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.
21 config CLOCKSOURCE_WATCHDOG
25 config LOCKDEP_SUPPORT
29 config STACKTRACE_SUPPORT
33 config SEMAPHORE_SLEEPERS
52 config GENERIC_ISA_DMA
65 config GENERIC_HWEIGHT
69 config ARCH_MAY_HAVE_PC_FDC
79 menu "Processor type and features"
82 bool "Symmetric multi-processing support"
84 This enables support for systems with more than one CPU. If you have
85 a system with only one CPU, like most personal computers, say N. If
86 you have a system with more than one CPU, say Y.
88 If you say N here, the kernel will run on single and multiprocessor
89 machines, but will use only one CPU of a multiprocessor machine. If
90 you say Y here, the kernel will run on many, but not all,
91 singleprocessor machines. On a singleprocessor machine, the kernel
92 will run faster if you say N here.
94 Note that if you say Y here and choose architecture "586" or
95 "Pentium" under "Processor family", the kernel will not work on 486
96 architectures. Similarly, multiprocessor kernels for the "PPro"
97 architecture may not work on all Pentium based boards.
99 People using multiprocessor machines who say Y here should also say
100 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
101 Management" code will be disabled if you say Y here.
103 See also the <file:Documentation/smp.txt>,
104 <file:Documentation/i386/IO-APIC.txt>,
105 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
106 <http://www.tldp.org/docs.html#howto>.
108 If you don't know what to do here, say N.
111 prompt "Subarchitecture Type"
117 Choose this option if your computer is a standard PC or compatible.
122 Select this for an AMD Elan processor.
124 Do not use this option for K6/Athlon/Opteron processors!
126 If unsure, choose "PC-compatible" instead.
131 Voyager is an MCA-based 32-way capable SMP architecture proprietary
132 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
136 If you do not specifically know you have a Voyager based machine,
137 say N here, otherwise the kernel you build will not be bootable.
140 bool "NUMAQ (IBM/Sequent)"
144 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
145 multiquad box. This changes the way that processors are bootstrapped,
146 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
147 You will need a new lynxer.elf file to flash your firmware with - send
148 email to <Martin.Bligh@us.ibm.com>.
151 bool "Summit/EXA (IBM x440)"
154 This option is needed for IBM systems that use the Summit/EXA chipset.
155 In particular, it is needed for the x440.
157 If you don't have one of these computers, you should say N here.
158 If you want to build a NUMA kernel, you must select ACPI.
161 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
164 This option is needed for the systems that have more than 8 CPUs
165 and if the system is not of any sub-arch type above.
167 If you don't have such a system, you should say N here.
170 bool "SGI 320/540 (Visual Workstation)"
172 The SGI Visual Workstation series is an IA32-based workstation
173 based on SGI systems chips with some legacy PC hardware attached.
175 Say Y here to create a kernel to run on the SGI 320 or 540.
177 A kernel compiled for the Visual Workstation will not run on PCs
178 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
180 config X86_GENERICARCH
181 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
183 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
184 It is intended for a generic binary kernel.
185 If you want a NUMA kernel, select ACPI. We need SRAT for NUMA.
188 bool "Support for Unisys ES7000 IA32 series"
191 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
192 supposed to run on an IA32-based Unisys ES7000 system.
193 Only choose this option if you have such a system, otherwise you
199 bool "Paravirtualization support (EXPERIMENTAL)"
200 depends on EXPERIMENTAL
201 depends on !(X86_VISWS || X86_VOYAGER)
203 Paravirtualization is a way of running multiple instances of
204 Linux on the same machine, under a hypervisor. This option
205 changes the kernel so it can modify itself when it is run
206 under a hypervisor, improving performance significantly.
207 However, when run without a hypervisor the kernel is
208 theoretically slower. If in doubt, say N.
211 bool "VMI Paravirt-ops support"
212 depends on PARAVIRT && !NO_HZ
215 VMI provides a paravirtualized interface to multiple hypervisors
216 include VMware ESX server and Xen by connecting to a ROM module
217 provided by the hypervisor.
222 depends on ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)
225 config HAVE_ARCH_PARSE_SRAT
230 config X86_SUMMIT_NUMA
233 depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)
235 config X86_CYCLONE_TIMER
238 depends on X86_SUMMIT || X86_GENERICARCH
240 config ES7000_CLUSTERED_APIC
243 depends on SMP && X86_ES7000 && MPENTIUMIII
245 source "arch/i386/Kconfig.cpu"
248 bool "HPET Timer Support"
250 This enables the use of the HPET for the kernel's internal timer.
251 HPET is the next generation timer replacing legacy 8254s.
252 You can safely choose Y here. However, HPET will only be
253 activated if the platform and the BIOS support this feature.
