2 # For a description of the syntax of this configuration file,
3 # see Documentation/kbuild/kconfig-language.txt.
6 mainmenu "Linux Kernel Configuration"
12 This is Linux's home port. Linux was originally native to the Intel
13 386, and runs on all the later x86 processors including the Intel
14 486, 586, Pentiums, and various instruction-set-compatible chips by
15 AMD, Cyrix, and others.
17 config SEMAPHORE_SLEEPERS
32 config GENERIC_ISA_DMA
40 config ARCH_MAY_HAVE_PC_FDC
46 menu "Processor type and features"
49 prompt "Subarchitecture Type"
55 Choose this option if your computer is a standard PC or compatible.
60 Select this for an AMD Elan processor.
62 Do not use this option for K6/Athlon/Opteron processors!
64 If unsure, choose "PC-compatible" instead.
69 Voyager is an MCA-based 32-way capable SMP architecture proprietary
70 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
74 If you do not specifically know you have a Voyager based machine,
75 say N here, otherwise the kernel you build will not be bootable.
78 bool "NUMAQ (IBM/Sequent)"
81 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
82 multiquad box. This changes the way that processors are bootstrapped,
83 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
84 You will need a new lynxer.elf file to flash your firmware with - send
85 email to <Martin.Bligh@us.ibm.com>.
88 bool "Summit/EXA (IBM x440)"
91 This option is needed for IBM systems that use the Summit/EXA chipset.
92 In particular, it is needed for the x440.
94 If you don't have one of these computers, you should say N here.
97 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
100 This option is needed for the systems that have more than 8 CPUs
101 and if the system is not of any sub-arch type above.
103 If you don't have such a system, you should say N here.
106 bool "SGI 320/540 (Visual Workstation)"
108 The SGI Visual Workstation series is an IA32-based workstation
109 based on SGI systems chips with some legacy PC hardware attached.
111 Say Y here to create a kernel to run on the SGI 320 or 540.
113 A kernel compiled for the Visual Workstation will not run on PCs
114 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
116 config X86_GENERICARCH
117 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
120 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
121 It is intended for a generic binary kernel.
124 bool "Support for Unisys ES7000 IA32 series"
127 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
128 supposed to run on an IA32-based Unisys ES7000 system.
129 Only choose this option if you have such a system, otherwise you
137 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
139 config X86_SUMMIT_NUMA
142 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
144 config X86_CYCLONE_TIMER
147 depends on X86_SUMMIT || X86_GENERICARCH
149 config ES7000_CLUSTERED_APIC
152 depends on SMP && X86_ES7000 && MPENTIUMIII
157 prompt "Processor family"
163 This is the processor type of your CPU. This information is used for
164 optimizing purposes. In order to compile a kernel that can run on
165 all x86 CPU types (albeit not optimally fast), you can specify
168 The kernel will not necessarily run on earlier architectures than
169 the one you have chosen, e.g. a Pentium optimized kernel will run on
170 a PPro, but not necessarily on a i486.
172 Here are the settings recommended for greatest speed:
173 - "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI
174 486DLC/DLC2, UMC 486SX-S and NexGen Nx586. Only "386" kernels
175 will run on a 386 class machine.
176 - "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
177 SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
178 - "586" for generic Pentium CPUs lacking the TSC
179 (time stamp counter) register.
180 - "Pentium-Classic" for the Intel Pentium.
181 - "Pentium-MMX" for the Intel Pentium MMX.
182 - "Pentium-Pro" for the Intel Pentium Pro.
183 - "Pentium-II" for the Intel Pentium II or pre-Coppermine Celeron.
184 - "Pentium-III" for the Intel Pentium III or Coppermine Celeron.
185 - "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.
186 - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
187 - "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
188 - "Crusoe" for the Transmeta Crusoe series.
189 - "Efficeon" for the Transmeta Efficeon series.
190 - "Winchip-C6" for original IDT Winchip.
191 - "Winchip-2" for IDT Winchip 2.
192 - "Winchip-2A" for IDT Winchips with 3dNow! capabilities.
193 - "GeodeGX1" for Geode GX1 (Cyrix MediaGX).
194 - "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.
195 - "VIA C3-2 for VIA C3-2 "Nehemiah" (model 9 and above).
197 If you don't know what to do, choose "386".
202 Select this for a 486 series processor, either Intel or one of the
203 compatible processors from AMD, Cyrix, IBM, or Intel. Includes DX,
204 DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or
208 bool "586/K5/5x86/6x86/6x86MX"
210 Select this for an 586 or 686 series processor such as the AMD K5,
211 the Cyrix 5x86, 6x86 and 6x86MX. This choice does not
212 assume the RDTSC (Read Time Stamp Counter) instruction.
