.
1075 int "Maximum NUMA Nodes (as a power of 2)" if !MAXSMP
1077 default "9" if MAXSMP
1078 default "6" if X86_64
1079 default "4" if X86_NUMAQ
1081 depends on NEED_MULTIPLE_NODES
1083 Specify the maximum number of NUMA Nodes available on the target
1084 system. Increases memory reserved to accomodate various tables.
1086 config HAVE_ARCH_BOOTMEM_NODE
1088 depends on X86_32 && NUMA
1090 config ARCH_HAVE_MEMORY_PRESENT
1092 depends on X86_32 && DISCONTIGMEM
1094 config NEED_NODE_MEMMAP_SIZE
1096 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
1098 config HAVE_ARCH_ALLOC_REMAP
1100 depends on X86_32 && NUMA
1102 config ARCH_FLATMEM_ENABLE
1104 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && !NUMA
1106 config ARCH_DISCONTIGMEM_ENABLE
1108 depends on NUMA && X86_32
1110 config ARCH_DISCONTIGMEM_DEFAULT
1112 depends on NUMA && X86_32
1114 config ARCH_SPARSEMEM_DEFAULT
1118 config ARCH_SPARSEMEM_ENABLE
1120 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_32) || X86_32_NON_STANDARD
1121 select SPARSEMEM_STATIC if X86_32
1122 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
1124 config ARCH_SELECT_MEMORY_MODEL
1126 depends on ARCH_SPARSEMEM_ENABLE
1128 config ARCH_MEMORY_PROBE
1130 depends on MEMORY_HOTPLUG
1135 bool "Allocate 3rd-level pagetables from highmem"
1136 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
1138 The VM uses one page table entry for each page of physical memory.
1139 For systems with a lot of RAM, this can be wasteful of precious
1140 low memory. Setting this option will put user-space page table
1141 entries in high memory.
1143 config X86_CHECK_BIOS_CORRUPTION
1144 bool "Check for low memory corruption"
1146 Periodically check for memory corruption in low memory, which
1147 is suspected to be caused by BIOS. Even when enabled in the
1148 configuration, it is disabled at runtime. Enable it by
1149 setting "memory_corruption_check=1" on the kernel command
1150 line. By default it scans the low 64k of memory every 60
1151 seconds; see the memory_corruption_check_size and
1152 memory_corruption_check_period parameters in
1153 Documentation/kernel-parameters.txt to adjust this.
1155 When enabled with the default parameters, this option has
1156 almost no overhead, as it reserves a relatively small amount
1157 of memory and scans it infrequently. It both detects corruption
1158 and prevents it from affecting the running system.
1160 It is, however, intended as a diagnostic tool; if repeatable
1161 BIOS-originated corruption always affects the same memory,
1162 you can use memmap= to prevent the kernel from using that
1165 config X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
1166 bool "Set the default setting of memory_corruption_check"
1167 depends on X86_CHECK_BIOS_CORRUPTION
1170 Set whether the default state of memory_corruption_check is
1173 config X86_RESERVE_LOW_64K
1174 bool "Reserve low 64K of RAM on AMI/Phoenix BIOSen"
1177 Reserve the first 64K of physical RAM on BIOSes that are known
1178 to potentially corrupt that memory range. A numbers of BIOSes are
1179 known to utilize this area during suspend/resume, so it must not
1180 be used by the kernel.
1182 Set this to N if you are absolutely sure that you trust the BIOS
1183 to get all its memory reservations and usages right.
1185 If you have doubts about the BIOS (e.g. suspend/resume does not
1186 work or there's kernel crashes after certain hardware hotplug
1187 events) and it's not AMI or Phoenix, then you might want to enable
1188 X86_CHECK_BIOS_CORRUPTION=y to allow the kernel to check typical
1189 corruption patterns.
1193 config MATH_EMULATION
1195 prompt "Math emulation" if X86_32
1197 Linux can emulate a math coprocessor (used for floating point
1198 operations) if you don't have one. 486DX and Pentium processors have
1199 a math coprocessor built in, 486SX and 386 do not, unless you added
1200 a 487DX or 387, respectively. (The messages during boot time can
1201 give you some hints here ["man dmesg"].) Everyone needs either a
1202 coprocessor or this emulation.