254 Otherwise the 8254 will be used for timing services.
256 Choose N to continue using the legacy 8254 timer.
258 config HPET_EMULATE_RTC
260 depends on HPET_TIMER && RTC=y
264 int "Maximum number of CPUs (2-255)"
267 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
270 This allows you to specify the maximum number of CPUs which this
271 kernel will support. The maximum supported value is 255 and the
272 minimum value which makes sense is 2.
274 This is purely to save memory - each supported CPU adds
275 approximately eight kilobytes to the kernel image.
278 bool "SMT (Hyperthreading) scheduler support"
281 SMT scheduler support improves the CPU scheduler's decision making
282 when dealing with Intel Pentium 4 chips with HyperThreading at a
283 cost of slightly increased overhead in some places. If unsure say
287 bool "Multi-core scheduler support"
291 Multi-core scheduler support improves the CPU scheduler's decision
292 making when dealing with multi-core CPU chips at a cost of slightly
293 increased overhead in some places. If unsure say N here.
295 source "kernel/Kconfig.preempt"
298 bool "Local APIC support on uniprocessors"
299 depends on !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
301 A local APIC (Advanced Programmable Interrupt Controller) is an
302 integrated interrupt controller in the CPU. If you have a single-CPU
303 system which has a processor with a local APIC, you can say Y here to
304 enable and use it. If you say Y here even though your machine doesn't
305 have a local APIC, then the kernel will still run with no slowdown at
306 all. The local APIC supports CPU-generated self-interrupts (timer,
307 performance counters), and the NMI watchdog which detects hard
311 bool "IO-APIC support on uniprocessors"
312 depends on X86_UP_APIC
314 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
315 SMP-capable replacement for PC-style interrupt controllers. Most
316 SMP systems and many recent uniprocessor systems have one.
318 If you have a single-CPU system with an IO-APIC, you can say Y here
319 to use it. If you say Y here even though your machine doesn't have
320 an IO-APIC, then the kernel will still run with no slowdown at all.
322 config X86_LOCAL_APIC
324 depends on X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH
329 depends on X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH
332 config X86_VISWS_APIC
338 bool "Machine Check Exception"
339 depends on !X86_VOYAGER
341 Machine Check Exception support allows the processor to notify the
342 kernel if it detects a problem (e.g. overheating, component failure).
343 The action the kernel takes depends on the severity of the problem,
344 ranging from a warning message on the console, to halting the machine.
345 Your processor must be a Pentium or newer to support this - check the
346 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
347 have a design flaw which leads to false MCE events - hence MCE is
348 disabled on all P5 processors, unless explicitly enabled with "mce"
349 as a boot argument. Similarly, if MCE is built in and creates a
350 problem on some new non-standard machine, you can boot with "nomce"
351 to disable it. MCE support simply ignores non-MCE processors like
352 the 386 and 486, so nearly everyone can say Y here.
354 config X86_MCE_NONFATAL
355 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
358 Enabling this feature starts a timer that triggers every 5 seconds which
359 will look at the machine check registers to see if anything happened.
360 Non-fatal problems automatically get corrected (but still logged).
361 Disable this if you don't want to see these messages.
362 Seeing the messages this option prints out may be indicative of dying hardware,
363 or out-of-spec (ie, overclocked) hardware.
364 This option only does something on certain CPUs.
365 (AMD Athlon/Duron and Intel Pentium 4)
367 config X86_MCE_P4THERMAL
368 bool "check for P4 thermal throttling interrupt."
369 depends on X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
371 Enabling this feature will cause a message to be printed when the P4
372 enters thermal throttling.
376 bool "Enable VM86 support" if EMBEDDED
378 This option is required by programs like DOSEMU to run 16-bit legacy
379 code on X86 processors. It also may be needed by software like
380 XFree86 to initialize some video cards via BIOS. Disabling this
381 option saves about 6k.
384 tristate "Toshiba Laptop support"
386 This adds a driver to safely access the System Management Mode of
387 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
388 not work on models with a Phoenix BIOS. The System Management Mode
389 is used to set the BIOS and power saving options on Toshiba portables.