215 bool "Pentium-Classic"
217 Select this for a Pentium Classic processor with the RDTSC (Read
218 Time Stamp Counter) instruction for benchmarking.
223 Select this for a Pentium with the MMX graphics/multimedia
224 extended instructions.
229 Select this for Intel Pentium Pro chips. This enables the use of
230 Pentium Pro extended instructions, and disables the init-time guard
231 against the f00f bug found in earlier Pentiums.
234 bool "Pentium-II/Celeron(pre-Coppermine)"
236 Select this for Intel chips based on the Pentium-II and
237 pre-Coppermine Celeron core. This option enables an unaligned
238 copy optimization, compiles the kernel with optimization flags
239 tailored for the chip, and applies any applicable Pentium Pro
243 bool "Pentium-III/Celeron(Coppermine)/Pentium-III Xeon"
245 Select this for Intel chips based on the Pentium-III and
246 Celeron-Coppermine core. This option enables use of some
247 extended prefetch instructions in addition to the Pentium II
253 Select this for Intel Pentium M (not Pentium-4 M)
257 bool "Pentium-4/Celeron(P4-based)/Pentium-4 M/Xeon"
259 Select this for Intel Pentium 4 chips. This includes the
260 Pentium 4, P4-based Celeron and Xeon, and Pentium-4 M
261 (not Pentium M) chips. This option enables compile flags
262 optimized for the chip, uses the correct cache shift, and
263 applies any applicable Pentium III optimizations.
266 bool "K6/K6-II/K6-III"
268 Select this for an AMD K6-family processor. Enables use of
269 some extended instructions, and passes appropriate optimization
273 bool "Athlon/Duron/K7"
275 Select this for an AMD Athlon K7-family processor. Enables use of
276 some extended instructions, and passes appropriate optimization
280 bool "Opteron/Athlon64/Hammer/K8"
282 Select this for an AMD Opteron or Athlon64 Hammer-family processor. Enables
283 use of some extended instructions, and passes appropriate optimization
289 Select this for a Transmeta Crusoe processor. Treats the processor
290 like a 586 with TSC, and sets some GCC optimization flags (like a
291 Pentium Pro with no alignment requirements).
296 Select this for a Transmeta Efficeon processor.
301 Select this for an IDT Winchip C6 chip. Linux and GCC
302 treat this chip as a 586TSC with some extended instructions
303 and alignment requirements.
308 Select this for an IDT Winchip-2. Linux and GCC
309 treat this chip as a 586TSC with some extended instructions
310 and alignment requirements.
313 bool "Winchip-2A/Winchip-3"
315 Select this for an IDT Winchip-2A or 3. Linux and GCC
316 treat this chip as a 586TSC with some extended instructions
317 and alignment reqirements. Also enable out of order memory
318 stores for this CPU, which can increase performance of some
324 Select this for a Geode GX1 (Cyrix MediaGX) chip.
327 bool "CyrixIII/VIA-C3"
329 Select this for a Cyrix III or C3 chip. Presently Linux and GCC
330 treat this chip as a generic 586. Whilst the CPU is 686 class,
331 it lacks the cmov extension which gcc assumes is present when
333 Note that Nehemiah (Model 9) and above will not boot with this
334 kernel due to them lacking the 3DNow! instructions used in earlier
335 incarnations of the CPU.
338 bool "VIA C3-2 (Nehemiah)"
340 Select this for a VIA C3 "Nehemiah". Selecting this enables usage
341 of SSE and tells gcc to treat the CPU as a 686.
342 Note, this kernel will not boot on older (pre model 9) C3s.
347 bool "Generic x86 support"
349 Instead of just including optimizations for the selected
350 x86 variant (e.g. PII, Crusoe or Athlon), include some more
351 generic optimizations as well. This will make the kernel
352 perform better on x86 CPUs other than that selected.
354 This is really intended for distributors who need more
355 generic optimizations.