1204 If you don't have a math coprocessor, you need to say Y here; if you
1205 say Y here even though you have a coprocessor, the coprocessor will
1206 be used nevertheless. (This behavior can be changed with the kernel
1207 command line option "no387", which comes handy if your coprocessor
1208 is broken. Try "man bootparam" or see the documentation of your boot
1209 loader (lilo or loadlin) about how to pass options to the kernel at
1210 boot time.) This means that it is a good idea to say Y here if you
1211 intend to use this kernel on different machines.
1213 More information about the internals of the Linux math coprocessor
1214 emulation can be found in <file:arch/x86/math-emu/README>.
1216 If you are not sure, say Y; apart from resulting in a 66 KB bigger
1217 kernel, it won't hurt.
1220 bool "MTRR (Memory Type Range Register) support"
1222 On Intel P6 family processors (Pentium Pro, Pentium II and later)
1223 the Memory Type Range Registers (MTRRs) may be used to control
1224 processor access to memory ranges. This is most useful if you have
1225 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
1226 allows bus write transfers to be combined into a larger transfer
1227 before bursting over the PCI/AGP bus. This can increase performance
1228 of image write operations 2.5 times or more. Saying Y here creates a
1229 /proc/mtrr file which may be used to manipulate your processor's
1230 MTRRs. Typically the X server should use this.
1232 This code has a reasonably generic interface so that similar
1233 control registers on other processors can be easily supported
1236 The Cyrix 6x86, 6x86MX and M II processors have Address Range
1237 Registers (ARRs) which provide a similar functionality to MTRRs. For
1238 these, the ARRs are used to emulate the MTRRs.
1239 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
1240 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
1241 write-combining. All of these processors are supported by this code
1242 and it makes sense to say Y here if you have one of them.
1244 Saying Y here also fixes a problem with buggy SMP BIOSes which only
1245 set the MTRRs for the boot CPU and not for the secondary CPUs. This
1246 can lead to all sorts of problems, so it's good to say Y here.
1248 You can safely say Y even if your machine doesn't have MTRRs, you'll
1249 just add about 9 KB to your kernel.
1251 See <file:Documentation/x86/mtrr.txt> for more information.
1253 config MTRR_SANITIZER
1255 prompt "MTRR cleanup support"
1258 Convert MTRR layout from continuous to discrete, so X drivers can
1259 add writeback entries.
1261 Can be disabled with disable_mtrr_cleanup on the kernel command line.
1262 The largest mtrr entry size for a continous block can be set with
1267 config MTRR_SANITIZER_ENABLE_DEFAULT
1268 int "MTRR cleanup enable value (0-1)"
1271 depends on MTRR_SANITIZER
1273 Enable mtrr cleanup default value
1275 config MTRR_SANITIZER_SPARE_REG_NR_DEFAULT
1276 int "MTRR cleanup spare reg num (0-7)"
1279 depends on MTRR_SANITIZER
1281 mtrr cleanup spare entries default, it can be changed via
1282 mtrr_spare_reg_nr=N on the kernel command line.
1286 prompt "x86 PAT support"
1289 Use PAT attributes to setup page level cache control.
1291 PATs are the modern equivalents of MTRRs and are much more
1292 flexible than MTRRs.
1294 Say N here if you see bootup problems (boot crash, boot hang,
1295 spontaneous reboots) or a non-working video driver.
1300 bool "EFI runtime service support"
1303 This enables the kernel to use EFI runtime services that are
1304 available (such as the EFI variable services).
1306 This option is only useful on systems that have EFI firmware.
1307 In addition, you should use the latest ELILO loader available
1308 at <http://elilo.sourceforge.net> in order to take advantage
1309 of EFI runtime services. However, even with this option, the
1310 resultant kernel should continue to boot on existing non-EFI
1315 prompt "Enable seccomp to safely compute untrusted bytecode"
1317 This kernel feature is useful for number crunching applications
1318 that may need to compute untrusted bytecode during their
1319 execution. By using pipes or other transports made available to
1320 the process as file descriptors supporting the read/write
1321 syscalls, it's possible to isolate those applications in
1322 their own address space using seccomp. Once seccomp is
1323 enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
1324 and the task is only allowed to execute a few safe syscalls
1325 defined by each seccomp mode.