391 For information on utilities to make use of this driver see the
392 Toshiba Linux utilities web site at:
393 <http://www.buzzard.org.uk/toshiba/>.
395 Say Y if you intend to run this kernel on a Toshiba portable.
399 tristate "Dell laptop support"
401 This adds a driver to safely access the System Management Mode
402 of the CPU on the Dell Inspiron 8000. The System Management Mode
403 is used to read cpu temperature and cooling fan status and to
404 control the fans on the I8K portables.
406 This driver has been tested only on the Inspiron 8000 but it may
407 also work with other Dell laptops. You can force loading on other
408 models by passing the parameter `force=1' to the module. Use at
411 For information on utilities to make use of this driver see the
412 I8K Linux utilities web site at:
413 <http://people.debian.org/~dz/i8k/>
415 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
418 config X86_REBOOTFIXUPS
419 bool "Enable X86 board specific fixups for reboot"
423 This enables chipset and/or board specific fixups to be done
424 in order to get reboot to work correctly. This is only needed on
425 some combinations of hardware and BIOS. The symptom, for which
426 this config is intended, is when reboot ends with a stalled/hung
429 Currently, the only fixup is for the Geode GX1/CS5530A/TROM2.1.
432 Say Y if you want to enable the fixup. Currently, it's safe to
433 enable this option even if you don't need it.
437 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
440 If you say Y here and also to "/dev file system support" in the
441 'File systems' section, you will be able to update the microcode on
442 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
443 Pentium III, Pentium 4, Xeon etc. You will obviously need the
444 actual microcode binary data itself which is not shipped with the
447 For latest news and information on obtaining all the required
448 ingredients for this driver, check:
449 <http://www.urbanmyth.org/microcode/>.
451 To compile this driver as a module, choose M here: the
452 module will be called microcode.
454 config MICROCODE_OLD_INTERFACE
460 tristate "/dev/cpu/*/msr - Model-specific register support"
462 This device gives privileged processes access to the x86
463 Model-Specific Registers (MSRs). It is a character device with
464 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
465 MSR accesses are directed to a specific CPU on multi-processor
469 tristate "/dev/cpu/*/cpuid - CPU information support"
471 This device gives processes access to the x86 CPUID instruction to
472 be executed on a specific processor. It is a character device
473 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
476 source "drivers/firmware/Kconfig"
479 prompt "High Memory Support"
480 default HIGHMEM4G if !X86_NUMAQ
481 default HIGHMEM64G if X86_NUMAQ
485 depends on !X86_NUMAQ
487 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
488 However, the address space of 32-bit x86 processors is only 4
489 Gigabytes large. That means that, if you have a large amount of
490 physical memory, not all of it can be "permanently mapped" by the
491 kernel. The physical memory that's not permanently mapped is called
494 If you are compiling a kernel which will never run on a machine with
495 more than 1 Gigabyte total physical RAM, answer "off" here (default
496 choice and suitable for most users). This will result in a "3GB/1GB"
497 split: 3GB are mapped so that each process sees a 3GB virtual memory
498 space and the remaining part of the 4GB virtual memory space is used
499 by the kernel to permanently map as much physical memory as
502 If the machine has between 1 and 4 Gigabytes physical RAM, then
505 If more than 4 Gigabytes is used then answer "64GB" here. This
506 selection turns Intel PAE (Physical Address Extension) mode on.
507 PAE implements 3-level paging on IA32 processors. PAE is fully
508 supported by Linux, PAE mode is implemented on all recent Intel
509 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
510 then the kernel will not boot on CPUs that don't support PAE!
512 The actual amount of total physical memory will either be
513 auto detected or can be forced by using a kernel command line option
514 such as "mem=256M". (Try "man bootparam" or see the documentation of
515 your boot loader (lilo or loadlin) about how to pass options to the
516 kernel at boot time.)
518 If unsure, say "off".
522 depends on !X86_NUMAQ
524 Select this if you have a 32-bit processor and between 1 and 4
525 gigabytes of physical RAM.
529 depends on X86_CMPXCHG64
531 Select this if you have a 32-bit processor and more than 4
532 gigabytes of physical RAM.
537 depends on EXPERIMENTAL
538 prompt "Memory split" if EMBEDDED
541 Select the desired split between kernel and user memory.
543 If the address range available to the kernel is less than the
544 physical memory installed, the remaining memory will be available
545 as "high memory". Accessing high memory is a little more costly
546 than low memory, as it needs to be mapped into the kernel first.