360 # Define implied options from the CPU selection here
372 config X86_L1_CACHE_SHIFT
374 default "7" if MPENTIUM4 || X86_GENERIC
375 default "4" if X86_ELAN || M486 || M386
376 default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MEFFICEON || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2 || MGEODEGX1
377 default "6" if MK7 || MK8 || MPENTIUMM
379 config RWSEM_GENERIC_SPINLOCK
384 config RWSEM_XCHGADD_ALGORITHM
389 config GENERIC_CALIBRATE_DELAY
393 config X86_PPRO_FENCE
395 depends on M686 || M586MMX || M586TSC || M586 || M486 || M386 || MGEODEGX1
400 depends on M586MMX || M586TSC || M586 || M486 || M386
403 config X86_WP_WORKS_OK
423 config X86_ALIGNMENT_16
425 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
430 depends on MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || MK8 || MEFFICEON
433 config X86_INTEL_USERCOPY
435 depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7 || MEFFICEON
438 config X86_USE_PPRO_CHECKSUM
440 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2 || MEFFICEON
445 depends on MCYRIXIII || MK7
450 depends on (MWINCHIP3D || MWINCHIP2 || MWINCHIPC6) && MTRR
454 bool "HPET Timer Support"
456 This enables the use of the HPET for the kernel's internal timer.
457 HPET is the next generation timer replacing legacy 8254s.
458 You can safely choose Y here. However, HPET will only be
459 activated if the platform and the BIOS support this feature.
460 Otherwise the 8254 will be used for timing services.
462 Choose N to continue using the legacy 8254 timer.
464 config HPET_EMULATE_RTC
466 depends on HPET_TIMER && RTC=y
470 bool "Symmetric multi-processing support"
472 This enables support for systems with more than one CPU. If you have
473 a system with only one CPU, like most personal computers, say N. If
474 you have a system with more than one CPU, say Y.
476 If you say N here, the kernel will run on single and multiprocessor
477 machines, but will use only one CPU of a multiprocessor machine. If
478 you say Y here, the kernel will run on many, but not all,
479 singleprocessor machines. On a singleprocessor machine, the kernel
480 will run faster if you say N here.
482 Note that if you say Y here and choose architecture "586" or
483 "Pentium" under "Processor family", the kernel will not work on 486
484 architectures. Similarly, multiprocessor kernels for the "PPro"
485 architecture may not work on all Pentium based boards.
487 People using multiprocessor machines who say Y here should also say
488 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
489 Management" code will be disabled if you say Y here.
491 See also the <file:Documentation/smp.txt>,
492 <file:Documentation/i386/IO-APIC.txt>,
493 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
494 <http://www.tldp.org/docs.html#howto>.
496 If you don't know what to do here, say N.
499 int "Maximum number of CPUs (2-255)"
502 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
505 This allows you to specify the maximum number of CPUs which this
506 kernel will support. The maximum supported value is 255 and the
507 minimum value which makes sense is 2.
509 This is purely to save memory - each supported CPU adds
510 approximately eight kilobytes to the kernel image.
513 bool "SMT (Hyperthreading) scheduler support"
517 SMT scheduler support improves the CPU scheduler's decision making
518 when dealing with Intel Pentium 4 chips with HyperThreading at a
519 cost of slightly increased overhead in some places. If unsure say
522 source "kernel/Kconfig.preempt"
525 bool "Local APIC support on uniprocessors"
526 depends on !SMP && !(X86_VISWS || X86_VOYAGER)
528 A local APIC (Advanced Programmable Interrupt Controller) is an
529 integrated interrupt controller in the CPU. If you have a single-CPU
530 system which has a processor with a local APIC, you can say Y here to
531 enable and use it. If you say Y here even though your machine doesn't
532 have a local APIC, then the kernel will still run with no slowdown at
533 all. The local APIC supports CPU-generated self-interrupts (timer,
534 performance counters), and the NMI watchdog which detects hard
538 bool "IO-APIC support on uniprocessors"
539 depends on X86_UP_APIC
541 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
542 SMP-capable replacement for PC-style interrupt controllers. Most
543 SMP systems and many recent uniprocessor systems have one.
545 If you have a single-CPU system with an IO-APIC, you can say Y here
546 to use it. If you say Y here even though your machine doesn't have
547 an IO-APIC, then the kernel will still run with no slowdown at all.
549 config X86_LOCAL_APIC
551 depends on X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER)
556 depends on X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER))
559 config X86_VISWS_APIC
566 depends on (MWINCHIP3D || MWINCHIP2 || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MGEODEGX1) && !X86_NUMAQ
570 bool "Machine Check Exception"
571 depends on !X86_VOYAGER
573 Machine Check Exception support allows the processor to notify the
574 kernel if it detects a problem (e.g. overheating, component failure).
575 The action the kernel takes depends on the severity of the problem,
576 ranging from a warning message on the console, to halting the machine.
577 Your processor must be a Pentium or newer to support this - check the
578 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
579 have a design flaw which leads to false MCE events - hence MCE is
580 disabled on all P5 processors, unless explicitly enabled with "mce"
581 as a boot argument. Similarly, if MCE is built in and creates a
582 problem on some new non-standard machine, you can boot with "nomce"
583 to disable it. MCE support simply ignores non-MCE processors like
584 the 386 and 486, so nearly everyone can say Y here.