1327 If unsure, say Y. Only embedded should say N here.
1329 config CC_STACKPROTECTOR_ALL
1332 config CC_STACKPROTECTOR
1333 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1335 select CC_STACKPROTECTOR_ALL
1337 This option turns on the -fstack-protector GCC feature. This
1338 feature puts, at the beginning of functions, a canary value on
1339 the stack just before the return address, and validates
1340 the value just before actually returning. Stack based buffer
1341 overflows (that need to overwrite this return address) now also
1342 overwrite the canary, which gets detected and the attack is then
1343 neutralized via a kernel panic.
1345 This feature requires gcc version 4.2 or above, or a distribution
1346 gcc with the feature backported. Older versions are automatically
1347 detected and for those versions, this configuration option is
1348 ignored. (and a warning is printed during bootup)
1350 source kernel/Kconfig.hz
1353 bool "kexec system call"
1355 kexec is a system call that implements the ability to shutdown your
1356 current kernel, and to start another kernel. It is like a reboot
1357 but it is independent of the system firmware. And like a reboot
1358 you can start any kernel with it, not just Linux.
1360 The name comes from the similarity to the exec system call.
1362 It is an ongoing process to be certain the hardware in a machine
1363 is properly shutdown, so do not be surprised if this code does not
1364 initially work for you. It may help to enable device hotplugging
1365 support. As of this writing the exact hardware interface is
1366 strongly in flux, so no good recommendation can be made.
1369 bool "kernel crash dumps"
1370 depends on X86_64 || (X86_32 && HIGHMEM)
1372 Generate crash dump after being started by kexec.
1373 This should be normally only set in special crash dump kernels
1374 which are loaded in the main kernel with kexec-tools into
1375 a specially reserved region and then later executed after
1376 a crash by kdump/kexec. The crash dump kernel must be compiled
1377 to a memory address not used by the main kernel or BIOS using
1378 PHYSICAL_START, or it must be built as a relocatable image
1379 (CONFIG_RELOCATABLE=y).
1380 For more details see Documentation/kdump/kdump.txt
1383 bool "kexec jump (EXPERIMENTAL)"
1384 depends on EXPERIMENTAL
1385 depends on KEXEC && HIBERNATION && X86_32
1387 Jump between original kernel and kexeced kernel and invoke
1388 code in physical address mode via KEXEC
1390 config PHYSICAL_START
1391 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1392 default "0x1000000" if X86_NUMAQ
1393 default "0x200000" if X86_64
1396 This gives the physical address where the kernel is loaded.
1398 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1399 bzImage will decompress itself to above physical address and
1400 run from there. Otherwise, bzImage will run from the address where
1401 it has been loaded by the boot loader and will ignore above physical
1404 In normal kdump cases one does not have to set/change this option
1405 as now bzImage can be compiled as a completely relocatable image
1406 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1407 address. This option is mainly useful for the folks who don't want
1408 to use a bzImage for capturing the crash dump and want to use a
1409 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1410 to be specifically compiled to run from a specific memory area
1411 (normally a reserved region) and this option comes handy.
1413 So if you are using bzImage for capturing the crash dump, leave
1414 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1415 Otherwise if you plan to use vmlinux for capturing the crash dump
1416 change this value to start of the reserved region (Typically 16MB
1417 0x1000000). In other words, it can be set based on the "X" value as
1418 specified in the "crashkernel=YM@XM" command line boot parameter
1419 passed to the panic-ed kernel. Typically this parameter is set as
1420 crashkernel=64M@16M. Please take a look at
1421 Documentation/kdump/kdump.txt for more details about crash dumps.
1423 Usage of bzImage for capturing the crash dump is recommended as
1424 one does not have to build two kernels. Same kernel can be used
1425 as production kernel and capture kernel. Above option should have
1426 gone away after relocatable bzImage support is introduced. But it
1427 is present because there are users out there who continue to use
1428 vmlinux for dump capture. This option should go away down the
1431 Don't change this unless you know what you are doing.
1434 bool "Build a relocatable kernel (EXPERIMENTAL)"
1435 depends on EXPERIMENTAL
1437 This builds a kernel image that retains relocation information
1438 so it can be loaded someplace besides the default 1MB.
