2 mainmenu "Linux Kernel Configuration for x86"
6 bool "64-bit kernel" if ARCH = "x86"
7 default ARCH = "x86_64"
9 Say yes to build a 64-bit kernel - formerly known as x86_64
10 Say no to build a 32-bit kernel - formerly known as i386
24 config GENERIC_LOCKBREAK
30 config GENERIC_CMOS_UPDATE
33 config CLOCKSOURCE_WATCHDOG
36 config GENERIC_CLOCKEVENTS
39 config GENERIC_CLOCKEVENTS_BROADCAST
41 depends on X86_64 || (X86_32 && X86_LOCAL_APIC)
43 config LOCKDEP_SUPPORT
46 config STACKTRACE_SUPPORT
49 config HAVE_LATENCYTOP_SUPPORT
52 config SEMAPHORE_SLEEPERS
67 config GENERIC_ISA_DMA
77 config GENERIC_HWEIGHT
83 config ARCH_MAY_HAVE_PC_FDC
89 config RWSEM_GENERIC_SPINLOCK
92 config RWSEM_XCHGADD_ALGORITHM
95 config ARCH_HAS_ILOG2_U32
98 config ARCH_HAS_ILOG2_U64
101 config GENERIC_CALIBRATE_DELAY
104 config GENERIC_TIME_VSYSCALL
108 config HAVE_SETUP_PER_CPU_AREA
113 config ARCH_HIBERNATION_POSSIBLE
115 depends on !SMP || !X86_VOYAGER
117 config ARCH_SUSPEND_POSSIBLE
119 depends on !X86_VOYAGER
125 config ARCH_POPULATES_NODE_MAP
132 # Use the generic interrupt handling code in kernel/irq/:
133 config GENERIC_HARDIRQS
137 config GENERIC_IRQ_PROBE
141 config GENERIC_PENDING_IRQ
143 depends on GENERIC_HARDIRQS && SMP
148 depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)
153 depends on X86_32 && SMP
157 depends on X86_64 && SMP
162 depends on (X86_32 && !(X86_VISWS || X86_VOYAGER)) || (X86_64 && !MK8)
165 config X86_BIOS_REBOOT
167 depends on X86_32 && !(X86_VISWS || X86_VOYAGER)
170 config X86_TRAMPOLINE
172 depends on X86_SMP || (X86_VOYAGER && SMP)
177 source "init/Kconfig"
179 menu "Processor type and features"
181 source "kernel/time/Kconfig"
184 bool "Symmetric multi-processing support"
186 This enables support for systems with more than one CPU. If you have
187 a system with only one CPU, like most personal computers, say N. If
188 you have a system with more than one CPU, say Y.
190 If you say N here, the kernel will run on single and multiprocessor
191 machines, but will use only one CPU of a multiprocessor machine. If
192 you say Y here, the kernel will run on many, but not all,
193 singleprocessor machines. On a singleprocessor machine, the kernel
194 will run faster if you say N here.
196 Note that if you say Y here and choose architecture "586" or
197 "Pentium" under "Processor family", the kernel will not work on 486
198 architectures. Similarly, multiprocessor kernels for the "PPro"
199 architecture may not work on all Pentium based boards.
201 People using multiprocessor machines who say Y here should also say
202 Y to "Enhanced Real Time Clock Support", below. The "Advanced Power
203 Management" code will be disabled if you say Y here.
205 See also <file:Documentation/i386/IO-APIC.txt>,
206 <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
207 <http://www.tldp.org/docs.html#howto>.
209 If you don't know what to do here, say N.
212 prompt "Subarchitecture Type"
218 Choose this option if your computer is a standard PC or compatible.
224 Select this for an AMD Elan processor.
226 Do not use this option for K6/Athlon/Opteron processors!
228 If unsure, choose "PC-compatible" instead.
233 select SMP if !BROKEN
235 Voyager is an MCA-based 32-way capable SMP architecture proprietary
236 to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
240 If you do not specifically know you have a Voyager based machine,
241 say N here, otherwise the kernel you build will not be bootable.