586 config X86_MCE_NONFATAL
587 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
590 Enabling this feature starts a timer that triggers every 5 seconds which
591 will look at the machine check registers to see if anything happened.
592 Non-fatal problems automatically get corrected (but still logged).
593 Disable this if you don't want to see these messages.
594 Seeing the messages this option prints out may be indicative of dying hardware,
595 or out-of-spec (ie, overclocked) hardware.
596 This option only does something on certain CPUs.
597 (AMD Athlon/Duron and Intel Pentium 4)
599 config X86_MCE_P4THERMAL
600 bool "check for P4 thermal throttling interrupt."
601 depends on X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
603 Enabling this feature will cause a message to be printed when the P4
604 enters thermal throttling.
607 tristate "Toshiba Laptop support"
609 This adds a driver to safely access the System Management Mode of
610 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
611 not work on models with a Phoenix BIOS. The System Management Mode
612 is used to set the BIOS and power saving options on Toshiba portables.
614 For information on utilities to make use of this driver see the
615 Toshiba Linux utilities web site at:
616 <http://www.buzzard.org.uk/toshiba/>.
618 Say Y if you intend to run this kernel on a Toshiba portable.
622 tristate "Dell laptop support"
624 This adds a driver to safely access the System Management Mode
625 of the CPU on the Dell Inspiron 8000. The System Management Mode
626 is used to read cpu temperature and cooling fan status and to
627 control the fans on the I8K portables.
629 This driver has been tested only on the Inspiron 8000 but it may
630 also work with other Dell laptops. You can force loading on other
631 models by passing the parameter `force=1' to the module. Use at
634 For information on utilities to make use of this driver see the
635 I8K Linux utilities web site at:
636 <http://people.debian.org/~dz/i8k/>
638 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
641 config X86_REBOOTFIXUPS
642 bool "Enable X86 board specific fixups for reboot"
646 This enables chipset and/or board specific fixups to be done
647 in order to get reboot to work correctly. This is only needed on
648 some combinations of hardware and BIOS. The symptom, for which
649 this config is intended, is when reboot ends with a stalled/hung
652 Currently, the only fixup is for the Geode GX1/CS5530A/TROM2.1.
655 Say Y if you want to enable the fixup. Currently, it's safe to
656 enable this option even if you don't need it.
660 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
662 If you say Y here and also to "/dev file system support" in the
663 'File systems' section, you will be able to update the microcode on
664 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
665 Pentium III, Pentium 4, Xeon etc. You will obviously need the
666 actual microcode binary data itself which is not shipped with the
669 For latest news and information on obtaining all the required
670 ingredients for this driver, check:
671 <http://www.urbanmyth.org/microcode/>.
673 To compile this driver as a module, choose M here: the
674 module will be called microcode.
677 tristate "/dev/cpu/*/msr - Model-specific register support"
679 This device gives privileged processes access to the x86
680 Model-Specific Registers (MSRs). It is a character device with
681 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
682 MSR accesses are directed to a specific CPU on multi-processor
686 tristate "/dev/cpu/*/cpuid - CPU information support"
688 This device gives processes access to the x86 CPUID instruction to
689 be executed on a specific processor. It is a character device
690 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
693 source "drivers/firmware/Kconfig"
696 prompt "High Memory Support"
702 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
703 However, the address space of 32-bit x86 processors is only 4
704 Gigabytes large. That means that, if you have a large amount of
705 physical memory, not all of it can be "permanently mapped" by the
706 kernel. The physical memory that's not permanently mapped is called
709 If you are compiling a kernel which will never run on a machine with
710 more than 1 Gigabyte total physical RAM, answer "off" here (default
711 choice and suitable for most users). This will result in a "3GB/1GB"
712 split: 3GB are mapped so that each process sees a 3GB virtual memory
713 space and the remaining part of the 4GB virtual memory space is used
714 by the kernel to permanently map as much physical memory as
717 If the machine has between 1 and 4 Gigabytes physical RAM, then
720 If more than 4 Gigabytes is used then answer "64GB" here. This
721 selection turns Intel PAE (Physical Address Extension) mode on.
722 PAE implements 3-level paging on IA32 processors. PAE is fully
723 supported by Linux, PAE mode is implemented on all recent Intel
724 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
725 then the kernel will not boot on CPUs that don't support PAE!