1439 The relocations tend to make the kernel binary about 10% larger,
1440 but are discarded at runtime.
1442 One use is for the kexec on panic case where the recovery kernel
1443 must live at a different physical address than the primary
1446 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1447 it has been loaded at and the compile time physical address
1448 (CONFIG_PHYSICAL_START) is ignored.
1450 config PHYSICAL_ALIGN
1452 prompt "Alignment value to which kernel should be aligned" if X86_32
1453 default "0x100000" if X86_32
1454 default "0x200000" if X86_64
1455 range 0x2000 0x400000
1457 This value puts the alignment restrictions on physical address
1458 where kernel is loaded and run from. Kernel is compiled for an
1459 address which meets above alignment restriction.
1461 If bootloader loads the kernel at a non-aligned address and
1462 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1463 address aligned to above value and run from there.
1465 If bootloader loads the kernel at a non-aligned address and
1466 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1467 load address and decompress itself to the address it has been
1468 compiled for and run from there. The address for which kernel is
1469 compiled already meets above alignment restrictions. Hence the
1470 end result is that kernel runs from a physical address meeting
1471 above alignment restrictions.
1473 Don't change this unless you know what you are doing.
1476 bool "Support for hot-pluggable CPUs"
1477 depends on SMP && HOTPLUG
1479 Say Y here to allow turning CPUs off and on. CPUs can be
1480 controlled through /sys/devices/system/cpu.
1481 ( Note: power management support will enable this option
1482 automatically on SMP systems. )
1483 Say N if you want to disable CPU hotplug.
1487 prompt "Compat VDSO support"
1488 depends on X86_32 || IA32_EMULATION
1490 Map the 32-bit VDSO to the predictable old-style address too.
1492 Say N here if you are running a sufficiently recent glibc
1493 version (2.3.3 or later), to remove the high-mapped
1494 VDSO mapping and to exclusively use the randomized VDSO.
1499 bool "Built-in kernel command line"
1502 Allow for specifying boot arguments to the kernel at
1503 build time. On some systems (e.g. embedded ones), it is
1504 necessary or convenient to provide some or all of the
1505 kernel boot arguments with the kernel itself (that is,
1506 to not rely on the boot loader to provide them.)
1508 To compile command line arguments into the kernel,
1509 set this option to 'Y', then fill in the
1510 the boot arguments in CONFIG_CMDLINE.
1512 Systems with fully functional boot loaders (i.e. non-embedded)
1513 should leave this option set to 'N'.
1516 string "Built-in kernel command string"
1517 depends on CMDLINE_BOOL
1520 Enter arguments here that should be compiled into the kernel
1521 image and used at boot time. If the boot loader provides a
1522 command line at boot time, it is appended to this string to
1523 form the full kernel command line, when the system boots.
1525 However, you can use the CONFIG_CMDLINE_OVERRIDE option to
1526 change this behavior.
1528 In most cases, the command line (whether built-in or provided
1529 by the boot loader) should specify the device for the root
1532 config CMDLINE_OVERRIDE
1533 bool "Built-in command line overrides boot loader arguments"
1535 depends on CMDLINE_BOOL
1537 Set this option to 'Y' to have the kernel ignore the boot loader
1538 command line, and use ONLY the built-in command line.
1540 This is used to work around broken boot loaders. This should
1541 be set to 'N' under normal conditions.