244 bool "NUMAQ (IBM/Sequent)"
249 This option is used for getting Linux to run on a (IBM/Sequent) NUMA
250 multiquad box. This changes the way that processors are bootstrapped,
251 and uses Clustered Logical APIC addressing mode instead of Flat Logical.
252 You will need a new lynxer.elf file to flash your firmware with - send
253 email to <Martin.Bligh@us.ibm.com>.
256 bool "Summit/EXA (IBM x440)"
257 depends on X86_32 && SMP
259 This option is needed for IBM systems that use the Summit/EXA chipset.
260 In particular, it is needed for the x440.
262 If you don't have one of these computers, you should say N here.
263 If you want to build a NUMA kernel, you must select ACPI.
266 bool "Support for other sub-arch SMP systems with more than 8 CPUs"
267 depends on X86_32 && SMP
269 This option is needed for the systems that have more than 8 CPUs
270 and if the system is not of any sub-arch type above.
272 If you don't have such a system, you should say N here.
275 bool "SGI 320/540 (Visual Workstation)"
278 The SGI Visual Workstation series is an IA32-based workstation
279 based on SGI systems chips with some legacy PC hardware attached.
281 Say Y here to create a kernel to run on the SGI 320 or 540.
283 A kernel compiled for the Visual Workstation will not run on PCs
284 and vice versa. See <file:Documentation/sgi-visws.txt> for details.
286 config X86_GENERICARCH
287 bool "Generic architecture (Summit, bigsmp, ES7000, default)"
290 This option compiles in the Summit, bigsmp, ES7000, default subarchitectures.
291 It is intended for a generic binary kernel.
292 If you want a NUMA kernel, select ACPI. We need SRAT for NUMA.
295 bool "Support for Unisys ES7000 IA32 series"
296 depends on X86_32 && SMP
298 Support for Unisys ES7000 systems. Say 'Y' here if this kernel is
299 supposed to run on an IA32-based Unisys ES7000 system.
300 Only choose this option if you have such a system, otherwise you
304 bool "RDC R-321x SoC"
307 select X86_REBOOTFIXUPS
312 This option is needed for RDC R-321x system-on-chip, also known
314 If you don't have one of these chips, you should say N here.
317 bool "Support for ScaleMP vSMP"
318 depends on X86_64 && PCI
320 Support for ScaleMP vSMP systems. Say 'Y' here if this kernel is
321 supposed to run on these EM64T-based machines. Only choose this option
322 if you have one of these machines.
326 config SCHED_NO_NO_OMIT_FRAME_POINTER
328 prompt "Single-depth WCHAN output"
331 Calculate simpler /proc/<PID>/wchan values. If this option
332 is disabled then wchan values will recurse back to the
333 caller function. This provides more accurate wchan values,
334 at the expense of slightly more scheduling overhead.
336 If in doubt, say "Y".
338 menuconfig PARAVIRT_GUEST
339 bool "Paravirtualized guest support"
341 Say Y here to get to see options related to running Linux under
342 various hypervisors. This option alone does not add any kernel code.
344 If you say N, all options in this submenu will be skipped and disabled.
348 source "arch/x86/xen/Kconfig"
351 bool "VMI Guest support"
354 depends on !(X86_VISWS || X86_VOYAGER)
356 VMI provides a paravirtualized interface to the VMware ESX server
357 (it could be used by other hypervisors in theory too, but is not
358 at the moment), by linking the kernel to a GPL-ed ROM module
359 provided by the hypervisor.
361 source "arch/x86/lguest/Kconfig"
364 bool "Enable paravirtualization code"
365 depends on !(X86_VISWS || X86_VOYAGER)
367 This changes the kernel so it can modify itself when it is run
368 under a hypervisor, potentially improving performance significantly
369 over full virtualization. However, when run without a hypervisor
370 the kernel is theoretically slower and slightly larger.