727 The actual amount of total physical memory will either be
728 auto detected or can be forced by using a kernel command line option
729 such as "mem=256M". (Try "man bootparam" or see the documentation of
730 your boot loader (lilo or loadlin) about how to pass options to the
731 kernel at boot time.)
733 If unsure, say "off".
738 Select this if you have a 32-bit processor and between 1 and 4
739 gigabytes of physical RAM.
744 Select this if you have a 32-bit processor and more than 4
745 gigabytes of physical RAM.
751 depends on HIGHMEM64G || HIGHMEM4G
756 depends on HIGHMEM64G
759 # Common NUMA Features
761 bool "Numa Memory Allocation and Scheduler Support"
762 depends on SMP && HIGHMEM64G && (X86_NUMAQ || X86_GENERICARCH || (X86_SUMMIT && ACPI))
764 default y if (X86_NUMAQ || X86_SUMMIT)
765 select SPARSEMEM_STATIC
767 # Need comments to help the hapless user trying to turn on NUMA support
768 comment "NUMA (NUMA-Q) requires SMP, 64GB highmem support"
769 depends on X86_NUMAQ && (!HIGHMEM64G || !SMP)
771 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
772 depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
774 config HAVE_ARCH_BOOTMEM_NODE
779 config ARCH_HAVE_MEMORY_PRESENT
781 depends on DISCONTIGMEM
784 config NEED_NODE_MEMMAP_SIZE
786 depends on DISCONTIGMEM || SPARSEMEM
789 config HAVE_ARCH_ALLOC_REMAP
794 config ARCH_DISCONTIGMEM_ENABLE
798 config ARCH_DISCONTIGMEM_DEFAULT
802 config ARCH_SPARSEMEM_ENABLE
806 config ARCH_SELECT_MEMORY_MODEL
808 depends on ARCH_SPARSEMEM_ENABLE
812 config HAVE_ARCH_EARLY_PFN_TO_NID
818 bool "Allocate 3rd-level pagetables from highmem"
819 depends on HIGHMEM4G || HIGHMEM64G
821 The VM uses one page table entry for each page of physical memory.
822 For systems with a lot of RAM, this can be wasteful of precious
823 low memory. Setting this option will put user-space page table
824 entries in high memory.
826 config MATH_EMULATION
827 bool "Math emulation"
829 Linux can emulate a math coprocessor (used for floating point
830 operations) if you don't have one. 486DX and Pentium processors have
831 a math coprocessor built in, 486SX and 386 do not, unless you added
832 a 487DX or 387, respectively. (The messages during boot time can
833 give you some hints here ["man dmesg"].) Everyone needs either a
834 coprocessor or this emulation.
836 If you don't have a math coprocessor, you need to say Y here; if you
837 say Y here even though you have a coprocessor, the coprocessor will
838 be used nevertheless. (This behavior can be changed with the kernel
839 command line option "no387", which comes handy if your coprocessor
840 is broken. Try "man bootparam" or see the documentation of your boot
841 loader (lilo or loadlin) about how to pass options to the kernel at
842 boot time.) This means that it is a good idea to say Y here if you
843 intend to use this kernel on different machines.
845 More information about the internals of the Linux math coprocessor
846 emulation can be found in <file:arch/i386/math-emu/README>.
848 If you are not sure, say Y; apart from resulting in a 66 KB bigger
849 kernel, it won't hurt.
852 bool "MTRR (Memory Type Range Register) support"
854 On Intel P6 family processors (Pentium Pro, Pentium II and later)
855 the Memory Type Range Registers (MTRRs) may be used to control
856 processor access to memory ranges. This is most useful if you have
857 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
858 allows bus write transfers to be combined into a larger transfer
859 before bursting over the PCI/AGP bus. This can increase performance
860 of image write operations 2.5 times or more. Saying Y here creates a
861 /proc/mtrr file which may be used to manipulate your processor's
862 MTRRs. Typically the X server should use this.
864 This code has a reasonably generic interface so that similar
865 control registers on other processors can be easily supported
868 The Cyrix 6x86, 6x86MX and M II processors have Address Range
869 Registers (ARRs) which provide a similar functionality to MTRRs. For
870 these, the ARRs are used to emulate the MTRRs.
871 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
872 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
873 write-combining. All of these processors are supported by this code
874 and it makes sense to say Y here if you have one of them.
876 Saying Y here also fixes a problem with buggy SMP BIOSes which only
877 set the MTRRs for the boot CPU and not for the secondary CPUs. This
878 can lead to all sorts of problems, so it's good to say Y here.
880 You can safely say Y even if your machine doesn't have MTRRs, you'll
881 just add about 9 KB to your kernel.
