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
36 config GENERIC_ISA_DMA
44 config ARCH_MAY_HAVE_PC_FDC
50 menu "Processor type and features"
53 prompt "Subarchitecture Type"
59 Choose this option if your computer is a standard PC or compatible.
64 Select this for an AMD Elan processor.
66 Do not use this option for K6/Athlon/Opteron processors!
68 If unsure, choose "PC-compatible" instead.
73 Voyager is an MCA-based 32-way capable SMP architecture proprietary
74 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
78 If you do not specifically know you have a Voyager based machine,
79 say N here, otherwise the kernel you build will not be bootable.
82 bool "NUMAQ (IBM/Sequent)"
85 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
86 multiquad box. This changes the way that processors are bootstrapped,
87 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
88 You will need a new lynxer.elf file to flash your firmware with - send
89 email to <Martin.Bligh@us.ibm.com>.
92 bool "Summit/EXA (IBM x440)"
95 This option is needed for IBM systems that use the Summit/EXA chipset.
96 In particular, it is needed for the x440.
98 If you don't have one of these computers, you should say N here.
101 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
104 This option is needed for the systems that have more than 8 CPUs
105 and if the system is not of any sub-arch type above.
107 If you don't have such a system, you should say N here.
110 bool "SGI 320/540 (Visual Workstation)"
112 The SGI Visual Workstation series is an IA32-based workstation
113 based on SGI systems chips with some legacy PC hardware attached.
115 Say Y here to create a kernel to run on the SGI 320 or 540.
117 A kernel compiled for the Visual Workstation will not run on PCs
118 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
120 config X86_GENERICARCH
121 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
124 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
125 It is intended for a generic binary kernel.
128 bool "Support for Unisys ES7000 IA32 series"
131 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
132 supposed to run on an IA32-based Unisys ES7000 system.
133 Only choose this option if you have such a system, otherwise you
141 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
143 config X86_SUMMIT_NUMA
146 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
148 config X86_CYCLONE_TIMER
151 depends on X86_SUMMIT || X86_GENERICARCH
153 config ES7000_CLUSTERED_APIC
156 depends on SMP && X86_ES7000 && MPENTIUMIII
161 prompt "Processor family"
167 This is the processor type of your CPU. This information is used for
168 optimizing purposes. In order to compile a kernel that can run on
169 all x86 CPU types (albeit not optimally fast), you can specify
172 The kernel will not necessarily run on earlier architectures than
173 the one you have chosen, e.g. a Pentium optimized kernel will run on
174 a PPro, but not necessarily on a i486.
176 Here are the settings recommended for greatest speed:
177 - "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI
178 486DLC/DLC2, UMC 486SX-S and NexGen Nx586. Only "386" kernels
179 will run on a 386 class machine.
180 - "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
181 SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
182 - "586" for generic Pentium CPUs lacking the TSC
183 (time stamp counter) register.
184 - "Pentium-Classic" for the Intel Pentium.
185 - "Pentium-MMX" for the Intel Pentium MMX.
186 - "Pentium-Pro" for the Intel Pentium Pro.
187 - "Pentium-II" for the Intel Pentium II or pre-Coppermine Celeron.
188 - "Pentium-III" for the Intel Pentium III or Coppermine Celeron.
189 - "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.
190 - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
191 - "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
192 - "Crusoe" for the Transmeta Crusoe series.
193 - "Efficeon" for the Transmeta Efficeon series.
194 - "Winchip-C6" for original IDT Winchip.
195 - "Winchip-2" for IDT Winchip 2.
196 - "Winchip-2A" for IDT Winchips with 3dNow! capabilities.
197 - "GeodeGX1" for Geode GX1 (Cyrix MediaGX).
198 - "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.
199 - "VIA C3-2 for VIA C3-2 "Nehemiah" (model 9 and above).
201 If you don't know what to do, choose "386".
206 Select this for a 486 series processor, either Intel or one of the
207 compatible processors from AMD, Cyrix, IBM, or Intel. Includes DX,
208 DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or
212 bool "586/K5/5x86/6x86/6x86MX"
214 Select this for an 586 or 686 series processor such as the AMD K5,
215 the Cyrix 5x86, 6x86 and 6x86MX. This choice does not
216 assume the RDTSC (Read Time Stamp Counter) instruction.
219 bool "Pentium-Classic"
221 Select this for a Pentium Classic processor with the RDTSC (Read
222 Time Stamp Counter) instruction for benchmarking.
227 Select this for a Pentium with the MMX graphics/multimedia
228 extended instructions.