1545 config ARCH_ENABLE_MEMORY_HOTPLUG
1547 depends on X86_64 || (X86_32 && HIGHMEM)
1549 config ARCH_ENABLE_MEMORY_HOTREMOVE
1551 depends on MEMORY_HOTPLUG
1553 config HAVE_ARCH_EARLY_PFN_TO_NID
1557 menu "Power management and ACPI options"
1559 config ARCH_HIBERNATION_HEADER
1561 depends on X86_64 && HIBERNATION
1563 source "kernel/power/Kconfig"
1565 source "drivers/acpi/Kconfig"
1570 depends on APM || APM_MODULE
1573 tristate "APM (Advanced Power Management) BIOS support"
1574 depends on X86_32 && PM_SLEEP
1576 APM is a BIOS specification for saving power using several different
1577 techniques. This is mostly useful for battery powered laptops with
1578 APM compliant BIOSes. If you say Y here, the system time will be
1579 reset after a RESUME operation, the /proc/apm device will provide
1580 battery status information, and user-space programs will receive
1581 notification of APM "events" (e.g. battery status change).
1583 If you select "Y" here, you can disable actual use of the APM
1584 BIOS by passing the "apm=off" option to the kernel at boot time.
1586 Note that the APM support is almost completely disabled for
1587 machines with more than one CPU.
1589 In order to use APM, you will need supporting software. For location
1590 and more information, read <file:Documentation/power/pm.txt> and the
1591 Battery Powered Linux mini-HOWTO, available from
1592 <http://www.tldp.org/docs.html#howto>.
1594 This driver does not spin down disk drives (see the hdparm(8)
1595 manpage ("man 8 hdparm") for that), and it doesn't turn off
1596 VESA-compliant "green" monitors.
1598 This driver does not support the TI 4000M TravelMate and the ACER
1599 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1600 desktop machines also don't have compliant BIOSes, and this driver
1601 may cause those machines to panic during the boot phase.
1603 Generally, if you don't have a battery in your machine, there isn't
1604 much point in using this driver and you should say N. If you get
1605 random kernel OOPSes or reboots that don't seem to be related to
1606 anything, try disabling/enabling this option (or disabling/enabling
1609 Some other things you should try when experiencing seemingly random,
1612 1) make sure that you have enough swap space and that it is
1614 2) pass the "no-hlt" option to the kernel
1615 3) switch on floating point emulation in the kernel and pass
1616 the "no387" option to the kernel
1617 4) pass the "floppy=nodma" option to the kernel
1618 5) pass the "mem=4M" option to the kernel (thereby disabling
1619 all but the first 4 MB of RAM)
1620 6) make sure that the CPU is not over clocked.
1621 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1622 8) disable the cache from your BIOS settings
1623 9) install a fan for the video card or exchange video RAM
1624 10) install a better fan for the CPU
1625 11) exchange RAM chips
1626 12) exchange the motherboard.
1628 To compile this driver as a module, choose M here: the
1629 module will be called apm.
1633 config APM_IGNORE_USER_SUSPEND
1634 bool "Ignore USER SUSPEND"
1636 This option will ignore USER SUSPEND requests. On machines with a
1637 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1638 series notebooks, it is necessary to say Y because of a BIOS bug.
1640 config APM_DO_ENABLE
1641 bool "Enable PM at boot time"
1643 Enable APM features at boot time. From page 36 of the APM BIOS
1644 specification: "When disabled, the APM BIOS does not automatically
1645 power manage devices, enter the Standby State, enter the Suspend
1646 State, or take power saving steps in response to CPU Idle calls."
1647 This driver will make CPU Idle calls when Linux is idle (unless this
1648 feature is turned off -- see "Do CPU IDLE calls", below). This
1649 should always save battery power, but more complicated APM features
1650 will be dependent on your BIOS implementation. You may need to turn
1651 this option off if your computer hangs at boot time when using APM
1652 support, or if it beeps continuously instead of suspending. Turn
1653 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1654 T400CDT. This is off by default since most machines do fine without
1658 bool "Make CPU Idle calls when idle"
1660 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1661 On some machines, this can activate improved power savings, such as
1662 a slowed CPU clock rate, when the machine is idle. These idle calls
1663 are made after the idle loop has run for some length of time (e.g.,
1664 333 mS). On some machines, this will cause a hang at boot time or
1665 whenever the CPU becomes idle. (On machines with more than one CPU,
1666 this option does nothing.)