883 See <file:Documentation/mtrr.txt> for more information.
886 bool "Boot from EFI support (EXPERIMENTAL)"
890 This enables the the kernel to boot on EFI platforms using
891 system configuration information passed to it from the firmware.
892 This also enables the kernel to use any EFI runtime services that are
893 available (such as the EFI variable services).
895 This option is only useful on systems that have EFI firmware
896 and will result in a kernel image that is ~8k larger. In addition,
897 you must use the latest ELILO loader available at
898 <http://elilo.sourceforge.net> in order to take advantage of
899 kernel initialization using EFI information (neither GRUB nor LILO know
900 anything about EFI). However, even with this option, the resultant
901 kernel should continue to boot on existing non-EFI platforms.
904 bool "Enable kernel irq balancing"
905 depends on SMP && X86_IO_APIC
908 The default yes will allow the kernel to do irq load balancing.
909 Saying no will keep the kernel from doing irq load balancing.
911 # turning this on wastes a bunch of space.
912 # Summit needs it only when NUMA is on
915 depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
919 bool "Use register arguments (EXPERIMENTAL)"
920 depends on EXPERIMENTAL
923 Compile the kernel with -mregparm=3. This uses a different ABI
924 and passes the first three arguments of a function call in registers.
925 This will probably break binary only modules.
927 This feature is only enabled for gcc-3.0 and later - earlier compilers
928 generate incorrect output with certain kernel constructs when
932 bool "Enable seccomp to safely compute untrusted bytecode"
936 This kernel feature is useful for number crunching applications
937 that may need to compute untrusted bytecode during their
938 execution. By using pipes or other transports made available to
939 the process as file descriptors supporting the read/write
940 syscalls, it's possible to isolate those applications in
941 their own address space using seccomp. Once seccomp is
942 enabled via /proc/<pid>/seccomp, it cannot be disabled
943 and the task is only allowed to execute a few safe syscalls
944 defined by each seccomp mode.
946 If unsure, say Y. Only embedded should say N here.
948 source kernel/Kconfig.hz
950 config PHYSICAL_START
951 hex "Physical address where the kernel is loaded" if EMBEDDED
954 This gives the physical address where the kernel is loaded.
955 Primarily used in the case of kexec on panic where the
956 fail safe kernel needs to run at a different address than
959 Don't change this unless you know what you are doing.
962 bool "kexec system call (EXPERIMENTAL)"
963 depends on EXPERIMENTAL
965 kexec is a system call that implements the ability to shutdown your
966 current kernel, and to start another kernel. It is like a reboot
967 but it is indepedent of the system firmware. And like a reboot
968 you can start any kernel with it, not just Linux.
970 The name comes from the similiarity to the exec system call.
972 It is an ongoing process to be certain the hardware in a machine
973 is properly shutdown, so do not be surprised if this code does not
974 initially work for you. It may help to enable device hotplugging
975 support. As of this writing the exact hardware interface is
976 strongly in flux, so no good recommendation can be made.
979 bool "kernel crash dumps (EXPERIMENTAL)"
981 depends on EXPERIMENTAL
984 Generate crash dump after being started by kexec.
988 menu "Power management options (ACPI, APM)"
989 depends on !X86_VOYAGER
991 source kernel/power/Kconfig
993 source "drivers/acpi/Kconfig"
995 menu "APM (Advanced Power Management) BIOS Support"
996 depends on PM && !X86_VISWS
999 tristate "APM (Advanced Power Management) BIOS support"
1002 APM is a BIOS specification for saving power using several different
1003 techniques. This is mostly useful for battery powered laptops with
1004 APM compliant BIOSes. If you say Y here, the system time will be
1005 reset after a RESUME operation, the /proc/apm device will provide
1006 battery status information, and user-space programs will receive
1007 notification of APM "events" (e.g. battery status change).
1009 If you select "Y" here, you can disable actual use of the APM
1010 BIOS by passing the "apm=off" option to the kernel at boot time.
1012 Note that the APM support is almost completely disabled for
1013 machines with more than one CPU.
1015 In order to use APM, you will need supporting software. For location
1016 and more information, read <file:Documentation/pm.txt> and the
1017 Battery Powered Linux mini-HOWTO, available from
1018 <http://www.tldp.org/docs.html#howto>.
1020 This driver does not spin down disk drives (see the hdparm(8)
1021 manpage ("man 8 hdparm") for that), and it doesn't turn off
1022 VESA-compliant "green" monitors.
1024 This driver does not support the TI 4000M TravelMate and the ACER
1025 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1026 desktop machines also don't have compliant BIOSes, and this driver
1027 may cause those machines to panic during the boot phase.
