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
22 config GENERIC_LOCKBREAK
28 config GENERIC_CMOS_UPDATE
31 config CLOCKSOURCE_WATCHDOG
34 config GENERIC_CLOCKEVENTS
37 config GENERIC_CLOCKEVENTS_BROADCAST
39 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
41 config LOCKDEP_SUPPORT
44 config STACKTRACE_SUPPORT
47 config SEMAPHORE_SLEEPERS
62 config GENERIC_ISA_DMA
72 config GENERIC_HWEIGHT
75 config ARCH_MAY_HAVE_PC_FDC
81 config RWSEM_GENERIC_SPINLOCK
84 config RWSEM_XCHGADD_ALGORITHM
87 config ARCH_HAS_ILOG2_U32
90 config ARCH_HAS_ILOG2_U64
93 config GENERIC_CALIBRATE_DELAY
96 config GENERIC_TIME_VSYSCALL
100 config ARCH_SETS_UP_PER_CPU_AREA
103 config ARCH_SUPPORTS_OPROFILE
112 config ARCH_POPULATES_NODE_MAP
119 # Use the generic interrupt handling code in kernel/irq/:
120 config GENERIC_HARDIRQS
124 config GENERIC_IRQ_PROBE
128 config GENERIC_PENDING_IRQ
130 depends on GENERIC_HARDIRQS && SMP
135 depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)
140 depends on X86_32 && SMP
144 depends on X86_64 && SMP
149 depends on (X86_32 && !(X86_VISWS || X86_VOYAGER)) || (X86_64 && !MK8)
152 config X86_BIOS_REBOOT
154 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
157 config X86_TRAMPOLINE
159 depends on X86_SMP || (X86_VOYAGER && SMP)
164 source "init/Kconfig"
166 menu "Processor type and features"
168 source "kernel/time/Kconfig"
171 bool "Symmetric multi-processing support"
173 This enables support for systems with more than one CPU. If you have
174 a system with only one CPU, like most personal computers, say N. If
175 you have a system with more than one CPU, say Y.
177 If you say N here, the kernel will run on single and multiprocessor
178 machines, but will use only one CPU of a multiprocessor machine. If
179 you say Y here, the kernel will run on many, but not all,
180 singleprocessor machines. On a singleprocessor machine, the kernel
181 will run faster if you say N here.
183 Note that if you say Y here and choose architecture "586" or
184 "Pentium" under "Processor family", the kernel will not work on 486
185 architectures. Similarly, multiprocessor kernels for the "PPro"
186 architecture may not work on all Pentium based boards.
188 People using multiprocessor machines who say Y here should also say
189 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
190 Management" code will be disabled if you say Y here.
192 See also the <file:Documentation/smp.txt>,
193 <file:Documentation/i386/IO-APIC.txt>,
194 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
195 <http://www.tldp.org/docs.html#howto>.
197 If you don't know what to do here, say N.
200 prompt "Subarchitecture Type"
206 Choose this option if your computer is a standard PC or compatible.
212 Select this for an AMD Elan processor.
214 Do not use this option for K6/Athlon/Opteron processors!
216 If unsure, choose "PC-compatible" instead.
221 select SMP if !BROKEN
223 Voyager is an MCA-based 32-way capable SMP architecture proprietary
224 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
228 If you do not specifically know you have a Voyager based machine,
229 say N here, otherwise the kernel you build will not be bootable.
232 bool "NUMAQ (IBM/Sequent)"
237 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
238 multiquad box. This changes the way that processors are bootstrapped,
239 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
240 You will need a new lynxer.elf file to flash your firmware with - send
241 email to <Martin.Bligh@us.ibm.com>.
244 bool "Summit/EXA (IBM x440)"
245 depends on X86_32 && SMP
247 This option is needed for IBM systems that use the Summit/EXA chipset.
248 In particular, it is needed for the x440.
250 If you don't have one of these computers, you should say N here.
251 If you want to build a NUMA kernel, you must select ACPI.
254 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
255 depends on X86_32 && SMP
257 This option is needed for the systems that have more than 8 CPUs
258 and if the system is not of any sub-arch type above.
260 If you don't have such a system, you should say N here.
263 bool "SGI 320/540 (Visual Workstation)"
266 The SGI Visual Workstation series is an IA32-based workstation
267 based on SGI systems chips with some legacy PC hardware attached.
269 Say Y here to create a kernel to run on the SGI 320 or 540.
271 A kernel compiled for the Visual Workstation will not run on PCs
272 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
274 config X86_GENERICARCH
275 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
278 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
279 It is intended for a generic binary kernel.
280 If you want a NUMA kernel, select ACPI. We need SRAT for NUMA.
283 bool "Support for Unisys ES7000 IA32 series"
284 depends on X86_32 && SMP
286 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
287 supposed to run on an IA32-based Unisys ES7000 system.
288 Only choose this option if you have such a system, otherwise you
292 bool "Support for ScaleMP vSMP"
293 depends on X86_64 && PCI
295 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
296 supposed to run on these EM64T-based machines. Only choose this option
297 if you have one of these machines.
301 config SCHED_NO_NO_OMIT_FRAME_POINTER
303 prompt "Single-depth WCHAN output"
306 Calculate simpler /proc/<PID>/wchan values. If this option
307 is disabled then wchan values will recurse back to the
308 caller function. This provides more accurate wchan values,
309 at the expense of slightly more scheduling overhead.