376 depends on X86_32 && ACPI && NUMA && (X86_SUMMIT || X86_GENERICARCH)
379 config HAVE_ARCH_PARSE_SRAT
383 config X86_SUMMIT_NUMA
385 depends on X86_32 && NUMA && (X86_SUMMIT || X86_GENERICARCH)
387 config X86_CYCLONE_TIMER
389 depends on X86_32 && X86_SUMMIT || X86_GENERICARCH
391 config ES7000_CLUSTERED_APIC
393 depends on SMP && X86_ES7000 && MPENTIUMIII
395 source "arch/x86/Kconfig.cpu"
399 prompt "HPET Timer Support" if X86_32
401 Use the IA-PC HPET (High Precision Event Timer) to manage
402 time in preference to the PIT and RTC, if a HPET is
404 HPET is the next generation timer replacing legacy 8254s.
405 The HPET provides a stable time base on SMP
406 systems, unlike the TSC, but it is more expensive to access,
407 as it is off-chip. You can find the HPET spec at
408 <http://www.intel.com/hardwaredesign/hpetspec.htm>.
410 You can safely choose Y here. However, HPET will only be
411 activated if the platform and the BIOS support this feature.
412 Otherwise the 8254 will be used for timing services.
414 Choose N to continue using the legacy 8254 timer.
416 config HPET_EMULATE_RTC
418 depends on HPET_TIMER && (RTC=y || RTC=m)
420 # Mark as embedded because too many people got it wrong.
421 # The code disables itself when not needed.
423 bool "GART IOMMU support" if EMBEDDED
427 depends on X86_64 && PCI
429 Support for full DMA access of devices with 32bit memory access only
430 on systems with more than 3GB. This is usually needed for USB,
431 sound, many IDE/SATA chipsets and some other devices.
432 Provides a driver for the AMD Athlon64/Opteron/Turion/Sempron GART
433 based hardware IOMMU and a software bounce buffer based IOMMU used
434 on Intel systems and as fallback.
435 The code is only active when needed (enough memory and limited
436 device) unless CONFIG_IOMMU_DEBUG or iommu=force is specified
440 bool "IBM Calgary IOMMU support"
442 depends on X86_64 && PCI && EXPERIMENTAL
444 Support for hardware IOMMUs in IBM's xSeries x366 and x460
445 systems. Needed to run systems with more than 3GB of memory
446 properly with 32-bit PCI devices that do not support DAC
447 (Double Address Cycle). Calgary also supports bus level
448 isolation, where all DMAs pass through the IOMMU. This
449 prevents them from going anywhere except their intended
450 destination. This catches hard-to-find kernel bugs and
451 mis-behaving drivers and devices that do not use the DMA-API
452 properly to set up their DMA buffers. The IOMMU can be
453 turned off at boot time with the iommu=off parameter.
454 Normally the kernel will make the right choice by itself.
457 config CALGARY_IOMMU_ENABLED_BY_DEFAULT
459 prompt "Should Calgary be enabled by default?"
460 depends on CALGARY_IOMMU
462 Should Calgary be enabled by default? if you choose 'y', Calgary
463 will be used (if it exists). If you choose 'n', Calgary will not be
464 used even if it exists. If you choose 'n' and would like to use
465 Calgary anyway, pass 'iommu=calgary' on the kernel command line.
468 # need this always selected by IOMMU for the VIA workaround
472 Support for software bounce buffers used on x86-64 systems
473 which don't have a hardware IOMMU (e.g. the current generation
474 of Intel's x86-64 CPUs). Using this PCI devices which can only
475 access 32-bits of memory can be used on systems with more than
476 3 GB of memory. If unsure, say Y.
480 int "Maximum number of CPUs (2-255)"
483 default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
486 This allows you to specify the maximum number of CPUs which this
487 kernel will support. The maximum supported value is 255 and the
488 minimum value which makes sense is 2.
490 This is purely to save memory - each supported CPU adds
491 approximately eight kilobytes to the kernel image.