547 Note that increasing the kernel address space limits the range
548 available to user programs, making the address space there
549 tighter. Selecting anything other than the default 3G/1G split
550 will also likely make your kernel incompatible with binary-only
553 If you are not absolutely sure what you are doing, leave this
557 bool "3G/1G user/kernel split"
558 config VMSPLIT_3G_OPT
560 bool "3G/1G user/kernel split (for full 1G low memory)"
562 bool "2G/2G user/kernel split"
564 bool "1G/3G user/kernel split"
569 default 0xB0000000 if VMSPLIT_3G_OPT
570 default 0x78000000 if VMSPLIT_2G
571 default 0x40000000 if VMSPLIT_1G
576 depends on HIGHMEM64G || HIGHMEM4G
581 depends on HIGHMEM64G
583 select RESOURCES_64BIT
585 # Common NUMA Features
587 bool "Numa Memory Allocation and Scheduler Support"
588 depends on SMP && HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT || X86_GENERICARCH) && ACPI)
590 default y if (X86_NUMAQ || X86_SUMMIT)
592 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
593 depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)
597 default "4" if X86_NUMAQ
599 depends on NEED_MULTIPLE_NODES
601 config HAVE_ARCH_BOOTMEM_NODE
606 config ARCH_HAVE_MEMORY_PRESENT
608 depends on DISCONTIGMEM
611 config NEED_NODE_MEMMAP_SIZE
613 depends on DISCONTIGMEM || SPARSEMEM
616 config HAVE_ARCH_ALLOC_REMAP
621 config ARCH_FLATMEM_ENABLE
623 depends on (ARCH_SELECT_MEMORY_MODEL && X86_PC)
625 config ARCH_DISCONTIGMEM_ENABLE
629 config ARCH_DISCONTIGMEM_DEFAULT
633 config ARCH_SPARSEMEM_ENABLE
635 depends on (NUMA || (X86_PC && EXPERIMENTAL))
636 select SPARSEMEM_STATIC
638 config ARCH_SELECT_MEMORY_MODEL
640 depends on ARCH_SPARSEMEM_ENABLE
642 config ARCH_POPULATES_NODE_MAP
648 bool "Allocate 3rd-level pagetables from highmem"
649 depends on HIGHMEM4G || HIGHMEM64G
651 The VM uses one page table entry for each page of physical memory.
652 For systems with a lot of RAM, this can be wasteful of precious
653 low memory. Setting this option will put user-space page table
654 entries in high memory.
656 config MATH_EMULATION
657 bool "Math emulation"
659 Linux can emulate a math coprocessor (used for floating point
660 operations) if you don't have one. 486DX and Pentium processors have
661 a math coprocessor built in, 486SX and 386 do not, unless you added
662 a 487DX or 387, respectively. (The messages during boot time can
663 give you some hints here ["man dmesg"].) Everyone needs either a
664 coprocessor or this emulation.
666 If you don't have a math coprocessor, you need to say Y here; if you
667 say Y here even though you have a coprocessor, the coprocessor will
668 be used nevertheless. (This behavior can be changed with the kernel
669 command line option "no387", which comes handy if your coprocessor
670 is broken. Try "man bootparam" or see the documentation of your boot
671 loader (lilo or loadlin) about how to pass options to the kernel at
672 boot time.) This means that it is a good idea to say Y here if you
673 intend to use this kernel on different machines.
675 More information about the internals of the Linux math coprocessor
676 emulation can be found in <file:arch/i386/math-emu/README>.
678 If you are not sure, say Y; apart from resulting in a 66 KB bigger
679 kernel, it won't hurt.
682 bool "MTRR (Memory Type Range Register) support"
684 On Intel P6 family processors (Pentium Pro, Pentium II and later)
685 the Memory Type Range Registers (MTRRs) may be used to control
686 processor access to memory ranges. This is most useful if you have
687 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
688 allows bus write transfers to be combined into a larger transfer
689 before bursting over the PCI/AGP bus. This can increase performance
690 of image write operations 2.5 times or more. Saying Y here creates a
691 /proc/mtrr file which may be used to manipulate your processor's
692 MTRRs. Typically the X server should use this.
694 This code has a reasonably generic interface so that similar
695 control registers on other processors can be easily supported
698 The Cyrix 6x86, 6x86MX and M II processors have Address Range
699 Registers (ARRs) which provide a similar functionality to MTRRs. For
700 these, the ARRs are used to emulate the MTRRs.