1029 Generally, if you don't have a battery in your machine, there isn't
1030 much point in using this driver and you should say N. If you get
1031 random kernel OOPSes or reboots that don't seem to be related to
1032 anything, try disabling/enabling this option (or disabling/enabling
1035 Some other things you should try when experiencing seemingly random,
1038 1) make sure that you have enough swap space and that it is
1040 2) pass the "no-hlt" option to the kernel
1041 3) switch on floating point emulation in the kernel and pass
1042 the "no387" option to the kernel
1043 4) pass the "floppy=nodma" option to the kernel
1044 5) pass the "mem=4M" option to the kernel (thereby disabling
1045 all but the first 4 MB of RAM)
1046 6) make sure that the CPU is not over clocked.
1047 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1048 8) disable the cache from your BIOS settings
1049 9) install a fan for the video card or exchange video RAM
1050 10) install a better fan for the CPU
1051 11) exchange RAM chips
1052 12) exchange the motherboard.
1054 To compile this driver as a module, choose M here: the
1055 module will be called apm.
1057 config APM_IGNORE_USER_SUSPEND
1058 bool "Ignore USER SUSPEND"
1061 This option will ignore USER SUSPEND requests. On machines with a
1062 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1063 series notebooks, it is necessary to say Y because of a BIOS bug.
1065 config APM_DO_ENABLE
1066 bool "Enable PM at boot time"
1069 Enable APM features at boot time. From page 36 of the APM BIOS
1070 specification: "When disabled, the APM BIOS does not automatically
1071 power manage devices, enter the Standby State, enter the Suspend
1072 State, or take power saving steps in response to CPU Idle calls."
1073 This driver will make CPU Idle calls when Linux is idle (unless this
1074 feature is turned off -- see "Do CPU IDLE calls", below). This
1075 should always save battery power, but more complicated APM features
1076 will be dependent on your BIOS implementation. You may need to turn
1077 this option off if your computer hangs at boot time when using APM
1078 support, or if it beeps continuously instead of suspending. Turn
1079 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1080 T400CDT. This is off by default since most machines do fine without
1084 bool "Make CPU Idle calls when idle"
1087 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1088 On some machines, this can activate improved power savings, such as
1089 a slowed CPU clock rate, when the machine is idle. These idle calls
1090 are made after the idle loop has run for some length of time (e.g.,
1091 333 mS). On some machines, this will cause a hang at boot time or
1092 whenever the CPU becomes idle. (On machines with more than one CPU,
1093 this option does nothing.)
1095 config APM_DISPLAY_BLANK
1096 bool "Enable console blanking using APM"
1099 Enable console blanking using the APM. Some laptops can use this to
1100 turn off the LCD backlight when the screen blanker of the Linux
1101 virtual console blanks the screen. Note that this is only used by
1102 the virtual console screen blanker, and won't turn off the backlight
1103 when using the X Window system. This also doesn't have anything to
1104 do with your VESA-compliant power-saving monitor. Further, this
1105 option doesn't work for all laptops -- it might not turn off your
1106 backlight at all, or it might print a lot of errors to the console,
1107 especially if you are using gpm.
1109 config APM_RTC_IS_GMT
1110 bool "RTC stores time in GMT"
1113 Say Y here if your RTC (Real Time Clock a.k.a. hardware clock)
1114 stores the time in GMT (Greenwich Mean Time). Say N if your RTC
1117 It is in fact recommended to store GMT in your RTC, because then you
1118 don't have to worry about daylight savings time changes. The only
1119 reason not to use GMT in your RTC is if you also run a broken OS
1120 that doesn't understand GMT.
1122 config APM_ALLOW_INTS
1123 bool "Allow interrupts during APM BIOS calls"
1126 Normally we disable external interrupts while we are making calls to
1127 the APM BIOS as a measure to lessen the effects of a badly behaving
1128 BIOS implementation. The BIOS should reenable interrupts if it
1129 needs to. Unfortunately, some BIOSes do not -- especially those in
1130 many of the newer IBM Thinkpads. If you experience hangs when you
1131 suspend, try setting this to Y. Otherwise, say N.
1133 config APM_REAL_MODE_POWER_OFF
1134 bool "Use real mode APM BIOS call to power off"
1137 Use real mode APM BIOS calls to switch off the computer. This is
1138 a work-around for a number of buggy BIOSes. Switch this option on if
1139 your computer crashes instead of powering off properly.