494 bool "SMT (Hyperthreading) scheduler support"
495 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
497 SMT scheduler support improves the CPU scheduler's decision making
498 when dealing with Intel Pentium 4 chips with HyperThreading at a
499 cost of slightly increased overhead in some places. If unsure say
504 prompt "Multi-core scheduler support"
505 depends on (X86_64 && SMP) || (X86_32 && X86_HT)
507 Multi-core scheduler support improves the CPU scheduler's decision
508 making when dealing with multi-core CPU chips at a cost of slightly
509 increased overhead in some places. If unsure say N here.
511 source "kernel/Kconfig.preempt"
514 bool "Local APIC support on uniprocessors"
515 depends on X86_32 && !SMP && !(X86_VISWS || X86_VOYAGER || X86_GENERICARCH)
517 A local APIC (Advanced Programmable Interrupt Controller) is an
518 integrated interrupt controller in the CPU. If you have a single-CPU
519 system which has a processor with a local APIC, you can say Y here to
520 enable and use it. If you say Y here even though your machine doesn't
521 have a local APIC, then the kernel will still run with no slowdown at
522 all. The local APIC supports CPU-generated self-interrupts (timer,
523 performance counters), and the NMI watchdog which detects hard
527 bool "IO-APIC support on uniprocessors"
528 depends on X86_UP_APIC
530 An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
531 SMP-capable replacement for PC-style interrupt controllers. Most
532 SMP systems and many recent uniprocessor systems have one.
534 If you have a single-CPU system with an IO-APIC, you can say Y here
535 to use it. If you say Y here even though your machine doesn't have
536 an IO-APIC, then the kernel will still run with no slowdown at all.
538 config X86_LOCAL_APIC
540 depends on X86_64 || (X86_32 && (X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER) || X86_GENERICARCH))
544 depends on X86_64 || (X86_32 && (X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER)) || X86_GENERICARCH))
546 config X86_VISWS_APIC
548 depends on X86_32 && X86_VISWS
551 bool "Machine Check Exception"
552 depends on !X86_VOYAGER
554 Machine Check Exception support allows the processor to notify the
555 kernel if it detects a problem (e.g. overheating, component failure).
556 The action the kernel takes depends on the severity of the problem,
557 ranging from a warning message on the console, to halting the machine.
558 Your processor must be a Pentium or newer to support this - check the
559 flags in /proc/cpuinfo for mce. Note that some older Pentium systems
560 have a design flaw which leads to false MCE events - hence MCE is
561 disabled on all P5 processors, unless explicitly enabled with "mce"
562 as a boot argument. Similarly, if MCE is built in and creates a
563 problem on some new non-standard machine, you can boot with "nomce"
564 to disable it. MCE support simply ignores non-MCE processors like
565 the 386 and 486, so nearly everyone can say Y here.
569 prompt "Intel MCE features"
570 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
572 Additional support for intel specific MCE features such as
577 prompt "AMD MCE features"
578 depends on X86_64 && X86_MCE && X86_LOCAL_APIC
580 Additional support for AMD specific MCE features such as
581 the DRAM Error Threshold.
583 config X86_MCE_NONFATAL
584 tristate "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
585 depends on X86_32 && X86_MCE
587 Enabling this feature starts a timer that triggers every 5 seconds which
588 will look at the machine check registers to see if anything happened.
589 Non-fatal problems automatically get corrected (but still logged).
590 Disable this if you don't want to see these messages.
591 Seeing the messages this option prints out may be indicative of dying
592 or out-of-spec (ie, overclocked) hardware.
593 This option only does something on certain CPUs.
594 (AMD Athlon/Duron and Intel Pentium 4)
596 config X86_MCE_P4THERMAL
597 bool "check for P4 thermal throttling interrupt."
598 depends on X86_32 && X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
600 Enabling this feature will cause a message to be printed when the P4
601 enters thermal throttling.