701 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
702 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
703 write-combining. All of these processors are supported by this code
704 and it makes sense to say Y here if you have one of them.
706 Saying Y here also fixes a problem with buggy SMP BIOSes which only
707 set the MTRRs for the boot CPU and not for the secondary CPUs. This
708 can lead to all sorts of problems, so it's good to say Y here.
710 You can safely say Y even if your machine doesn't have MTRRs, you'll
711 just add about 9 KB to your kernel.
713 See <file:Documentation/mtrr.txt> for more information.
716 bool "Boot from EFI support"
720 This enables the kernel to boot on EFI platforms using
721 system configuration information passed to it from the firmware.
722 This also enables the kernel to use any EFI runtime services that are
723 available (such as the EFI variable services).
725 This option is only useful on systems that have EFI firmware
726 and will result in a kernel image that is ~8k larger. In addition,
727 you must use the latest ELILO loader available at
728 <http://elilo.sourceforge.net> in order to take advantage of
729 kernel initialization using EFI information (neither GRUB nor LILO know
730 anything about EFI). However, even with this option, the resultant
731 kernel should continue to boot on existing non-EFI platforms.
734 bool "Enable kernel irq balancing"
735 depends on SMP && X86_IO_APIC
738 The default yes will allow the kernel to do irq load balancing.
739 Saying no will keep the kernel from doing irq load balancing.
741 # turning this on wastes a bunch of space.
742 # Summit needs it only when NUMA is on
745 depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
749 bool "Enable seccomp to safely compute untrusted bytecode"
753 This kernel feature is useful for number crunching applications
754 that may need to compute untrusted bytecode during their
755 execution. By using pipes or other transports made available to
756 the process as file descriptors supporting the read/write
757 syscalls, it's possible to isolate those applications in
758 their own address space using seccomp. Once seccomp is
759 enabled via /proc/<pid>/seccomp, it cannot be disabled
760 and the task is only allowed to execute a few safe syscalls
761 defined by each seccomp mode.
763 If unsure, say Y. Only embedded should say N here.
765 source kernel/Kconfig.hz
768 bool "kexec system call"
770 kexec is a system call that implements the ability to shutdown your
771 current kernel, and to start another kernel. It is like a reboot
772 but it is independent of the system firmware. And like a reboot
773 you can start any kernel with it, not just Linux.
775 The name comes from the similarity to the exec system call.
777 It is an ongoing process to be certain the hardware in a machine
778 is properly shutdown, so do not be surprised if this code does not
779 initially work for you. It may help to enable device hotplugging
780 support. As of this writing the exact hardware interface is
781 strongly in flux, so no good recommendation can be made.
784 bool "kernel crash dumps (EXPERIMENTAL)"
785 depends on EXPERIMENTAL
788 Generate crash dump after being started by kexec.
789 This should be normally only set in special crash dump kernels
790 which are loaded in the main kernel with kexec-tools into
791 a specially reserved region and then later executed after
792 a crash by kdump/kexec. The crash dump kernel must be compiled
793 to a memory address not used by the main kernel or BIOS using
795 For more details see Documentation/kdump/kdump.txt
797 config PHYSICAL_START
798 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
801 This gives the physical address where the kernel is loaded.
803 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
804 bzImage will decompress itself to above physical address and
805 run from there. Otherwise, bzImage will run from the address where
806 it has been loaded by the boot loader and will ignore above physical
809 In normal kdump cases one does not have to set/change this option
810 as now bzImage can be compiled as a completely relocatable image
811 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
812 address. This option is mainly useful for the folks who don't want
813 to use a bzImage for capturing the crash dump and want to use a
814 vmlinux instead. vmlinux is not relocatable hence a kernel needs
815 to be specifically compiled to run from a specific memory area
816 (normally a reserved region) and this option comes handy.
818 So if you are using bzImage for capturing the crash dump, leave
819 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
820 Otherwise if you plan to use vmlinux for capturing the crash dump
821 change this value to start of the reserved region (Typically 16MB
822 0x1000000). In other words, it can be set based on the "X" value as
823 specified in the "crashkernel=YM@XM" command line boot parameter
824 passed to the panic-ed kernel. Typically this parameter is set as
825 crashkernel=64M@16M. Please take a look at
826 Documentation/kdump/kdump.txt for more details about crash dumps.
828 Usage of bzImage for capturing the crash dump is recommended as
829 one does not have to build two kernels. Same kernel can be used
830 as production kernel and capture kernel. Above option should have
831 gone away after relocatable bzImage support is introduced. But it
832 is present because there are users out there who continue to use
833 vmlinux for dump capture. This option should go away down the
836 Don't change this unless you know what you are doing.
839 bool "Build a relocatable kernel(EXPERIMENTAL)"
840 depends on EXPERIMENTAL
842 This build a kernel image that retains relocation information
843 so it can be loaded someplace besides the default 1MB.