233 Select this for Intel Pentium Pro chips. This enables the use of
234 Pentium Pro extended instructions, and disables the init-time guard
235 against the f00f bug found in earlier Pentiums.
238 bool "Pentium-II/Celeron(pre-Coppermine)"
240 Select this for Intel chips based on the Pentium-II and
241 pre-Coppermine Celeron core. This option enables an unaligned
242 copy optimization, compiles the kernel with optimization flags
243 tailored for the chip, and applies any applicable Pentium Pro
247 bool "Pentium-III/Celeron(Coppermine)/Pentium-III Xeon"
249 Select this for Intel chips based on the Pentium-III and
250 Celeron-Coppermine core. This option enables use of some
251 extended prefetch instructions in addition to the Pentium II
257 Select this for Intel Pentium M (not Pentium-4 M)
261 bool "Pentium-4/Celeron(P4-based)/Pentium-4 M/Xeon"
263 Select this for Intel Pentium 4 chips. This includes the
264 Pentium 4, P4-based Celeron and Xeon, and Pentium-4 M
265 (not Pentium M) chips. This option enables compile flags
266 optimized for the chip, uses the correct cache shift, and
267 applies any applicable Pentium III optimizations.
270 bool "K6/K6-II/K6-III"
272 Select this for an AMD K6-family processor. Enables use of
273 some extended instructions, and passes appropriate optimization
277 bool "Athlon/Duron/K7"
279 Select this for an AMD Athlon K7-family processor. Enables use of
280 some extended instructions, and passes appropriate optimization
284 bool "Opteron/Athlon64/Hammer/K8"
286 Select this for an AMD Opteron or Athlon64 Hammer-family processor. Enables
287 use of some extended instructions, and passes appropriate optimization
293 Select this for a Transmeta Crusoe processor. Treats the processor
294 like a 586 with TSC, and sets some GCC optimization flags (like a
295 Pentium Pro with no alignment requirements).
300 Select this for a Transmeta Efficeon processor.
305 Select this for an IDT Winchip C6 chip. Linux and GCC
306 treat this chip as a 586TSC with some extended instructions
307 and alignment requirements.
312 Select this for an IDT Winchip-2. Linux and GCC
313 treat this chip as a 586TSC with some extended instructions
314 and alignment requirements.
317 bool "Winchip-2A/Winchip-3"
319 Select this for an IDT Winchip-2A or 3. Linux and GCC
320 treat this chip as a 586TSC with some extended instructions
321 and alignment reqirements. Also enable out of order memory
322 stores for this CPU, which can increase performance of some
328 Select this for a Geode GX1 (Cyrix MediaGX) chip.
331 bool "CyrixIII/VIA-C3"
333 Select this for a Cyrix III or C3 chip. Presently Linux and GCC
334 treat this chip as a generic 586. Whilst the CPU is 686 class,
335 it lacks the cmov extension which gcc assumes is present when
337 Note that Nehemiah (Model 9) and above will not boot with this
338 kernel due to them lacking the 3DNow! instructions used in earlier
339 incarnations of the CPU.
342 bool "VIA C3-2 (Nehemiah)"
344 Select this for a VIA C3 "Nehemiah". Selecting this enables usage
345 of SSE and tells gcc to treat the CPU as a 686.
346 Note, this kernel will not boot on older (pre model 9) C3s.
351 bool "Generic x86 support"
353 Instead of just including optimizations for the selected
354 x86 variant (e.g. PII, Crusoe or Athlon), include some more
355 generic optimizations as well. This will make the kernel
356 perform better on x86 CPUs other than that selected.
358 This is really intended for distributors who need more
359 generic optimizations.
364 # Define implied options from the CPU selection here
376 config X86_L1_CACHE_SHIFT
378 default "7" if MPENTIUM4 || X86_GENERIC
379 default "4" if X86_ELAN || M486 || M386
380 default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MEFFICEON || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2 || MGEODEGX1
381 default "6" if MK7 || MK8 || MPENTIUMM
383 config RWSEM_GENERIC_SPINLOCK
388 config RWSEM_XCHGADD_ALGORITHM
393 config GENERIC_CALIBRATE_DELAY
397 config X86_PPRO_FENCE
399 depends on M686 || M586MMX || M586TSC || M586 || M486 || M386 || MGEODEGX1
404 depends on M586MMX || M586TSC || M586 || M486 || M386
407 config X86_WP_WORKS_OK
427 config X86_ALIGNMENT_16
429 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || X86_ELAN || MK6 || M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
434 depends on MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || MK8 || MEFFICEON
437 config X86_INTEL_USERCOPY
439 depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7 || MEFFICEON
442 config X86_USE_PPRO_CHECKSUM
444 depends on MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2 || MEFFICEON
449 depends on MCYRIXIII || MK7
454 depends on (MWINCHIP3D || MWINCHIP2 || MWINCHIPC6) && MTRR
458 bool "HPET Timer Support"
460 This enables the use of the HPET for the kernel's internal timer.
461 HPET is the next generation timer replacing legacy 8254s.
462 You can safely choose Y here. However, HPET will only be
463 activated if the platform and the BIOS support this feature.