604 bool "Enable VM86 support" if EMBEDDED
608 This option is required by programs like DOSEMU to run 16-bit legacy
609 code on X86 processors. It also may be needed by software like
610 XFree86 to initialize some video cards via BIOS. Disabling this
611 option saves about 6k.
614 tristate "Toshiba Laptop support"
617 This adds a driver to safely access the System Management Mode of
618 the CPU on Toshiba portables with a genuine Toshiba BIOS. It does
619 not work on models with a Phoenix BIOS. The System Management Mode
620 is used to set the BIOS and power saving options on Toshiba portables.
622 For information on utilities to make use of this driver see the
623 Toshiba Linux utilities web site at:
624 <http://www.buzzard.org.uk/toshiba/>.
626 Say Y if you intend to run this kernel on a Toshiba portable.
630 tristate "Dell laptop support"
633 This adds a driver to safely access the System Management Mode
634 of the CPU on the Dell Inspiron 8000. The System Management Mode
635 is used to read cpu temperature and cooling fan status and to
636 control the fans on the I8K portables.
638 This driver has been tested only on the Inspiron 8000 but it may
639 also work with other Dell laptops. You can force loading on other
640 models by passing the parameter `force=1' to the module. Use at
643 For information on utilities to make use of this driver see the
644 I8K Linux utilities web site at:
645 <http://people.debian.org/~dz/i8k/>
647 Say Y if you intend to run this kernel on a Dell Inspiron 8000.
650 config X86_REBOOTFIXUPS
652 prompt "Enable X86 board specific fixups for reboot"
653 depends on X86_32 && X86
655 This enables chipset and/or board specific fixups to be done
656 in order to get reboot to work correctly. This is only needed on
657 some combinations of hardware and BIOS. The symptom, for which
658 this config is intended, is when reboot ends with a stalled/hung
661 Currently, the only fixup is for the Geode machines using
662 CS5530A and CS5536 chipsets and the RDC R-321x SoC.
664 Say Y if you want to enable the fixup. Currently, it's safe to
665 enable this option even if you don't need it.
669 tristate "/dev/cpu/microcode - Intel IA32 CPU microcode support"
672 If you say Y here, you will be able to update the microcode on
673 Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II,
674 Pentium III, Pentium 4, Xeon etc. You will obviously need the
675 actual microcode binary data itself which is not shipped with the
678 For latest news and information on obtaining all the required
679 ingredients for this driver, check:
680 <http://www.urbanmyth.org/microcode/>.
682 To compile this driver as a module, choose M here: the
683 module will be called microcode.
685 config MICROCODE_OLD_INTERFACE
690 tristate "/dev/cpu/*/msr - Model-specific register support"
692 This device gives privileged processes access to the x86
693 Model-Specific Registers (MSRs). It is a character device with
694 major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr.
695 MSR accesses are directed to a specific CPU on multi-processor
699 tristate "/dev/cpu/*/cpuid - CPU information support"
701 This device gives processes access to the x86 CPUID instruction to
702 be executed on a specific processor. It is a character device
703 with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to
707 prompt "High Memory Support"
708 default HIGHMEM4G if !X86_NUMAQ
709 default HIGHMEM64G if X86_NUMAQ
714 depends on !X86_NUMAQ
716 Linux can use up to 64 Gigabytes of physical memory on x86 systems.
717 However, the address space of 32-bit x86 processors is only 4
718 Gigabytes large. That means that, if you have a large amount of
719 physical memory, not all of it can be "permanently mapped" by the
720 kernel. The physical memory that's not permanently mapped is called
723 If you are compiling a kernel which will never run on a machine with
724 more than 1 Gigabyte total physical RAM, answer "off" here (default
725 choice and suitable for most users). This will result in a "3GB/1GB"
726 split: 3GB are mapped so that each process sees a 3GB virtual memory
727 space and the remaining part of the 4GB virtual memory space is used
728 by the kernel to permanently map as much physical memory as
731 If the machine has between 1 and 4 Gigabytes physical RAM, then
734 If more than 4 Gigabytes is used then answer "64GB" here. This
735 selection turns Intel PAE (Physical Address Extension) mode on.