311 If in doubt, say "Y".
315 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
317 This changes the kernel so it can modify itself when it is run
318 under a hypervisor, potentially improving performance significantly
319 over full virtualization. However, when run without a hypervisor
320 the kernel is theoretically slower and slightly larger.
322 menuconfig PARAVIRT_GUEST
323 bool "Paravirtualized guest support"
326 Say Y here to get to see options related to running Linux under
327 various hypervisors. This option alone does not add any kernel code.
329 If you say N, all options in this submenu will be skipped and disabled.
333 source "arch/x86/xen/Kconfig"
336 bool "VMI Guest support"
338 depends on !(X86_VISWS || X86_VOYAGER)
340 VMI provides a paravirtualized interface to the VMware ESX server
341 (it could be used by other hypervisors in theory too, but is not
342 at the moment), by linking the kernel to a GPL-ed ROM module
343 provided by the hypervisor.
345 source "arch/x86/lguest/Kconfig"
351 depends on X86_32 && ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)
354 config HAVE_ARCH_PARSE_SRAT
358 config X86_SUMMIT_NUMA
360 depends on X86_32 && NUMA && (X86_SUMMIT || X86_GENERICARCH)
362 config X86_CYCLONE_TIMER
364 depends on X86_32 && X86_SUMMIT || X86_GENERICARCH
366 config ES7000_CLUSTERED_APIC
368 depends on SMP && X86_ES7000 && MPENTIUMIII
370 source "arch/x86/Kconfig.cpu"
374 prompt "HPET Timer Support" if X86_32
376 Use the IA-PC HPET (High Precision Event Timer) to manage
377 time in preference to the PIT and RTC, if a HPET is
379 HPET is the next generation timer replacing legacy 8254s.
380 The HPET provides a stable time base on SMP
381 systems, unlike the TSC, but it is more expensive to access,
382 as it is off-chip. You can find the HPET spec at
383 <http://www.intel.com/hardwaredesign/hpetspec.htm>.
385 You can safely choose Y here. However, HPET will only be
386 activated if the platform and the BIOS support this feature.
387 Otherwise the 8254 will be used for timing services.
389 Choose N to continue using the legacy 8254 timer.
391 config HPET_EMULATE_RTC
393 depends on HPET_TIMER && RTC=y
395 # Mark as embedded because too many people got it wrong.
396 # The code disables itself when not needed.
398 bool "GART IOMMU support" if EMBEDDED
402 depends on X86_64 && PCI
404 Support for full DMA access of devices with 32bit memory access only
405 on systems with more than 3GB. This is usually needed for USB,
406 sound, many IDE/SATA chipsets and some other devices.
407 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
408 based hardware IOMMU and a software bounce buffer based IOMMU used
409 on Intel systems and as fallback.
410 The code is only active when needed (enough memory and limited
411 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
415 bool "IBM Calgary IOMMU support"
417 depends on X86_64 && PCI && EXPERIMENTAL
419 Support for hardware IOMMUs in IBM's xSeries x366 and x460
420 systems. Needed to run systems with more than 3GB of memory
421 properly with 32-bit PCI devices that do not support DAC
422 (Double Address Cycle). Calgary also supports bus level
423 isolation, where all DMAs pass through the IOMMU. This
424 prevents them from going anywhere except their intended
425 destination. This catches hard-to-find kernel bugs and
426 mis-behaving drivers and devices that do not use the DMA-API
427 properly to set up their DMA buffers. The IOMMU can be
428 turned off at boot time with the iommu=off parameter.
429 Normally the kernel will make the right choice by itself.
432 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
434 prompt "Should Calgary be enabled by default?"
435 depends on CALGARY_IOMMU
437 Should Calgary be enabled by default? if you choose 'y', Calgary
438 will be used (if it exists). If you choose 'n', Calgary will not be
439 used even if it exists. If you choose 'n' and would like to use
440 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
443 # need this always selected by IOMMU for the VIA workaround
447 Support for software bounce buffers used on x86-64 systems
448 which don't have a hardware IOMMU (e.g. the current generation
449 of Intel's x86-64 CPUs). Using this PCI devices which can only
450 access 32-bits of memory can be used on systems with more than
451 3 GB of memory. If unsure, say Y.
455 int "Maximum number of CPUs (2-255)"
458 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
461 This allows you to specify the maximum number of CPUs which this
462 kernel will support. The maximum supported value is 255 and the
463 minimum value which makes sense is 2.
465 This is purely to save memory - each supported CPU adds
466 approximately eight kilobytes to the kernel image.
469 bool "SMT (Hyperthreading) scheduler support"
470 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
472 SMT scheduler support improves the CPU scheduler's decision making
473 when dealing with Intel Pentium 4 chips with HyperThreading at a
474 cost of slightly increased overhead in some places. If unsure say
479 prompt "Multi-core scheduler support"
480 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
482 Multi-core scheduler support improves the CPU scheduler's decision
483 making when dealing with multi-core CPU chips at a cost of slightly
484 increased overhead in some places. If unsure say N here.
486 source "kernel/Kconfig.preempt"
489 bool "Local APIC support on uniprocessors"
490 depends on X86_32 && !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
492 A local APIC (Advanced Programmable Interrupt Controller) is an
493 integrated interrupt controller in the CPU. If you have a single-CPU
494 system which has a processor with a local APIC, you can say Y here to
495 enable and use it. If you say Y here even though your machine doesn't
496 have a local APIC, then the kernel will still run with no slowdown at
497 all. The local APIC supports CPU-generated self-interrupts (timer,
498 performance counters), and the NMI watchdog which detects hard
502 bool "IO-APIC support on uniprocessors"
503 depends on X86_UP_APIC
505 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
506 SMP-capable replacement for PC-style interrupt controllers. Most
507 SMP systems and many recent uniprocessor systems have one.
509 If you have a single-CPU system with an IO-APIC, you can say Y here
510 to use it. If you say Y here even though your machine doesn't have
511 an IO-APIC, then the kernel will still run with no slowdown at all.