844 The relocations tend to the kernel binary about 10% larger,
845 but are discarded at runtime.
847 One use is for the kexec on panic case where the recovery kernel
848 must live at a different physical address than the primary
851 config PHYSICAL_ALIGN
852 hex "Alignment value to which kernel should be aligned"
854 range 0x2000 0x400000
856 This value puts the alignment restrictions on physical address
857 where kernel is loaded and run from. Kernel is compiled for an
858 address which meets above alignment restriction.
860 If bootloader loads the kernel at a non-aligned address and
861 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
862 address aligned to above value and run from there.
864 If bootloader loads the kernel at a non-aligned address and
865 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
866 load address and decompress itself to the address it has been
867 compiled for and run from there. The address for which kernel is
868 compiled already meets above alignment restrictions. Hence the
869 end result is that kernel runs from a physical address meeting
870 above alignment restrictions.
872 Don't change this unless you know what you are doing.
875 bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
876 depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
878 Say Y here to experiment with turning CPUs off and on, and to
879 enable suspend on SMP systems. CPUs can be controlled through
880 /sys/devices/system/cpu.
883 bool "Compat VDSO support"
887 Map the VDSO to the predictable old-style address too.
889 Say N here if you are running a sufficiently recent glibc
890 version (2.3.3 or later), to remove the high-mapped
891 VDSO mapping and to exclusively use the randomized VDSO.
897 config ARCH_ENABLE_MEMORY_HOTPLUG
901 menu "Power management options (ACPI, APM)"
902 depends on !X86_VOYAGER
904 source kernel/power/Kconfig
906 source "drivers/acpi/Kconfig"
908 menu "APM (Advanced Power Management) BIOS Support"
909 depends on PM && !X86_VISWS
912 tristate "APM (Advanced Power Management) BIOS support"
915 APM is a BIOS specification for saving power using several different
916 techniques. This is mostly useful for battery powered laptops with
917 APM compliant BIOSes. If you say Y here, the system time will be
918 reset after a RESUME operation, the /proc/apm device will provide
919 battery status information, and user-space programs will receive
920 notification of APM "events" (e.g. battery status change).
922 If you select "Y" here, you can disable actual use of the APM
923 BIOS by passing the "apm=off" option to the kernel at boot time.
925 Note that the APM support is almost completely disabled for
926 machines with more than one CPU.
928 In order to use APM, you will need supporting software. For location
929 and more information, read <file:Documentation/pm.txt> and the
930 Battery Powered Linux mini-HOWTO, available from
931 <http://www.tldp.org/docs.html#howto>.
933 This driver does not spin down disk drives (see the hdparm(8)
934 manpage ("man 8 hdparm") for that), and it doesn't turn off
935 VESA-compliant "green" monitors.
937 This driver does not support the TI 4000M TravelMate and the ACER
938 486/DX4/75 because they don't have compliant BIOSes. Many "green"
939 desktop machines also don't have compliant BIOSes, and this driver
940 may cause those machines to panic during the boot phase.
942 Generally, if you don't have a battery in your machine, there isn't
943 much point in using this driver and you should say N. If you get
944 random kernel OOPSes or reboots that don't seem to be related to
945 anything, try disabling/enabling this option (or disabling/enabling
948 Some other things you should try when experiencing seemingly random,
951 1) make sure that you have enough swap space and that it is
953 2) pass the "no-hlt" option to the kernel
954 3) switch on floating point emulation in the kernel and pass
955 the "no387" option to the kernel
956 4) pass the "floppy=nodma" option to the kernel
957 5) pass the "mem=4M" option to the kernel (thereby disabling
958 all but the first 4 MB of RAM)
959 6) make sure that the CPU is not over clocked.
960 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
961 8) disable the cache from your BIOS settings
962 9) install a fan for the video card or exchange video RAM
963 10) install a better fan for the CPU
964 11) exchange RAM chips
965 12) exchange the motherboard.
967 To compile this driver as a module, choose M here: the
968 module will be called apm.