736 PAE implements 3-level paging on IA32 processors. PAE is fully
737 supported by Linux, PAE mode is implemented on all recent Intel
738 processors (Pentium Pro and better). NOTE: If you say "64GB" here,
739 then the kernel will not boot on CPUs that don't support PAE!
741 The actual amount of total physical memory will either be
742 auto detected or can be forced by using a kernel command line option
743 such as "mem=256M". (Try "man bootparam" or see the documentation of
744 your boot loader (lilo or loadlin) about how to pass options to the
745 kernel at boot time.)
747 If unsure, say "off".
751 depends on !X86_NUMAQ
753 Select this if you have a 32-bit processor and between 1 and 4
754 gigabytes of physical RAM.
758 depends on !M386 && !M486
761 Select this if you have a 32-bit processor and more than 4
762 gigabytes of physical RAM.
767 depends on EXPERIMENTAL
768 prompt "Memory split" if EMBEDDED
772 Select the desired split between kernel and user memory.
774 If the address range available to the kernel is less than the
775 physical memory installed, the remaining memory will be available
776 as "high memory". Accessing high memory is a little more costly
777 than low memory, as it needs to be mapped into the kernel first.
778 Note that increasing the kernel address space limits the range
779 available to user programs, making the address space there
780 tighter. Selecting anything other than the default 3G/1G split
781 will also likely make your kernel incompatible with binary-only
784 If you are not absolutely sure what you are doing, leave this
788 bool "3G/1G user/kernel split"
789 config VMSPLIT_3G_OPT
791 bool "3G/1G user/kernel split (for full 1G low memory)"
793 bool "2G/2G user/kernel split"
794 config VMSPLIT_2G_OPT
796 bool "2G/2G user/kernel split (for full 2G low memory)"
798 bool "1G/3G user/kernel split"
803 default 0xB0000000 if VMSPLIT_3G_OPT
804 default 0x80000000 if VMSPLIT_2G
805 default 0x78000000 if VMSPLIT_2G_OPT
806 default 0x40000000 if VMSPLIT_1G
812 depends on X86_32 && (HIGHMEM64G || HIGHMEM4G)
816 prompt "PAE (Physical Address Extension) Support"
817 depends on X86_32 && !HIGHMEM4G
818 select RESOURCES_64BIT
820 PAE is required for NX support, and furthermore enables
821 larger swapspace support for non-overcommit purposes. It
822 has the cost of more pagetable lookup overhead, and also
823 consumes more pagetable space per process.
825 # Common NUMA Features
827 bool "Numa Memory Allocation and Scheduler Support (EXPERIMENTAL)"
829 depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || (X86_SUMMIT || X86_GENERICARCH) && ACPI) && EXPERIMENTAL)
831 default y if (X86_NUMAQ || X86_SUMMIT)
833 Enable NUMA (Non Uniform Memory Access) support.
834 The kernel will try to allocate memory used by a CPU on the
835 local memory controller of the CPU and add some more
836 NUMA awareness to the kernel.
838 For i386 this is currently highly experimental and should be only
839 used for kernel development. It might also cause boot failures.
840 For x86_64 this is recommended on all multiprocessor Opteron systems.
841 If the system is EM64T, you should say N unless your system is
844 comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
845 depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)
849 prompt "Old style AMD Opteron NUMA detection"
850 depends on X86_64 && NUMA && PCI
852 Enable K8 NUMA node topology detection. You should say Y here if
853 you have a multi processor AMD K8 system. This uses an old
854 method to read the NUMA configuration directly from the builtin
855 Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
856 instead, which also takes priority if both are compiled in.
858 config X86_64_ACPI_NUMA
860 prompt "ACPI NUMA detection"
861 depends on X86_64 && NUMA && ACPI && PCI
864 Enable ACPI SRAT based node topology detection.
867 bool "NUMA emulation"
868 depends on X86_64 && NUMA
870 Enable NUMA emulation. A flat machine will be split
871 into virtual nodes when booted with "numa=fake=N", where N is the
872 number of nodes. This is only useful for debugging.