513 config X86_LOCAL_APIC
515 depends on X86_64 || (X86_32 && (X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH))
519 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH))
521 config X86_VISWS_APIC
523 depends on X86_32 && X86_VISWS
526 bool "Machine Check Exception"
527 depends on !X86_VOYAGER
529 Machine Check Exception support allows the processor to notify the
530 kernel if it detects a problem (e.g. overheating, component failure).
531 The action the kernel takes depends on the severity of the problem,
532 ranging from a warning message on the console, to halting the machine.
533 Your processor must be a Pentium or newer to support this - check the
534 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
535 have a design flaw which leads to false MCE events - hence MCE is
536 disabled on all P5 processors, unless explicitly enabled with "mce"
537 as a boot argument. Similarly, if MCE is built in and creates a
538 problem on some new non-standard machine, you can boot with "nomce"
539 to disable it. MCE support simply ignores non-MCE processors like
540 the 386 and 486, so nearly everyone can say Y here.
544 prompt "Intel MCE features"
545 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
547 Additional support for intel specific MCE features such as
552 prompt "AMD MCE features"
553 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
555 Additional support for AMD specific MCE features such as
556 the DRAM Error Threshold.
558 config X86_MCE_NONFATAL
559 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
560 depends on X86_32 && X86_MCE
562 Enabling this feature starts a timer that triggers every 5 seconds which
563 will look at the machine check registers to see if anything happened.
564 Non-fatal problems automatically get corrected (but still logged).
565 Disable this if you don't want to see these messages.
566 Seeing the messages this option prints out may be indicative of dying
567 or out-of-spec (ie, overclocked) hardware.
568 This option only does something on certain CPUs.
569 (AMD Athlon/Duron and Intel Pentium 4)
571 config X86_MCE_P4THERMAL
572 bool "check for P4 thermal throttling interrupt."
573 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
575 Enabling this feature will cause a message to be printed when the P4
576 enters thermal throttling.
579 bool "Enable VM86 support" if EMBEDDED
583 This option is required by programs like DOSEMU to run 16-bit legacy
584 code on X86 processors. It also may be needed by software like
585 XFree86 to initialize some video cards via BIOS. Disabling this
586 option saves about 6k.
589 tristate "Toshiba Laptop support"
592 This adds a driver to safely access the System Management Mode of
593 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
594 not work on models with a Phoenix BIOS. The System Management Mode
595 is used to set the BIOS and power saving options on Toshiba portables.
597 For information on utilities to make use of this driver see the
598 Toshiba Linux utilities web site at:
599 <http://www.buzzard.org.uk/toshiba/>.
601 Say Y if you intend to run this kernel on a Toshiba portable.
605 tristate "Dell laptop support"
608 This adds a driver to safely access the System Management Mode
609 of the CPU on the Dell Inspiron 8000. The System Management Mode
610 is used to read cpu temperature and cooling fan status and to
611 control the fans on the I8K portables.
613 This driver has been tested only on the Inspiron 8000 but it may
614 also work with other Dell laptops. You can force loading on other
615 models by passing the parameter `force=1' to the module. Use at
618 For information on utilities to make use of this driver see the
619 I8K Linux utilities web site at:
620 <http://people.debian.org/~dz/i8k/>
622 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
625 config X86_REBOOTFIXUPS
627 prompt "Enable X86 board specific fixups for reboot"
628 depends on X86_32 && X86
630 This enables chipset and/or board specific fixups to be done
631 in order to get reboot to work correctly. This is only needed on
632 some combinations of hardware and BIOS. The symptom, for which
633 this config is intended, is when reboot ends with a stalled/hung
636 Currently, the only fixup is for the Geode machines using
637 CS5530A and CS5536 chipsets.
639 Say Y if you want to enable the fixup. Currently, it's safe to
640 enable this option even if you don't need it.
644 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
647 If you say Y here, you will be able to update the microcode on
648 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
649 Pentium III, Pentium 4, Xeon etc. You will obviously need the
650 actual microcode binary data itself which is not shipped with the
653 For latest news and information on obtaining all the required
654 ingredients for this driver, check:
655 <http://www.urbanmyth.org/microcode/>.
657 To compile this driver as a module, choose M here: the
658 module will be called microcode.
660 config MICROCODE_OLD_INTERFACE
665 tristate "/dev/cpu/*/msr - Model-specific register support"
667 This device gives privileged processes access to the x86
668 Model-Specific Registers (MSRs). It is a character device with
669 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
670 MSR accesses are directed to a specific CPU on multi-processor
674 tristate "/dev/cpu/*/cpuid - CPU information support"
676 This device gives processes access to the x86 CPUID instruction to
677 be executed on a specific processor. It is a character device
678 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
682 prompt "High Memory Support"
683 default HIGHMEM4G if !X86_NUMAQ
684 default HIGHMEM64G if X86_NUMAQ
689 depends on !X86_NUMAQ
691 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
692 However, the address space of 32-bit x86 processors is only 4
693 Gigabytes large. That means that, if you have a large amount of
694 physical memory, not all of it can be "permanently mapped" by the
695 kernel. The physical memory that's not permanently mapped is called
698 If you are compiling a kernel which will never run on a machine with
699 more than 1 Gigabyte total physical RAM, answer "off" here (default
700 choice and suitable for most users). This will result in a "3GB/1GB"
701 split: 3GB are mapped so that each process sees a 3GB virtual memory
702 space and the remaining part of the 4GB virtual memory space is used
703 by the kernel to permanently map as much physical memory as
706 If the machine has between 1 and 4 Gigabytes physical RAM, then
709 If more than 4 Gigabytes is used then answer "64GB" here. This
710 selection turns Intel PAE (Physical Address Extension) mode on.