1668 config APM_DISPLAY_BLANK
1669 bool "Enable console blanking using APM"
1671 Enable console blanking using the APM. Some laptops can use this to
1672 turn off the LCD backlight when the screen blanker of the Linux
1673 virtual console blanks the screen. Note that this is only used by
1674 the virtual console screen blanker, and won't turn off the backlight
1675 when using the X Window system. This also doesn't have anything to
1676 do with your VESA-compliant power-saving monitor. Further, this
1677 option doesn't work for all laptops -- it might not turn off your
1678 backlight at all, or it might print a lot of errors to the console,
1679 especially if you are using gpm.
1681 config APM_ALLOW_INTS
1682 bool "Allow interrupts during APM BIOS calls"
1684 Normally we disable external interrupts while we are making calls to
1685 the APM BIOS as a measure to lessen the effects of a badly behaving
1686 BIOS implementation. The BIOS should reenable interrupts if it
1687 needs to. Unfortunately, some BIOSes do not -- especially those in
1688 many of the newer IBM Thinkpads. If you experience hangs when you
1689 suspend, try setting this to Y. Otherwise, say N.
1693 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1695 source "drivers/cpuidle/Kconfig"
1697 source "drivers/idle/Kconfig"
1702 menu "Bus options (PCI etc.)"
1707 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1709 Find out whether you have a PCI motherboard. PCI is the name of a
1710 bus system, i.e. the way the CPU talks to the other stuff inside
1711 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1712 VESA. If you have PCI, say Y, otherwise N.
1715 prompt "PCI access mode"
1716 depends on X86_32 && PCI
1719 On PCI systems, the BIOS can be used to detect the PCI devices and
1720 determine their configuration. However, some old PCI motherboards
1721 have BIOS bugs and may crash if this is done. Also, some embedded
1722 PCI-based systems don't have any BIOS at all. Linux can also try to
1723 detect the PCI hardware directly without using the BIOS.
1725 With this option, you can specify how Linux should detect the
1726 PCI devices. If you choose "BIOS", the BIOS will be used,
1727 if you choose "Direct", the BIOS won't be used, and if you
1728 choose "MMConfig", then PCI Express MMCONFIG will be used.
1729 If you choose "Any", the kernel will try MMCONFIG, then the
1730 direct access method and falls back to the BIOS if that doesn't
1731 work. If unsure, go with the default, which is "Any".
1736 config PCI_GOMMCONFIG
1753 depends on X86_32 && PCI && (PCI_GOBIOS || PCI_GOANY)
1755 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1758 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY || PCI_GOOLPC))
1762 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1766 depends on PCI && OLPC && (PCI_GOOLPC || PCI_GOANY)
1773 bool "Support mmconfig PCI config space access"
1774 depends on X86_64 && PCI && ACPI
1777 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1778 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1780 DMA remapping (DMAR) devices support enables independent address
1781 translations for Direct Memory Access (DMA) from devices.
1782 These DMA remapping devices are reported via ACPI tables
1783 and include PCI device scope covered by these DMA
1786 config DMAR_DEFAULT_ON
1788 prompt "Enable DMA Remapping Devices by default"
1791 Selecting this option will enable a DMAR device at boot time if
1792 one is found. If this option is not selected, DMAR support can
1793 be enabled by passing intel_iommu=on to the kernel. It is
1794 recommended you say N here while the DMAR code remains
1799 prompt "Support for Graphics workaround"
1802 Current Graphics drivers tend to use physical address
1803 for DMA and avoid using DMA APIs. Setting this config
1804 option permits the IOMMU driver to set a unity map for
1805 all the OS-visible memory. Hence the driver can continue
1806 to use physical addresses for DMA.
1808 config DMAR_FLOPPY_WA
1812 Floppy disk drivers are know to bypass DMA API calls
1813 thereby failing to work when IOMMU is enabled. This
1814 workaround will setup a 1:1 mapping for the first
1815 16M to make floppy (an ISA device) work.