970 config APM_IGNORE_USER_SUSPEND
971 bool "Ignore USER SUSPEND"
974 This option will ignore USER SUSPEND requests. On machines with a
975 compliant APM BIOS, you want to say N. However, on the NEC Versa M
976 series notebooks, it is necessary to say Y because of a BIOS bug.
979 bool "Enable PM at boot time"
982 Enable APM features at boot time. From page 36 of the APM BIOS
983 specification: "When disabled, the APM BIOS does not automatically
984 power manage devices, enter the Standby State, enter the Suspend
985 State, or take power saving steps in response to CPU Idle calls."
986 This driver will make CPU Idle calls when Linux is idle (unless this
987 feature is turned off -- see "Do CPU IDLE calls", below). This
988 should always save battery power, but more complicated APM features
989 will be dependent on your BIOS implementation. You may need to turn
990 this option off if your computer hangs at boot time when using APM
991 support, or if it beeps continuously instead of suspending. Turn
992 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
993 T400CDT. This is off by default since most machines do fine without
997 bool "Make CPU Idle calls when idle"
1000 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1001 On some machines, this can activate improved power savings, such as
1002 a slowed CPU clock rate, when the machine is idle. These idle calls
1003 are made after the idle loop has run for some length of time (e.g.,
1004 333 mS). On some machines, this will cause a hang at boot time or
1005 whenever the CPU becomes idle. (On machines with more than one CPU,
1006 this option does nothing.)
1008 config APM_DISPLAY_BLANK
1009 bool "Enable console blanking using APM"
1012 Enable console blanking using the APM. Some laptops can use this to
1013 turn off the LCD backlight when the screen blanker of the Linux
1014 virtual console blanks the screen. Note that this is only used by
1015 the virtual console screen blanker, and won't turn off the backlight
1016 when using the X Window system. This also doesn't have anything to
1017 do with your VESA-compliant power-saving monitor. Further, this
1018 option doesn't work for all laptops -- it might not turn off your
1019 backlight at all, or it might print a lot of errors to the console,
1020 especially if you are using gpm.
1022 config APM_RTC_IS_GMT
1023 bool "RTC stores time in GMT"
1026 Say Y here if your RTC (Real Time Clock a.k.a. hardware clock)
1027 stores the time in GMT (Greenwich Mean Time). Say N if your RTC
1030 It is in fact recommended to store GMT in your RTC, because then you
1031 don't have to worry about daylight savings time changes. The only
1032 reason not to use GMT in your RTC is if you also run a broken OS
1033 that doesn't understand GMT.
1035 config APM_ALLOW_INTS
1036 bool "Allow interrupts during APM BIOS calls"
1039 Normally we disable external interrupts while we are making calls to
1040 the APM BIOS as a measure to lessen the effects of a badly behaving
1041 BIOS implementation. The BIOS should reenable interrupts if it
1042 needs to. Unfortunately, some BIOSes do not -- especially those in
1043 many of the newer IBM Thinkpads. If you experience hangs when you
1044 suspend, try setting this to Y. Otherwise, say N.
1046 config APM_REAL_MODE_POWER_OFF
1047 bool "Use real mode APM BIOS call to power off"
1050 Use real mode APM BIOS calls to switch off the computer. This is
1051 a work-around for a number of buggy BIOSes. Switch this option on if
1052 your computer crashes instead of powering off properly.
1056 source "arch/i386/kernel/cpu/cpufreq/Kconfig"
1060 menu "Bus options (PCI, PCMCIA, EISA, MCA, ISA)"
1063 bool "PCI support" if !X86_VISWS
1064 depends on !X86_VOYAGER
1065 default y if X86_VISWS
1067 Find out whether you have a PCI motherboard. PCI is the name of a
1068 bus system, i.e. the way the CPU talks to the other stuff inside
1069 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1070 VESA. If you have PCI, say Y, otherwise N.
1072 The PCI-HOWTO, available from
1073 <http://www.tldp.org/docs.html#howto>, contains valuable
1074 information about which PCI hardware does work under Linux and which
1078 prompt "PCI access mode"
1079 depends on PCI && !X86_VISWS
1082 On PCI systems, the BIOS can be used to detect the PCI devices and
1083 determine their configuration. However, some old PCI motherboards
1084 have BIOS bugs and may crash if this is done. Also, some embedded
1085 PCI-based systems don't have any BIOS at all. Linux can also try to
1086 detect the PCI hardware directly without using the BIOS.