711 PAE implements 3-level paging on IA32 processors. PAE is fully
712 supported by Linux, PAE mode is implemented on all recent Intel
713 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
714 then the kernel will not boot on CPUs that don't support PAE!
716 The actual amount of total physical memory will either be
717 auto detected or can be forced by using a kernel command line option
718 such as "mem=256M". (Try "man bootparam" or see the documentation of
719 your boot loader (lilo or loadlin) about how to pass options to the
720 kernel at boot time.)
722 If unsure, say "off".
726 depends on !X86_NUMAQ
728 Select this if you have a 32-bit processor and between 1 and 4
729 gigabytes of physical RAM.
733 depends on !M386 && !M486
736 Select this if you have a 32-bit processor and more than 4
737 gigabytes of physical RAM.
742 depends on EXPERIMENTAL
743 prompt "Memory split" if EMBEDDED
747 Select the desired split between kernel and user memory.
749 If the address range available to the kernel is less than the
750 physical memory installed, the remaining memory will be available
751 as "high memory". Accessing high memory is a little more costly
752 than low memory, as it needs to be mapped into the kernel first.
753 Note that increasing the kernel address space limits the range
754 available to user programs, making the address space there
755 tighter. Selecting anything other than the default 3G/1G split
756 will also likely make your kernel incompatible with binary-only
759 If you are not absolutely sure what you are doing, leave this
763 bool "3G/1G user/kernel split"
764 config VMSPLIT_3G_OPT
766 bool "3G/1G user/kernel split (for full 1G low memory)"
768 bool "2G/2G user/kernel split"
769 config VMSPLIT_2G_OPT
771 bool "2G/2G user/kernel split (for full 2G low memory)"
773 bool "1G/3G user/kernel split"
778 default 0xB0000000 if VMSPLIT_3G_OPT
779 default 0x80000000 if VMSPLIT_2G
780 default 0x78000000 if VMSPLIT_2G_OPT
781 default 0x40000000 if VMSPLIT_1G
787 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
791 prompt "PAE (Physical Address Extension) Support"
792 depends on X86_32 && !HIGHMEM4G
793 select RESOURCES_64BIT
795 PAE is required for NX support, and furthermore enables
796 larger swapspace support for non-overcommit purposes. It
797 has the cost of more pagetable lookup overhead, and also
798 consumes more pagetable space per process.
800 # Common NUMA Features
802 bool "Numa Memory Allocation and Scheduler Support (EXPERIMENTAL)"
804 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT || X86_GENERICARCH) && ACPI) && EXPERIMENTAL)
806 default y if (X86_NUMAQ || X86_SUMMIT)
808 Enable NUMA (Non Uniform Memory Access) support.
809 The kernel will try to allocate memory used by a CPU on the
810 local memory controller of the CPU and add some more
811 NUMA awareness to the kernel.
813 For i386 this is currently highly experimental and should be only
814 used for kernel development. It might also cause boot failures.
815 For x86_64 this is recommended on all multiprocessor Opteron systems.
816 If the system is EM64T, you should say N unless your system is
819 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
820 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
824 prompt "Old style AMD Opteron NUMA detection"
825 depends on X86_64 && NUMA && PCI
827 Enable K8 NUMA node topology detection. You should say Y here if
828 you have a multi processor AMD K8 system. This uses an old
829 method to read the NUMA configuration directly from the builtin
830 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
831 instead, which also takes priority if both are compiled in.
833 config X86_64_ACPI_NUMA
835 prompt "ACPI NUMA detection"
836 depends on X86_64 && NUMA && ACPI && PCI
839 Enable ACPI SRAT based node topology detection.
842 bool "NUMA emulation"
843 depends on X86_64 && NUMA
845 Enable NUMA emulation. A flat machine will be split
846 into virtual nodes when booted with "numa=fake=N", where N is the
847 number of nodes. This is only useful for debugging.
851 default "6" if X86_64
852 default "4" if X86_NUMAQ
854 depends on NEED_MULTIPLE_NODES
856 config HAVE_ARCH_BOOTMEM_NODE
858 depends on X86_32 && NUMA
860 config ARCH_HAVE_MEMORY_PRESENT
862 depends on X86_32 && DISCONTIGMEM
864 config NEED_NODE_MEMMAP_SIZE
866 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
868 config HAVE_ARCH_ALLOC_REMAP
870 depends on X86_32 && NUMA
872 config ARCH_FLATMEM_ENABLE
874 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && X86_PC
876 config ARCH_DISCONTIGMEM_ENABLE
878 depends on NUMA && X86_32
880 config ARCH_DISCONTIGMEM_DEFAULT
882 depends on NUMA && X86_32
884 config ARCH_SPARSEMEM_DEFAULT
888 config ARCH_SPARSEMEM_ENABLE
890 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC)
891 select SPARSEMEM_STATIC if X86_32
892 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
894 config ARCH_SELECT_MEMORY_MODEL
896 depends on ARCH_SPARSEMEM_ENABLE
898 config ARCH_MEMORY_PROBE
900 depends on MEMORY_HOTPLUG
905 bool "Allocate 3rd-level pagetables from highmem"
906 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
908 The VM uses one page table entry for each page of physical memory.
909 For systems with a lot of RAM, this can be wasteful of precious
910 low memory. Setting this option will put user-space page table
911 entries in high memory.