464 Otherwise the 8254 will be used for timing services.
466 Choose N to continue using the legacy 8254 timer.
468 config HPET_EMULATE_RTC
470 depends on HPET_TIMER && RTC=y
474 bool "Symmetric multi-processing support"
476 This enables support for systems with more than one CPU. If you have
477 a system with only one CPU, like most personal computers, say N. If
478 you have a system with more than one CPU, say Y.
480 If you say N here, the kernel will run on single and multiprocessor
481 machines, but will use only one CPU of a multiprocessor machine. If
482 you say Y here, the kernel will run on many, but not all,
483 singleprocessor machines. On a singleprocessor machine, the kernel
484 will run faster if you say N here.
486 Note that if you say Y here and choose architecture "586" or
487 "Pentium" under "Processor family", the kernel will not work on 486
488 architectures. Similarly, multiprocessor kernels for the "PPro"
489 architecture may not work on all Pentium based boards.
491 People using multiprocessor machines who say Y here should also say
492 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
493 Management" code will be disabled if you say Y here.
495 See also the <file:Documentation/smp.txt>,
496 <file:Documentation/i386/IO-APIC.txt>,
497 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
498 <http://www.tldp.org/docs.html#howto>.
500 If you don't know what to do here, say N.
503 int "Maximum number of CPUs (2-255)"
506 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
509 This allows you to specify the maximum number of CPUs which this
510 kernel will support. The maximum supported value is 255 and the
511 minimum value which makes sense is 2.
513 This is purely to save memory - each supported CPU adds
514 approximately eight kilobytes to the kernel image.
517 bool "SMT (Hyperthreading) scheduler support"
521 SMT scheduler support improves the CPU scheduler's decision making
522 when dealing with Intel Pentium 4 chips with HyperThreading at a
523 cost of slightly increased overhead in some places. If unsure say
526 source "kernel/Kconfig.preempt"
529 bool "Local APIC support on uniprocessors"
530 depends on !SMP && !(X86_VISWS || X86_VOYAGER)
532 A local APIC (Advanced Programmable Interrupt Controller) is an
533 integrated interrupt controller in the CPU. If you have a single-CPU
534 system which has a processor with a local APIC, you can say Y here to
535 enable and use it. If you say Y here even though your machine doesn't
536 have a local APIC, then the kernel will still run with no slowdown at
537 all. The local APIC supports CPU-generated self-interrupts (timer,
538 performance counters), and the NMI watchdog which detects hard
542 bool "IO-APIC support on uniprocessors"
543 depends on X86_UP_APIC
545 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
546 SMP-capable replacement for PC-style interrupt controllers. Most
547 SMP systems and many recent uniprocessor systems have one.
549 If you have a single-CPU system with an IO-APIC, you can say Y here
550 to use it. If you say Y here even though your machine doesn't have
551 an IO-APIC, then the kernel will still run with no slowdown at all.
553 config X86_LOCAL_APIC
555 depends on X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER)
560 depends on X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER))
563 config X86_VISWS_APIC
570 depends on (MWINCHIP3D || MWINCHIP2 || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MGEODEGX1) && !X86_NUMAQ
574 bool "Machine Check Exception"
575 depends on !X86_VOYAGER
577 Machine Check Exception support allows the processor to notify the
578 kernel if it detects a problem (e.g. overheating, component failure).
579 The action the kernel takes depends on the severity of the problem,
580 ranging from a warning message on the console, to halting the machine.
581 Your processor must be a Pentium or newer to support this - check the
582 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
583 have a design flaw which leads to false MCE events - hence MCE is
584 disabled on all P5 processors, unless explicitly enabled with "mce"
585 as a boot argument. Similarly, if MCE is built in and creates a
586 problem on some new non-standard machine, you can boot with "nomce"
587 to disable it. MCE support simply ignores non-MCE processors like
588 the 386 and 486, so nearly everyone can say Y here.