1818 bool "Support for Interrupt Remapping (EXPERIMENTAL)"
1819 depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI && EXPERIMENTAL
1821 Supports Interrupt remapping for IO-APIC and MSI devices.
1822 To use x2apic mode in the CPU's which support x2APIC enhancements or
1823 to support platforms with CPU's having > 8 bit APIC ID, say Y.
1825 source "drivers/pci/pcie/Kconfig"
1827 source "drivers/pci/Kconfig"
1829 # x86_64 have no ISA slots, but do have ISA-style DMA.
1838 Find out whether you have ISA slots on your motherboard. ISA is the
1839 name of a bus system, i.e. the way the CPU talks to the other stuff
1840 inside your box. Other bus systems are PCI, EISA, MicroChannel
1841 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1842 newer boards don't support it. If you have ISA, say Y, otherwise N.
1848 The Extended Industry Standard Architecture (EISA) bus was
1849 developed as an open alternative to the IBM MicroChannel bus.
1851 The EISA bus provided some of the features of the IBM MicroChannel
1852 bus while maintaining backward compatibility with cards made for
1853 the older ISA bus. The EISA bus saw limited use between 1988 and
1854 1995 when it was made obsolete by the PCI bus.
1856 Say Y here if you are building a kernel for an EISA-based machine.
1860 source "drivers/eisa/Kconfig"
1865 MicroChannel Architecture is found in some IBM PS/2 machines and
1866 laptops. It is a bus system similar to PCI or ISA. See
1867 <file:Documentation/mca.txt> (and especially the web page given
1868 there) before attempting to build an MCA bus kernel.
1870 source "drivers/mca/Kconfig"
1873 tristate "NatSemi SCx200 support"
1875 This provides basic support for National Semiconductor's
1876 (now AMD's) Geode processors. The driver probes for the
1877 PCI-IDs of several on-chip devices, so its a good dependency
1878 for other scx200_* drivers.
1880 If compiled as a module, the driver is named scx200.
1882 config SCx200HR_TIMER
1883 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1884 depends on SCx200 && GENERIC_TIME
1887 This driver provides a clocksource built upon the on-chip
1888 27MHz high-resolution timer. Its also a workaround for
1889 NSC Geode SC-1100's buggy TSC, which loses time when the
1890 processor goes idle (as is done by the scheduler). The
1891 other workaround is idle=poll boot option.
1893 config GEODE_MFGPT_TIMER
1895 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1896 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1898 This driver provides a clock event source based on the MFGPT
1899 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1900 MFGPTs have a better resolution and max interval than the
1901 generic PIT, and are suitable for use as high-res timers.
1904 bool "One Laptop Per Child support"
1907 Add support for detecting the unique features of the OLPC
1914 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1916 source "drivers/pcmcia/Kconfig"
1918 source "drivers/pci/hotplug/Kconfig"
1923 menu "Executable file formats / Emulations"
1925 source "fs/Kconfig.binfmt"
1927 config IA32_EMULATION
1928 bool "IA32 Emulation"
1930 select COMPAT_BINFMT_ELF
1932 Include code to run 32-bit programs under a 64-bit kernel. You should
1933 likely turn this on, unless you're 100% sure that you don't have any
1934 32-bit programs left.
1937 tristate "IA32 a.out support"
1938 depends on IA32_EMULATION
1940 Support old a.out binaries in the 32bit emulation.
1944 depends on IA32_EMULATION
1946 config COMPAT_FOR_U64_ALIGNMENT
1950 config SYSVIPC_COMPAT
1952 depends on COMPAT && SYSVIPC
1957 config HAVE_ATOMIC_IOMAP
1961 source "net/Kconfig"
1963 source "drivers/Kconfig"
1965 source "drivers/firmware/Kconfig"
1969 source "arch/x86/Kconfig.debug"
1971 source "security/Kconfig"
1973 source "crypto/Kconfig"
1975 source "arch/x86/kvm/Kconfig"
1977 source "lib/Kconfig"
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