877 default "6" if X86_64
878 default "4" if X86_NUMAQ
880 depends on NEED_MULTIPLE_NODES
882 config HAVE_ARCH_BOOTMEM_NODE
884 depends on X86_32 && NUMA
886 config ARCH_HAVE_MEMORY_PRESENT
888 depends on X86_32 && DISCONTIGMEM
890 config NEED_NODE_MEMMAP_SIZE
892 depends on X86_32 && (DISCONTIGMEM || SPARSEMEM)
894 config HAVE_ARCH_ALLOC_REMAP
896 depends on X86_32 && NUMA
898 config ARCH_FLATMEM_ENABLE
900 depends on X86_32 && ARCH_SELECT_MEMORY_MODEL && X86_PC && !NUMA
902 config ARCH_DISCONTIGMEM_ENABLE
904 depends on NUMA && X86_32
906 config ARCH_DISCONTIGMEM_DEFAULT
908 depends on NUMA && X86_32
910 config ARCH_SPARSEMEM_DEFAULT
914 config ARCH_SPARSEMEM_ENABLE
916 depends on X86_64 || NUMA || (EXPERIMENTAL && X86_PC)
917 select SPARSEMEM_STATIC if X86_32
918 select SPARSEMEM_VMEMMAP_ENABLE if X86_64
920 config ARCH_SELECT_MEMORY_MODEL
922 depends on ARCH_SPARSEMEM_ENABLE
924 config ARCH_MEMORY_PROBE
926 depends on MEMORY_HOTPLUG
931 bool "Allocate 3rd-level pagetables from highmem"
932 depends on X86_32 && (HIGHMEM4G || HIGHMEM64G)
934 The VM uses one page table entry for each page of physical memory.
935 For systems with a lot of RAM, this can be wasteful of precious
936 low memory. Setting this option will put user-space page table
937 entries in high memory.
939 config MATH_EMULATION
941 prompt "Math emulation" if X86_32
943 Linux can emulate a math coprocessor (used for floating point
944 operations) if you don't have one. 486DX and Pentium processors have
945 a math coprocessor built in, 486SX and 386 do not, unless you added
946 a 487DX or 387, respectively. (The messages during boot time can
947 give you some hints here ["man dmesg"].) Everyone needs either a
948 coprocessor or this emulation.
950 If you don't have a math coprocessor, you need to say Y here; if you
951 say Y here even though you have a coprocessor, the coprocessor will
952 be used nevertheless. (This behavior can be changed with the kernel
953 command line option "no387", which comes handy if your coprocessor
954 is broken. Try "man bootparam" or see the documentation of your boot
955 loader (lilo or loadlin) about how to pass options to the kernel at
956 boot time.) This means that it is a good idea to say Y here if you
957 intend to use this kernel on different machines.
959 More information about the internals of the Linux math coprocessor
960 emulation can be found in <file:arch/x86/math-emu/README>.
962 If you are not sure, say Y; apart from resulting in a 66 KB bigger
963 kernel, it won't hurt.
966 bool "MTRR (Memory Type Range Register) support"
968 On Intel P6 family processors (Pentium Pro, Pentium II and later)
969 the Memory Type Range Registers (MTRRs) may be used to control
970 processor access to memory ranges. This is most useful if you have
971 a video (VGA) card on a PCI or AGP bus. Enabling write-combining
972 allows bus write transfers to be combined into a larger transfer
973 before bursting over the PCI/AGP bus. This can increase performance
974 of image write operations 2.5 times or more. Saying Y here creates a
975 /proc/mtrr file which may be used to manipulate your processor's
976 MTRRs. Typically the X server should use this.
978 This code has a reasonably generic interface so that similar
979 control registers on other processors can be easily supported
982 The Cyrix 6x86, 6x86MX and M II processors have Address Range
983 Registers (ARRs) which provide a similar functionality to MTRRs. For
984 these, the ARRs are used to emulate the MTRRs.