590 config X86_MCE_NONFATAL
591 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
594 Enabling this feature starts a timer that triggers every 5 seconds which
595 will look at the machine check registers to see if anything happened.
596 Non-fatal problems automatically get corrected (but still logged).
597 Disable this if you don't want to see these messages.
598 Seeing the messages this option prints out may be indicative of dying hardware,
599 or out-of-spec (ie, overclocked) hardware.
600 This option only does something on certain CPUs.
601 (AMD Athlon/Duron and Intel Pentium 4)
603 config X86_MCE_P4THERMAL
604 bool "check for P4 thermal throttling interrupt."
605 depends on X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
607 Enabling this feature will cause a message to be printed when the P4
608 enters thermal throttling.
611 tristate "Toshiba Laptop support"
613 This adds a driver to safely access the System Management Mode of
614 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
615 not work on models with a Phoenix BIOS. The System Management Mode
616 is used to set the BIOS and power saving options on Toshiba portables.
618 For information on utilities to make use of this driver see the
619 Toshiba Linux utilities web site at:
620 <http://www.buzzard.org.uk/toshiba/>.
622 Say Y if you intend to run this kernel on a Toshiba portable.
626 tristate "Dell laptop support"
628 This adds a driver to safely access the System Management Mode
629 of the CPU on the Dell Inspiron 8000. The System Management Mode
630 is used to read cpu temperature and cooling fan status and to
631 control the fans on the I8K portables.
633 This driver has been tested only on the Inspiron 8000 but it may
634 also work with other Dell laptops. You can force loading on other
635 models by passing the parameter `force=1' to the module. Use at
638 For information on utilities to make use of this driver see the
639 I8K Linux utilities web site at:
640 <http://people.debian.org/~dz/i8k/>
642 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
645 config X86_REBOOTFIXUPS
646 bool "Enable X86 board specific fixups for reboot"
650 This enables chipset and/or board specific fixups to be done
651 in order to get reboot to work correctly. This is only needed on
652 some combinations of hardware and BIOS. The symptom, for which
653 this config is intended, is when reboot ends with a stalled/hung
656 Currently, the only fixup is for the Geode GX1/CS5530A/TROM2.1.
659 Say Y if you want to enable the fixup. Currently, it's safe to
660 enable this option even if you don't need it.
664 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
666 If you say Y here and also to "/dev file system support" in the
667 'File systems' section, you will be able to update the microcode on
668 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
669 Pentium III, Pentium 4, Xeon etc. You will obviously need the
670 actual microcode binary data itself which is not shipped with the
673 For latest news and information on obtaining all the required
674 ingredients for this driver, check:
675 <http://www.urbanmyth.org/microcode/>.
677 To compile this driver as a module, choose M here: the
678 module will be called microcode.
681 tristate "/dev/cpu/*/msr - Model-specific register support"
683 This device gives privileged processes access to the x86
684 Model-Specific Registers (MSRs). It is a character device with
685 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
686 MSR accesses are directed to a specific CPU on multi-processor
690 tristate "/dev/cpu/*/cpuid - CPU information support"
692 This device gives processes access to the x86 CPUID instruction to
693 be executed on a specific processor. It is a character device
694 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
697 source "drivers/firmware/Kconfig"
700 prompt "High Memory Support"
706 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
707 However, the address space of 32-bit x86 processors is only 4
708 Gigabytes large. That means that, if you have a large amount of
709 physical memory, not all of it can be "permanently mapped" by the
710 kernel. The physical memory that's not permanently mapped is called
713 If you are compiling a kernel which will never run on a machine with
714 more than 1 Gigabyte total physical RAM, answer "off" here (default
715 choice and suitable for most users). This will result in a "3GB/1GB"
716 split: 3GB are mapped so that each process sees a 3GB virtual memory
717 space and the remaining part of the 4GB virtual memory space is used
718 by the kernel to permanently map as much physical memory as
721 If the machine has between 1 and 4 Gigabytes physical RAM, then
724 If more than 4 Gigabytes is used then answer "64GB" here. This
725 selection turns Intel PAE (Physical Address Extension) mode on.
726 PAE implements 3-level paging on IA32 processors. PAE is fully
727 supported by Linux, PAE mode is implemented on all recent Intel
728 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
729 then the kernel will not boot on CPUs that don't support PAE!
731 The actual amount of total physical memory will either be
732 auto detected or can be forced by using a kernel command line option
733 such as "mem=256M". (Try "man bootparam" or see the documentation of
734 your boot loader (lilo or loadlin) about how to pass options to the
735 kernel at boot time.)