1143 source "arch/i386/kernel/cpu/cpufreq/Kconfig"
1147 menu "Bus options (PCI, PCMCIA, EISA, MCA, ISA)"
1150 bool "PCI support" if !X86_VISWS
1151 depends on !X86_VOYAGER
1152 default y if X86_VISWS
1154 Find out whether you have a PCI motherboard. PCI is the name of a
1155 bus system, i.e. the way the CPU talks to the other stuff inside
1156 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1157 VESA. If you have PCI, say Y, otherwise N.
1159 The PCI-HOWTO, available from
1160 <http://www.tldp.org/docs.html#howto>, contains valuable
1161 information about which PCI hardware does work under Linux and which
1165 prompt "PCI access mode"
1166 depends on PCI && !X86_VISWS
1169 On PCI systems, the BIOS can be used to detect the PCI devices and
1170 determine their configuration. However, some old PCI motherboards
1171 have BIOS bugs and may crash if this is done. Also, some embedded
1172 PCI-based systems don't have any BIOS at all. Linux can also try to
1173 detect the PCI hardware directly without using the BIOS.
1175 With this option, you can specify how Linux should detect the
1176 PCI devices. If you choose "BIOS", the BIOS will be used,
1177 if you choose "Direct", the BIOS won't be used, and if you
1178 choose "MMConfig", then PCI Express MMCONFIG will be used.
1179 If you choose "Any", the kernel will try MMCONFIG, then the
1180 direct access method and falls back to the BIOS if that doesn't
1181 work. If unsure, go with the default, which is "Any".
1186 config PCI_GOMMCONFIG
1199 depends on !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1204 depends on PCI && ((PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1209 depends on PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1212 source "drivers/pci/pcie/Kconfig"
1214 source "drivers/pci/Kconfig"
1222 depends on !(X86_VOYAGER || X86_VISWS)
1224 Find out whether you have ISA slots on your motherboard. ISA is the
1225 name of a bus system, i.e. the way the CPU talks to the other stuff
1226 inside your box. Other bus systems are PCI, EISA, MicroChannel
1227 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1228 newer boards don't support it. If you have ISA, say Y, otherwise N.
1234 The Extended Industry Standard Architecture (EISA) bus was
1235 developed as an open alternative to the IBM MicroChannel bus.
1237 The EISA bus provided some of the features of the IBM MicroChannel
1238 bus while maintaining backward compatibility with cards made for
1239 the older ISA bus. The EISA bus saw limited use between 1988 and
1240 1995 when it was made obsolete by the PCI bus.
1242 Say Y here if you are building a kernel for an EISA-based machine.
1246 source "drivers/eisa/Kconfig"
1249 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1250 default y if X86_VOYAGER
1252 MicroChannel Architecture is found in some IBM PS/2 machines and
1253 laptops. It is a bus system similar to PCI or ISA. See
1254 <file:Documentation/mca.txt> (and especially the web page given
1255 there) before attempting to build an MCA bus kernel.
1257 source "drivers/mca/Kconfig"
1260 tristate "NatSemi SCx200 support"
1261 depends on !X86_VOYAGER
1263 This provides basic support for the National Semiconductor SCx200
1264 processor. Right now this is just a driver for the GPIO pins.
1266 If you don't know what to do here, say N.
1268 This support is also available as a module. If compiled as a
1269 module, it will be called scx200.
1272 bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
1273 depends on SMP && HOTPLUG && EXPERIMENTAL
1275 Say Y here to experiment with turning CPUs off and on. CPUs
1276 can be controlled through /sys/devices/system/cpu.
1280 source "drivers/pcmcia/Kconfig"
1282 source "drivers/pci/hotplug/Kconfig"
1286 menu "Executable file formats"
1288 source "fs/Kconfig.binfmt"
1292 source "net/Kconfig"
1294 source "drivers/Kconfig"
1298 source "arch/i386/oprofile/Kconfig"
1300 source "arch/i386/Kconfig.debug"
1302 source "security/Kconfig"
1304 source "crypto/Kconfig"
1306 source "lib/Kconfig"
1309 # Use the generic interrupt handling code in kernel/irq/:
1311 config GENERIC_HARDIRQS
1315 config GENERIC_IRQ_PROBE
1319 config GENERIC_PENDING_IRQ
1321 depends on GENERIC_HARDIRQS && SMP
1326 depends on SMP && !X86_VOYAGER
1331 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1334 config X86_BIOS_REBOOT
1336 depends on !(X86_VISWS || X86_VOYAGER)
1339 config X86_TRAMPOLINE
1341 depends on X86_SMP || (X86_VOYAGER && SMP)
1346 depends on X86 && !EMBEDDED