1088 With this option, you can specify how Linux should detect the
1089 PCI devices. If you choose "BIOS", the BIOS will be used,
1090 if you choose "Direct", the BIOS won't be used, and if you
1091 choose "MMConfig", then PCI Express MMCONFIG will be used.
1092 If you choose "Any", the kernel will try MMCONFIG, then the
1093 direct access method and falls back to the BIOS if that doesn't
1094 work. If unsure, go with the default, which is "Any".
1099 config PCI_GOMMCONFIG
1112 depends on !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1117 depends on PCI && ((PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1122 depends on PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1125 source "drivers/pci/pcie/Kconfig"
1127 source "drivers/pci/Kconfig"
1135 depends on !(X86_VOYAGER || X86_VISWS)
1137 Find out whether you have ISA slots on your motherboard. ISA is the
1138 name of a bus system, i.e. the way the CPU talks to the other stuff
1139 inside your box. Other bus systems are PCI, EISA, MicroChannel
1140 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1141 newer boards don't support it. If you have ISA, say Y, otherwise N.
1147 The Extended Industry Standard Architecture (EISA) bus was
1148 developed as an open alternative to the IBM MicroChannel bus.
1150 The EISA bus provided some of the features of the IBM MicroChannel
1151 bus while maintaining backward compatibility with cards made for
1152 the older ISA bus. The EISA bus saw limited use between 1988 and
1153 1995 when it was made obsolete by the PCI bus.
1155 Say Y here if you are building a kernel for an EISA-based machine.
1159 source "drivers/eisa/Kconfig"
1162 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1163 default y if X86_VOYAGER
1165 MicroChannel Architecture is found in some IBM PS/2 machines and
1166 laptops. It is a bus system similar to PCI or ISA. See
1167 <file:Documentation/mca.txt> (and especially the web page given
1168 there) before attempting to build an MCA bus kernel.
1170 source "drivers/mca/Kconfig"
1173 tristate "NatSemi SCx200 support"
1174 depends on !X86_VOYAGER
1176 This provides basic support for National Semiconductor's
1177 (now AMD's) Geode processors. The driver probes for the
1178 PCI-IDs of several on-chip devices, so its a good dependency
1179 for other scx200_* drivers.
1181 If compiled as a module, the driver is named scx200.
1183 config SCx200HR_TIMER
1184 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1185 depends on SCx200 && GENERIC_TIME
1188 This driver provides a clocksource built upon the on-chip
1189 27MHz high-resolution timer. Its also a workaround for
1190 NSC Geode SC-1100's buggy TSC, which loses time when the
1191 processor goes idle (as is done by the scheduler). The
1192 other workaround is idle=poll boot option.
1196 depends on AGP_AMD64
1198 source "drivers/pcmcia/Kconfig"
1200 source "drivers/pci/hotplug/Kconfig"
1204 menu "Executable file formats"
1206 source "fs/Kconfig.binfmt"
1210 source "net/Kconfig"
1212 source "drivers/Kconfig"
1216 menu "Instrumentation Support"
1217 depends on EXPERIMENTAL
1219 source "arch/i386/oprofile/Kconfig"
1222 bool "Kprobes (EXPERIMENTAL)"
1223 depends on KALLSYMS && EXPERIMENTAL && MODULES
1225 Kprobes allows you to trap at almost any kernel address and
1226 execute a callback function. register_kprobe() establishes
1227 a probepoint and specifies the callback. Kprobes is useful
1228 for kernel debugging, non-intrusive instrumentation and testing.
1229 If in doubt, say "N".
1232 source "arch/i386/Kconfig.debug"
1234 source "security/Kconfig"
1236 source "crypto/Kconfig"
1238 source "lib/Kconfig"
1241 # Use the generic interrupt handling code in kernel/irq/:
1243 config GENERIC_HARDIRQS
1247 config GENERIC_IRQ_PROBE
1251 config GENERIC_PENDING_IRQ
1253 depends on GENERIC_HARDIRQS && SMP
1258 depends on SMP && !X86_VOYAGER
1263 depends on SMP && !(X86_VISWS || X86_VOYAGER)
1266 config X86_BIOS_REBOOT
1268 depends on !(X86_VISWS || X86_VOYAGER)
1271 config X86_TRAMPOLINE
1273 depends on X86_SMP || (X86_VOYAGER && SMP)
1285 Switches the regular HZ timer off when the system is going idle.
1286 This helps a hypervisor detect that the Linux system is idle,
1287 reducing the overhead of idle systems.