913 config MATH_EMULATION
915 prompt "Math emulation" if X86_32
917 Linux can emulate a math coprocessor (used for floating point
918 operations) if you don't have one. 486DX and Pentium processors have
919 a math coprocessor built in, 486SX and 386 do not, unless you added
920 a 487DX or 387, respectively. (The messages during boot time can
921 give you some hints here ["man dmesg"].) Everyone needs either a
922 coprocessor or this emulation.
924 If you don't have a math coprocessor, you need to say Y here; if you
925 say Y here even though you have a coprocessor, the coprocessor will
926 be used nevertheless. (This behavior can be changed with the kernel
927 command line option "no387", which comes handy if your coprocessor
928 is broken. Try "man bootparam" or see the documentation of your boot
929 loader (lilo or loadlin) about how to pass options to the kernel at
930 boot time.) This means that it is a good idea to say Y here if you
931 intend to use this kernel on different machines.
933 More information about the internals of the Linux math coprocessor
934 emulation can be found in <file:arch/x86/math-emu/README>.
936 If you are not sure, say Y; apart from resulting in a 66 KB bigger
937 kernel, it won't hurt.
940 bool "MTRR (Memory Type Range Register) support"
942 On Intel P6 family processors (Pentium Pro, Pentium II and later)
943 the Memory Type Range Registers (MTRRs) may be used to control
944 processor access to memory ranges. This is most useful if you have
945 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
946 allows bus write transfers to be combined into a larger transfer
947 before bursting over the PCI/AGP bus. This can increase performance
948 of image write operations 2.5 times or more. Saying Y here creates a
949 /proc/mtrr file which may be used to manipulate your processor's
950 MTRRs. Typically the X server should use this.
952 This code has a reasonably generic interface so that similar
953 control registers on other processors can be easily supported
956 The Cyrix 6x86, 6x86MX and M II processors have Address Range
957 Registers (ARRs) which provide a similar functionality to MTRRs. For
958 these, the ARRs are used to emulate the MTRRs.
959 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
960 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
961 write-combining. All of these processors are supported by this code
962 and it makes sense to say Y here if you have one of them.
964 Saying Y here also fixes a problem with buggy SMP BIOSes which only
965 set the MTRRs for the boot CPU and not for the secondary CPUs. This
966 can lead to all sorts of problems, so it's good to say Y here.
968 You can safely say Y even if your machine doesn't have MTRRs, you'll
969 just add about 9 KB to your kernel.
971 See <file:Documentation/mtrr.txt> for more information.
975 prompt "EFI runtime service support"
978 This enables the kernel to use EFI runtime services that are
979 available (such as the EFI variable services).
981 This option is only useful on systems that have EFI firmware.
982 In addition, you should use the latest ELILO loader available
983 at <http://elilo.sourceforge.net> in order to take advantage
984 of EFI runtime services. However, even with this option, the
985 resultant kernel should continue to boot on existing non-EFI
990 prompt "Enable kernel irq balancing"
991 depends on X86_32 && SMP && X86_IO_APIC
993 The default yes will allow the kernel to do irq load balancing.
994 Saying no will keep the kernel from doing irq load balancing.
996 # turning this on wastes a bunch of space.
997 # Summit needs it only when NUMA is on
1000 depends on X86_32 && (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
1004 prompt "Enable seccomp to safely compute untrusted bytecode"
1007 This kernel feature is useful for number crunching applications
1008 that may need to compute untrusted bytecode during their
1009 execution. By using pipes or other transports made available to
1010 the process as file descriptors supporting the read/write
1011 syscalls, it's possible to isolate those applications in
1012 their own address space using seccomp. Once seccomp is
1013 enabled via /proc/<pid>/seccomp, it cannot be disabled
1014 and the task is only allowed to execute a few safe syscalls
1015 defined by each seccomp mode.
1017 If unsure, say Y. Only embedded should say N here.
1019 config CC_STACKPROTECTOR
1020 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1021 depends on X86_64 && EXPERIMENTAL
1023 This option turns on the -fstack-protector GCC feature. This
1024 feature puts, at the beginning of critical functions, a canary
1025 value on the stack just before the return address, and validates
1026 the value just before actually returning. Stack based buffer
1027 overflows (that need to overwrite this return address) now also
1028 overwrite the canary, which gets detected and the attack is then
1029 neutralized via a kernel panic.
1031 This feature requires gcc version 4.2 or above, or a distribution
1032 gcc with the feature backported. Older versions are automatically
1033 detected and for those versions, this configuration option is ignored.
1035 config CC_STACKPROTECTOR_ALL
1036 bool "Use stack-protector for all functions"
1037 depends on CC_STACKPROTECTOR
1039 Normally, GCC only inserts the canary value protection for
1040 functions that use large-ish on-stack buffers. By enabling
1041 this option, GCC will be asked to do this for ALL functions.
1043 source kernel/Kconfig.hz
1046 bool "kexec system call"
1048 kexec is a system call that implements the ability to shutdown your
1049 current kernel, and to start another kernel. It is like a reboot
1050 but it is independent of the system firmware. And like a reboot
1051 you can start any kernel with it, not just Linux.