737 If unsure, say "off".
742 Select this if you have a 32-bit processor and between 1 and 4
743 gigabytes of physical RAM.
748 Select this if you have a 32-bit processor and more than 4
749 gigabytes of physical RAM.
755 depends on HIGHMEM64G || HIGHMEM4G
760 depends on HIGHMEM64G
763 # Common NUMA Features
765 bool "Numa Memory Allocation and Scheduler Support"
766 depends on SMP && HIGHMEM64G && (X86_NUMAQ || X86_GENERICARCH || (X86_SUMMIT && ACPI))
768 default y if (X86_NUMAQ || X86_SUMMIT)
769 select SPARSEMEM_STATIC
771 # Need comments to help the hapless user trying to turn on NUMA support
772 comment "NUMA (NUMA-Q) requires SMP, 64GB highmem support"
773 depends on X86_NUMAQ && (!HIGHMEM64G || !SMP)
775 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
776 depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
778 config HAVE_ARCH_BOOTMEM_NODE
783 config ARCH_HAVE_MEMORY_PRESENT
785 depends on DISCONTIGMEM
788 config NEED_NODE_MEMMAP_SIZE
790 depends on DISCONTIGMEM || SPARSEMEM
793 config HAVE_ARCH_ALLOC_REMAP
798 config ARCH_DISCONTIGMEM_ENABLE
802 config ARCH_DISCONTIGMEM_DEFAULT
806 config ARCH_SPARSEMEM_ENABLE
810 config ARCH_SELECT_MEMORY_MODEL
812 depends on ARCH_SPARSEMEM_ENABLE
816 config HAVE_ARCH_EARLY_PFN_TO_NID
822 bool "Allocate 3rd-level pagetables from highmem"
823 depends on HIGHMEM4G || HIGHMEM64G
825 The VM uses one page table entry for each page of physical memory.
826 For systems with a lot of RAM, this can be wasteful of precious
827 low memory. Setting this option will put user-space page table
828 entries in high memory.
830 config MATH_EMULATION
831 bool "Math emulation"
833 Linux can emulate a math coprocessor (used for floating point
834 operations) if you don't have one. 486DX and Pentium processors have
835 a math coprocessor built in, 486SX and 386 do not, unless you added
836 a 487DX or 387, respectively. (The messages during boot time can
837 give you some hints here ["man dmesg"].) Everyone needs either a
838 coprocessor or this emulation.
840 If you don't have a math coprocessor, you need to say Y here; if you
841 say Y here even though you have a coprocessor, the coprocessor will
842 be used nevertheless. (This behavior can be changed with the kernel
843 command line option "no387", which comes handy if your coprocessor
844 is broken. Try "man bootparam" or see the documentation of your boot
845 loader (lilo or loadlin) about how to pass options to the kernel at
846 boot time.) This means that it is a good idea to say Y here if you
847 intend to use this kernel on different machines.
849 More information about the internals of the Linux math coprocessor
850 emulation can be found in <file:arch/i386/math-emu/README>.
852 If you are not sure, say Y; apart from resulting in a 66 KB bigger
853 kernel, it won't hurt.
856 bool "MTRR (Memory Type Range Register) support"
858 On Intel P6 family processors (Pentium Pro, Pentium II and later)
859 the Memory Type Range Registers (MTRRs) may be used to control
860 processor access to memory ranges. This is most useful if you have
861 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
862 allows bus write transfers to be combined into a larger transfer
863 before bursting over the PCI/AGP bus. This can increase performance
864 of image write operations 2.5 times or more. Saying Y here creates a
865 /proc/mtrr file which may be used to manipulate your processor's
866 MTRRs. Typically the X server should use this.
868 This code has a reasonably generic interface so that similar
869 control registers on other processors can be easily supported
872 The Cyrix 6x86, 6x86MX and M II processors have Address Range
873 Registers (ARRs) which provide a similar functionality to MTRRs. For
874 these, the ARRs are used to emulate the MTRRs.
875 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
876 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
877 write-combining. All of these processors are supported by this code
878 and it makes sense to say Y here if you have one of them.
880 Saying Y here also fixes a problem with buggy SMP BIOSes which only
881 set the MTRRs for the boot CPU and not for the secondary CPUs. This
882 can lead to all sorts of problems, so it's good to say Y here.
884 You can safely say Y even if your machine doesn't have MTRRs, you'll
885 just add about 9 KB to your kernel.
887 See <file:Documentation/mtrr.txt> for more information.
890 bool "Boot from EFI support (EXPERIMENTAL)"
894 This enables the the kernel to boot on EFI platforms using
895 system configuration information passed to it from the firmware.