1053 The name comes from the similarity to the exec system call.
1055 It is an ongoing process to be certain the hardware in a machine
1056 is properly shutdown, so do not be surprised if this code does not
1057 initially work for you. It may help to enable device hotplugging
1058 support. As of this writing the exact hardware interface is
1059 strongly in flux, so no good recommendation can be made.
1062 bool "kernel crash dumps (EXPERIMENTAL)"
1063 depends on EXPERIMENTAL
1064 depends on X86_64 || (X86_32 && HIGHMEM)
1066 Generate crash dump after being started by kexec.
1067 This should be normally only set in special crash dump kernels
1068 which are loaded in the main kernel with kexec-tools into
1069 a specially reserved region and then later executed after
1070 a crash by kdump/kexec. The crash dump kernel must be compiled
1071 to a memory address not used by the main kernel or BIOS using
1072 PHYSICAL_START, or it must be built as a relocatable image
1073 (CONFIG_RELOCATABLE=y).
1074 For more details see Documentation/kdump/kdump.txt
1076 config PHYSICAL_START
1077 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1078 default "0x1000000" if X86_NUMAQ
1079 default "0x200000" if X86_64
1082 This gives the physical address where the kernel is loaded.
1084 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1085 bzImage will decompress itself to above physical address and
1086 run from there. Otherwise, bzImage will run from the address where
1087 it has been loaded by the boot loader and will ignore above physical
1090 In normal kdump cases one does not have to set/change this option
1091 as now bzImage can be compiled as a completely relocatable image
1092 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1093 address. This option is mainly useful for the folks who don't want
1094 to use a bzImage for capturing the crash dump and want to use a
1095 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1096 to be specifically compiled to run from a specific memory area
1097 (normally a reserved region) and this option comes handy.
1099 So if you are using bzImage for capturing the crash dump, leave
1100 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1101 Otherwise if you plan to use vmlinux for capturing the crash dump
1102 change this value to start of the reserved region (Typically 16MB
1103 0x1000000). In other words, it can be set based on the "X" value as
1104 specified in the "crashkernel=YM@XM" command line boot parameter
1105 passed to the panic-ed kernel. Typically this parameter is set as
1106 crashkernel=64M@16M. Please take a look at
1107 Documentation/kdump/kdump.txt for more details about crash dumps.
1109 Usage of bzImage for capturing the crash dump is recommended as
1110 one does not have to build two kernels. Same kernel can be used
1111 as production kernel and capture kernel. Above option should have
1112 gone away after relocatable bzImage support is introduced. But it
1113 is present because there are users out there who continue to use
1114 vmlinux for dump capture. This option should go away down the
1117 Don't change this unless you know what you are doing.
1120 bool "Build a relocatable kernel (EXPERIMENTAL)"
1121 depends on EXPERIMENTAL
1123 This builds a kernel image that retains relocation information
1124 so it can be loaded someplace besides the default 1MB.
1125 The relocations tend to make the kernel binary about 10% larger,
1126 but are discarded at runtime.
1128 One use is for the kexec on panic case where the recovery kernel
1129 must live at a different physical address than the primary
1132 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1133 it has been loaded at and the compile time physical address
1134 (CONFIG_PHYSICAL_START) is ignored.
1136 config PHYSICAL_ALIGN
1138 prompt "Alignment value to which kernel should be aligned" if X86_32
1139 default "0x100000" if X86_32
1140 default "0x200000" if X86_64
1141 range 0x2000 0x400000
1143 This value puts the alignment restrictions on physical address
1144 where kernel is loaded and run from. Kernel is compiled for an
1145 address which meets above alignment restriction.
1147 If bootloader loads the kernel at a non-aligned address and
1148 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1149 address aligned to above value and run from there.
1151 If bootloader loads the kernel at a non-aligned address and
1152 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1153 load address and decompress itself to the address it has been
1154 compiled for and run from there. The address for which kernel is
1155 compiled already meets above alignment restrictions. Hence the
1156 end result is that kernel runs from a physical address meeting
1157 above alignment restrictions.
1159 Don't change this unless you know what you are doing.
1162 bool "Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL)"
1163 depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
1165 Say Y here to experiment with turning CPUs off and on, and to
1166 enable suspend on SMP systems. CPUs can be controlled through
1167 /sys/devices/system/cpu.
1168 Say N if you want to disable CPU hotplug and don't need to
1173 prompt "Compat VDSO support"
1174 depends on X86_32 || IA32_EMULATION
1176 Map the 32-bit VDSO to the predictable old-style address too.
1178 Say N here if you are running a sufficiently recent glibc
1179 version (2.3.3 or later), to remove the high-mapped
1180 VDSO mapping and to exclusively use the randomized VDSO.
1186 config ARCH_ENABLE_MEMORY_HOTPLUG
1188 depends on X86_64 || (X86_32 && HIGHMEM)
1190 config HAVE_ARCH_EARLY_PFN_TO_NID
1194 menu "Power management options"
1195 depends on !X86_VOYAGER
1197 config ARCH_HIBERNATION_HEADER
1199 depends on X86_64 && HIBERNATION
1201 source "kernel/power/Kconfig"
1203 source "drivers/acpi/Kconfig"
1208 depends on APM || APM_MODULE
1211 tristate "APM (Advanced Power Management) BIOS support"
1212 depends on X86_32 && PM_SLEEP && !X86_VISWS
1214 APM is a BIOS specification for saving power using several different
1215 techniques. This is mostly useful for battery powered laptops with
1216 APM compliant BIOSes. If you say Y here, the system time will be
1217 reset after a RESUME operation, the /proc/apm device will provide
1218 battery status information, and user-space programs will receive
1219 notification of APM "events" (e.g. battery status change).