896 This also enables the kernel to use any EFI runtime services that are
897 available (such as the EFI variable services).
899 This option is only useful on systems that have EFI firmware
900 and will result in a kernel image that is ~8k larger. In addition,
901 you must use the latest ELILO loader available at
902 <http://elilo.sourceforge.net> in order to take advantage of
903 kernel initialization using EFI information (neither GRUB nor LILO know
904 anything about EFI). However, even with this option, the resultant
905 kernel should continue to boot on existing non-EFI platforms.
908 bool "Enable kernel irq balancing"
909 depends on SMP && X86_IO_APIC
912 The default yes will allow the kernel to do irq load balancing.
913 Saying no will keep the kernel from doing irq load balancing.
915 # turning this on wastes a bunch of space.
916 # Summit needs it only when NUMA is on
919 depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
923 bool "Use register arguments (EXPERIMENTAL)"
924 depends on EXPERIMENTAL
927 Compile the kernel with -mregparm=3. This uses a different ABI
928 and passes the first three arguments of a function call in registers.
929 This will probably break binary only modules.
931 This feature is only enabled for gcc-3.0 and later - earlier compilers
932 generate incorrect output with certain kernel constructs when
936 bool "Enable seccomp to safely compute untrusted bytecode"
940 This kernel feature is useful for number crunching applications
941 that may need to compute untrusted bytecode during their
942 execution. By using pipes or other transports made available to
943 the process as file descriptors supporting the read/write
944 syscalls, it's possible to isolate those applications in
945 their own address space using seccomp. Once seccomp is
946 enabled via /proc/<pid>/seccomp, it cannot be disabled
947 and the task is only allowed to execute a few safe syscalls
948 defined by each seccomp mode.
950 If unsure, say Y. Only embedded should say N here.
952 source kernel/Kconfig.hz
954 config PHYSICAL_START
955 hex "Physical address where the kernel is loaded" if EMBEDDED
958 This gives the physical address where the kernel is loaded.
959 Primarily used in the case of kexec on panic where the
960 fail safe kernel needs to run at a different address than
963 Don't change this unless you know what you are doing.
966 bool "kexec system call (EXPERIMENTAL)"
967 depends on EXPERIMENTAL
969 kexec is a system call that implements the ability to shutdown your
970 current kernel, and to start another kernel. It is like a reboot
971 but it is indepedent of the system firmware. And like a reboot
972 you can start any kernel with it, not just Linux.
974 The name comes from the similiarity to the exec system call.
976 It is an ongoing process to be certain the hardware in a machine
977 is properly shutdown, so do not be surprised if this code does not
978 initially work for you. It may help to enable device hotplugging
979 support. As of this writing the exact hardware interface is
980 strongly in flux, so no good recommendation can be made.
983 bool "kernel crash dumps (EXPERIMENTAL)"
985 depends on EXPERIMENTAL
988 Generate crash dump after being started by kexec.
992 menu "Power management options (ACPI, APM)"
993 depends on !X86_VOYAGER
995 source kernel/power/Kconfig
997 source "drivers/acpi/Kconfig"
999 menu "APM (Advanced Power Management) BIOS Support"
1000 depends on PM && !X86_VISWS
1003 tristate "APM (Advanced Power Management) BIOS support"
1006 APM is a BIOS specification for saving power using several different
1007 techniques. This is mostly useful for battery powered laptops with
1008 APM compliant BIOSes. If you say Y here, the system time will be
1009 reset after a RESUME operation, the /proc/apm device will provide
1010 battery status information, and user-space programs will receive
1011 notification of APM "events" (e.g. battery status change).
1013 If you select "Y" here, you can disable actual use of the APM
1014 BIOS by passing the "apm=off" option to the kernel at boot time.
1016 Note that the APM support is almost completely disabled for
1017 machines with more than one CPU.
1019 In order to use APM, you will need supporting software. For location
1020 and more information, read <file:Documentation/pm.txt> and the
1021 Battery Powered Linux mini-HOWTO, available from
1022 <http://www.tldp.org/docs.html#howto>.
1024 This driver does not spin down disk drives (see the hdparm(8)
1025 manpage ("man 8 hdparm") for that), and it doesn't turn off
1026 VESA-compliant "green" monitors.
1028 This driver does not support the TI 4000M TravelMate and the ACER
1029 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1030 desktop machines also don't have compliant BIOSes, and this driver
1031 may cause those machines to panic during the boot phase.