1221 If you select "Y" here, you can disable actual use of the APM
1222 BIOS by passing the "apm=off" option to the kernel at boot time.
1224 Note that the APM support is almost completely disabled for
1225 machines with more than one CPU.
1227 In order to use APM, you will need supporting software. For location
1228 and more information, read <file:Documentation/pm.txt> and the
1229 Battery Powered Linux mini-HOWTO, available from
1230 <http://www.tldp.org/docs.html#howto>.
1232 This driver does not spin down disk drives (see the hdparm(8)
1233 manpage ("man 8 hdparm") for that), and it doesn't turn off
1234 VESA-compliant "green" monitors.
1236 This driver does not support the TI 4000M TravelMate and the ACER
1237 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1238 desktop machines also don't have compliant BIOSes, and this driver
1239 may cause those machines to panic during the boot phase.
1241 Generally, if you don't have a battery in your machine, there isn't
1242 much point in using this driver and you should say N. If you get
1243 random kernel OOPSes or reboots that don't seem to be related to
1244 anything, try disabling/enabling this option (or disabling/enabling
1247 Some other things you should try when experiencing seemingly random,
1250 1) make sure that you have enough swap space and that it is
1252 2) pass the "no-hlt" option to the kernel
1253 3) switch on floating point emulation in the kernel and pass
1254 the "no387" option to the kernel
1255 4) pass the "floppy=nodma" option to the kernel
1256 5) pass the "mem=4M" option to the kernel (thereby disabling
1257 all but the first 4 MB of RAM)
1258 6) make sure that the CPU is not over clocked.
1259 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1260 8) disable the cache from your BIOS settings
1261 9) install a fan for the video card or exchange video RAM
1262 10) install a better fan for the CPU
1263 11) exchange RAM chips
1264 12) exchange the motherboard.
1266 To compile this driver as a module, choose M here: the
1267 module will be called apm.
1271 config APM_IGNORE_USER_SUSPEND
1272 bool "Ignore USER SUSPEND"
1274 This option will ignore USER SUSPEND requests. On machines with a
1275 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1276 series notebooks, it is necessary to say Y because of a BIOS bug.
1278 config APM_DO_ENABLE
1279 bool "Enable PM at boot time"
1281 Enable APM features at boot time. From page 36 of the APM BIOS
1282 specification: "When disabled, the APM BIOS does not automatically
1283 power manage devices, enter the Standby State, enter the Suspend
1284 State, or take power saving steps in response to CPU Idle calls."
1285 This driver will make CPU Idle calls when Linux is idle (unless this
1286 feature is turned off -- see "Do CPU IDLE calls", below). This
1287 should always save battery power, but more complicated APM features
1288 will be dependent on your BIOS implementation. You may need to turn
1289 this option off if your computer hangs at boot time when using APM
1290 support, or if it beeps continuously instead of suspending. Turn
1291 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1292 T400CDT. This is off by default since most machines do fine without
1296 bool "Make CPU Idle calls when idle"
1298 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1299 On some machines, this can activate improved power savings, such as
1300 a slowed CPU clock rate, when the machine is idle. These idle calls
1301 are made after the idle loop has run for some length of time (e.g.,
1302 333 mS). On some machines, this will cause a hang at boot time or
1303 whenever the CPU becomes idle. (On machines with more than one CPU,
1304 this option does nothing.)
1306 config APM_DISPLAY_BLANK
1307 bool "Enable console blanking using APM"
1309 Enable console blanking using the APM. Some laptops can use this to
1310 turn off the LCD backlight when the screen blanker of the Linux
1311 virtual console blanks the screen. Note that this is only used by
1312 the virtual console screen blanker, and won't turn off the backlight
1313 when using the X Window system. This also doesn't have anything to
1314 do with your VESA-compliant power-saving monitor. Further, this
1315 option doesn't work for all laptops -- it might not turn off your
1316 backlight at all, or it might print a lot of errors to the console,
1317 especially if you are using gpm.
1319 config APM_ALLOW_INTS
1320 bool "Allow interrupts during APM BIOS calls"
1322 Normally we disable external interrupts while we are making calls to
1323 the APM BIOS as a measure to lessen the effects of a badly behaving
1324 BIOS implementation. The BIOS should reenable interrupts if it
1325 needs to. Unfortunately, some BIOSes do not -- especially those in
1326 many of the newer IBM Thinkpads. If you experience hangs when you
1327 suspend, try setting this to Y. Otherwise, say N.
1329 config APM_REAL_MODE_POWER_OFF
1330 bool "Use real mode APM BIOS call to power off"
1332 Use real mode APM BIOS calls to switch off the computer. This is
1333 a work-around for a number of buggy BIOSes. Switch this option on if
1334 your computer crashes instead of powering off properly.
1338 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1340 source "drivers/cpuidle/Kconfig"
1345 menu "Bus options (PCI etc.)"
1348 bool "PCI support" if !X86_VISWS
1349 depends on !X86_VOYAGER
1351 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1353 Find out whether you have a PCI motherboard. PCI is the name of a
1354 bus system, i.e. the way the CPU talks to the other stuff inside
1355 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1356 VESA. If you have PCI, say Y, otherwise N.
1358 The PCI-HOWTO, available from
1359 <http://www.tldp.org/docs.html#howto>, contains valuable
1360 information about which PCI hardware does work under Linux and which
1364 prompt "PCI access mode"
1365 depends on X86_32 && PCI && !X86_VISWS
1368 On PCI systems, the BIOS can be used to detect the PCI devices and
1369 determine their configuration. However, some old PCI motherboards
1370 have BIOS bugs and may crash if this is done. Also, some embedded
1371 PCI-based systems don't have any BIOS at all. Linux can also try to
1372 detect the PCI hardware directly without using the BIOS.
1374 With this option, you can specify how Linux should detect the
1375 PCI devices. If you choose "BIOS", the BIOS will be used,
1376 if you choose "Direct", the BIOS won't be used, and if you
1377 choose "MMConfig", then PCI Express MMCONFIG will be used.
1378 If you choose "Any", the kernel will try MMCONFIG, then the
1379 direct access method and falls back to the BIOS if that doesn't
1380 work. If unsure, go with the default, which is "Any".
1385 config PCI_GOMMCONFIG
1398 depends on X86_32 && !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1400 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1403 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1407 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1414 bool "Support mmconfig PCI config space access"
1415 depends on X86_64 && PCI && ACPI
1418 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1419 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1421 DMA remapping (DMAR) devices support enables independent address
1422 translations for Direct Memory Access (DMA) from devices.
1423 These DMA remapping devices are reported via ACPI tables
1424 and include PCI device scope covered by these DMA
1429 prompt "Support for Graphics workaround"
1432 Current Graphics drivers tend to use physical address
1433 for DMA and avoid using DMA APIs. Setting this config
1434 option permits the IOMMU driver to set a unity map for
1435 all the OS-visible memory. Hence the driver can continue
1436 to use physical addresses for DMA.
1438 config DMAR_FLOPPY_WA
1442 Floppy disk drivers are know to bypass DMA API calls
1443 thereby failing to work when IOMMU is enabled. This
1444 workaround will setup a 1:1 mapping for the first
1445 16M to make floppy (an ISA device) work.
1447 source "drivers/pci/pcie/Kconfig"
1449 source "drivers/pci/Kconfig"
1451 # x86_64 have no ISA slots, but do have ISA-style DMA.
1459 depends on !(X86_VOYAGER || X86_VISWS)
1461 Find out whether you have ISA slots on your motherboard. ISA is the
1462 name of a bus system, i.e. the way the CPU talks to the other stuff
1463 inside your box. Other bus systems are PCI, EISA, MicroChannel
1464 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1465 newer boards don't support it. If you have ISA, say Y, otherwise N.
1471 The Extended Industry Standard Architecture (EISA) bus was
1472 developed as an open alternative to the IBM MicroChannel bus.
1474 The EISA bus provided some of the features of the IBM MicroChannel
1475 bus while maintaining backward compatibility with cards made for
1476 the older ISA bus. The EISA bus saw limited use between 1988 and
1477 1995 when it was made obsolete by the PCI bus.
1479 Say Y here if you are building a kernel for an EISA-based machine.
1483 source "drivers/eisa/Kconfig"
1486 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1487 default y if X86_VOYAGER
1489 MicroChannel Architecture is found in some IBM PS/2 machines and
1490 laptops. It is a bus system similar to PCI or ISA. See
1491 <file:Documentation/mca.txt> (and especially the web page given
1492 there) before attempting to build an MCA bus kernel.
1494 source "drivers/mca/Kconfig"
1497 tristate "NatSemi SCx200 support"
1498 depends on !X86_VOYAGER
1500 This provides basic support for National Semiconductor's
1501 (now AMD's) Geode processors. The driver probes for the
1502 PCI-IDs of several on-chip devices, so its a good dependency
1503 for other scx200_* drivers.
1505 If compiled as a module, the driver is named scx200.
1507 config SCx200HR_TIMER
1508 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1509 depends on SCx200 && GENERIC_TIME
1512 This driver provides a clocksource built upon the on-chip
1513 27MHz high-resolution timer. Its also a workaround for
1514 NSC Geode SC-1100's buggy TSC, which loses time when the
1515 processor goes idle (as is done by the scheduler). The
1516 other workaround is idle=poll boot option.
1518 config GEODE_MFGPT_TIMER
1520 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1521 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1523 This driver provides a clock event source based on the MFGPT
1524 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1525 MFGPTs have a better resolution and max interval than the
1526 generic PIT, and are suitable for use as high-res timers.
1532 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1534 source "drivers/pcmcia/Kconfig"
1536 source "drivers/pci/hotplug/Kconfig"
1541 menu "Executable file formats / Emulations"
1543 source "fs/Kconfig.binfmt"
1545 config IA32_EMULATION
1546 bool "IA32 Emulation"
1548 select COMPAT_BINFMT_ELF
1550 Include code to run 32-bit programs under a 64-bit kernel. You should
1551 likely turn this on, unless you're 100% sure that you don't have any
1552 32-bit programs left.
1555 tristate "IA32 a.out support"
1556 depends on IA32_EMULATION
1558 Support old a.out binaries in the 32bit emulation.
1562 depends on IA32_EMULATION
1564 config COMPAT_FOR_U64_ALIGNMENT
1568 config SYSVIPC_COMPAT
1570 depends on X86_64 && COMPAT && SYSVIPC
1575 source "net/Kconfig"
1577 source "drivers/Kconfig"
1579 source "drivers/firmware/Kconfig"
1583 source "kernel/Kconfig.instrumentation"
1585 source "arch/x86/Kconfig.debug"
1587 source "security/Kconfig"
1589 source "crypto/Kconfig"
1591 source "lib/Kconfig"
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