1033 Generally, if you don't have a battery in your machine, there isn't
1034 much point in using this driver and you should say N. If you get
1035 random kernel OOPSes or reboots that don't seem to be related to
1036 anything, try disabling/enabling this option (or disabling/enabling
1039 Some other things you should try when experiencing seemingly random,
1042 1) make sure that you have enough swap space and that it is
1044 2) pass the "no-hlt" option to the kernel
1045 3) switch on floating point emulation in the kernel and pass
1046 the "no387" option to the kernel
1047 4) pass the "floppy=nodma" option to the kernel
1048 5) pass the "mem=4M" option to the kernel (thereby disabling
1049 all but the first 4 MB of RAM)
1050 6) make sure that the CPU is not over clocked.
1051 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1052 8) disable the cache from your BIOS settings
1053 9) install a fan for the video card or exchange video RAM
1054 10) install a better fan for the CPU
1055 11) exchange RAM chips
1056 12) exchange the motherboard.
1058 To compile this driver as a module, choose M here: the
1059 module will be called apm.
1061 config APM_IGNORE_USER_SUSPEND
1062 bool "Ignore USER SUSPEND"
1065 This option will ignore USER SUSPEND requests. On machines with a
1066 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1067 series notebooks, it is necessary to say Y because of a BIOS bug.
1069 config APM_DO_ENABLE
1070 bool "Enable PM at boot time"
1073 Enable APM features at boot time. From page 36 of the APM BIOS
1074 specification: "When disabled, the APM BIOS does not automatically
1075 power manage devices, enter the Standby State, enter the Suspend
1076 State, or take power saving steps in response to CPU Idle calls."
1077 This driver will make CPU Idle calls when Linux is idle (unless this
1078 feature is turned off -- see "Do CPU IDLE calls", below). This
1079 should always save battery power, but more complicated APM features
1080 will be dependent on your BIOS implementation. You may need to turn
1081 this option off if your computer hangs at boot time when using APM
1082 support, or if it beeps continuously instead of suspending. Turn
1083 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1084 T400CDT. This is off by default since most machines do fine without
1088 bool "Make CPU Idle calls when idle"
1091 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1092 On some machines, this can activate improved power savings, such as
1093 a slowed CPU clock rate, when the machine is idle. These idle calls
1094 are made after the idle loop has run for some length of time (e.g.,
1095 333 mS). On some machines, this will cause a hang at boot time or
1096 whenever the CPU becomes idle. (On machines with more than one CPU,
1097 this option does nothing.)
1099 config APM_DISPLAY_BLANK
1100 bool "Enable console blanking using APM"
1103 Enable console blanking using the APM. Some laptops can use this to
1104 turn off the LCD backlight when the screen blanker of the Linux
1105 virtual console blanks the screen. Note that this is only used by
1106 the virtual console screen blanker, and won't turn off the backlight
1107 when using the X Window system. This also doesn't have anything to
1108 do with your VESA-compliant power-saving monitor. Further, this
1109 option doesn't work for all laptops -- it might not turn off your
1110 backlight at all, or it might print a lot of errors to the console,
1111 especially if you are using gpm.
1113 config APM_RTC_IS_GMT
1114 bool "RTC stores time in GMT"
1117 Say Y here if your RTC (Real Time Clock a.k.a. hardware clock)
1118 stores the time in GMT (Greenwich Mean Time). Say N if your RTC
1121 It is in fact recommended to store GMT in your RTC, because then you
1122 don't have to worry about daylight savings time changes. The only
1123 reason not to use GMT in your RTC is if you also run a broken OS
1124 that doesn't understand GMT.
1126 config APM_ALLOW_INTS
1127 bool "Allow interrupts during APM BIOS calls"
1130 Normally we disable external interrupts while we are making calls to
1131 the APM BIOS as a measure to lessen the effects of a badly behaving
1132 BIOS implementation. The BIOS should reenable interrupts if it
1133 needs to. Unfortunately, some BIOSes do not -- especially those in
1134 many of the newer IBM Thinkpads. If you experience hangs when you
1135 suspend, try setting this to Y. Otherwise, say N.
1137 config APM_REAL_MODE_POWER_OFF
1138 bool "Use real mode APM BIOS call to power off"
1141 Use real mode APM BIOS calls to switch off the computer. This is
1142 a work-around for a number of buggy BIOSes. Switch this option on if
1143 your computer crashes instead of powering off properly.
1147 source "arch/i386/kernel/cpu/cpufreq/Kconfig"
1151 menu "Bus options (PCI, PCMCIA, EISA, MCA, ISA)"
1154 bool "PCI support" if !X86_VISWS
1155 depends on !X86_VOYAGER
1156 default y if X86_VISWS
1158 Find out whether you have a PCI motherboard. PCI is the name of a
1159 bus system, i.e. the way the CPU talks to the other stuff inside
1160 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1161 VESA. If you have PCI, say Y, otherwise N.
1163 The PCI-HOWTO, available from
1164 <http://www.tldp.org/docs.html#howto>, contains valuable
1165 information about which PCI hardware does work under Linux and which
1169 prompt "PCI access mode"
1170 depends on PCI && !X86_VISWS
1173 On PCI systems, the BIOS can be used to detect the PCI devices and
1174 determine their configuration. However, some old PCI motherboards
1175 have BIOS bugs and may crash if this is done. Also, some embedded
1176 PCI-based systems don't have any BIOS at all. Linux can also try to
1177 detect the PCI hardware directly without using the BIOS.
1179 With this option, you can specify how Linux should detect the
1180 PCI devices. If you choose "BIOS", the BIOS will be used,
1181 if you choose "Direct", the BIOS won't be used, and if you
1182 choose "MMConfig", then PCI Express MMCONFIG will be used.
1183 If you choose "Any", the kernel will try MMCONFIG, then the
1184 direct access method and falls back to the BIOS if that doesn't
1185 work. If unsure, go with the default, which is "Any".
1190 config PCI_GOMMCONFIG
1203 depends on !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1208 depends on PCI && ((PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1213 depends on PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1216 source "drivers/pci/pcie/Kconfig"
1218 source "drivers/pci/Kconfig"
1226 depends on !(X86_VOYAGER || X86_VISWS)
1228 Find out whether you have ISA slots on your motherboard. ISA is the
1229 name of a bus system, i.e. the way the CPU talks to the other stuff
1230 inside your box. Other bus systems are PCI, EISA, MicroChannel
1231 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1232 newer boards don't support it. If you have ISA, say Y, otherwise N.
1238 The Extended Industry Standard Architecture (EISA) bus was
1239 developed as an open alternative to the IBM MicroChannel bus.
1241 The EISA bus provided some of the features of the IBM MicroChannel
1242 bus while maintaining backward compatibility with cards made for
1243 the older ISA bus. The EISA bus saw limited use between 1988 and
1244 1995 when it was made obsolete by the PCI bus.
1246 Say Y here if you are building a kernel for an EISA-based machine.
1250 source "drivers/eisa/Kconfig"
1253 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1254 default y if X86_VOYAGER
1256 MicroChannel Architecture is found in some IBM PS/2 machines and
1257 laptops. It is a bus system similar to PCI or ISA. See
1258 <file:Documentation/mca.txt> (and especially the web page given
1259 there) before attempting to build an MCA bus kernel.
1261 source "drivers/mca/Kconfig"
1264 tristate "NatSemi SCx200 support"
1265 depends on !X86_VOYAGER
1267 This provides basic support for the National Semiconductor SCx200
1268 processor. Right now this is just a driver for the GPIO pins.
1270 If you don't know what to do here, say N.
1272 This support is also available as a module. If compiled as a
1273 module, it will be called scx200.
1276 bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
1277 depends on SMP && HOTPLUG && EXPERIMENTAL
1279 Say Y here to experiment with turning CPUs off and on. CPUs
1280 can be controlled through /sys/devices/system/cpu.
1284 source "drivers/pcmcia/Kconfig"
1286 source "drivers/pci/hotplug/Kconfig"
1290 menu "Executable file formats"
1292 source "fs/Kconfig.binfmt"
1296 source "net/Kconfig"
1298 source "drivers/Kconfig"
1302 source "arch/i386/oprofile/Kconfig"
1304 source "arch/i386/Kconfig.debug"
1306 source "security/Kconfig"
1308 source "crypto/Kconfig"
1310 source "lib/Kconfig"
1313 # Use the generic interrupt handling code in kernel/irq/:
1315 config GENERIC_HARDIRQS
1319 config GENERIC_IRQ_PROBE
1323 config GENERIC_PENDING_IRQ
1325 depends on GENERIC_HARDIRQS && SMP
1330 depends on SMP && !X86_VOYAGER
1335 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1338 config X86_BIOS_REBOOT
1340 depends on !(X86_VISWS || X86_VOYAGER)
1343 config X86_TRAMPOLINE
1345 depends on X86_SMP || (X86_VOYAGER && SMP)
1350 depends on X86 && !EMBEDDED