985 The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
986 MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing
987 write-combining. All of these processors are supported by this code
988 and it makes sense to say Y here if you have one of them.
990 Saying Y here also fixes a problem with buggy SMP BIOSes which only
991 set the MTRRs for the boot CPU and not for the secondary CPUs. This
992 can lead to all sorts of problems, so it's good to say Y here.
994 You can safely say Y even if your machine doesn't have MTRRs, you'll
995 just add about 9 KB to your kernel.
997 See <file:Documentation/mtrr.txt> for more information.
1001 prompt "EFI runtime service support"
1004 This enables the kernel to use EFI runtime services that are
1005 available (such as the EFI variable services).
1007 This option is only useful on systems that have EFI firmware.
1008 In addition, you should use the latest ELILO loader available
1009 at <http://elilo.sourceforge.net> in order to take advantage
1010 of EFI runtime services. However, even with this option, the
1011 resultant kernel should continue to boot on existing non-EFI
1016 prompt "Enable kernel irq balancing"
1017 depends on X86_32 && SMP && X86_IO_APIC
1019 The default yes will allow the kernel to do irq load balancing.
1020 Saying no will keep the kernel from doing irq load balancing.
1024 prompt "Enable seccomp to safely compute untrusted bytecode"
1027 This kernel feature is useful for number crunching applications
1028 that may need to compute untrusted bytecode during their
1029 execution. By using pipes or other transports made available to
1030 the process as file descriptors supporting the read/write
1031 syscalls, it's possible to isolate those applications in
1032 their own address space using seccomp. Once seccomp is
1033 enabled via /proc/<pid>/seccomp, it cannot be disabled
1034 and the task is only allowed to execute a few safe syscalls
1035 defined by each seccomp mode.
1037 If unsure, say Y. Only embedded should say N here.
1039 config CC_STACKPROTECTOR
1040 bool "Enable -fstack-protector buffer overflow detection (EXPERIMENTAL)"
1041 depends on X86_64 && EXPERIMENTAL
1043 This option turns on the -fstack-protector GCC feature. This
1044 feature puts, at the beginning of critical functions, a canary
1045 value on the stack just before the return address, and validates
1046 the value just before actually returning. Stack based buffer
1047 overflows (that need to overwrite this return address) now also
1048 overwrite the canary, which gets detected and the attack is then
1049 neutralized via a kernel panic.
1051 This feature requires gcc version 4.2 or above, or a distribution
1052 gcc with the feature backported. Older versions are automatically
1053 detected and for those versions, this configuration option is ignored.
1055 config CC_STACKPROTECTOR_ALL
1056 bool "Use stack-protector for all functions"
1057 depends on CC_STACKPROTECTOR
1059 Normally, GCC only inserts the canary value protection for
1060 functions that use large-ish on-stack buffers. By enabling
1061 this option, GCC will be asked to do this for ALL functions.
1063 source kernel/Kconfig.hz
1066 bool "kexec system call"
1068 kexec is a system call that implements the ability to shutdown your
1069 current kernel, and to start another kernel. It is like a reboot
1070 but it is independent of the system firmware. And like a reboot
1071 you can start any kernel with it, not just Linux.
1073 The name comes from the similarity to the exec system call.
1075 It is an ongoing process to be certain the hardware in a machine
1076 is properly shutdown, so do not be surprised if this code does not
1077 initially work for you. It may help to enable device hotplugging
1078 support. As of this writing the exact hardware interface is
1079 strongly in flux, so no good recommendation can be made.
1082 bool "kernel crash dumps (EXPERIMENTAL)"
1083 depends on EXPERIMENTAL
1084 depends on X86_64 || (X86_32 && HIGHMEM)
1086 Generate crash dump after being started by kexec.
1087 This should be normally only set in special crash dump kernels
1088 which are loaded in the main kernel with kexec-tools into
1089 a specially reserved region and then later executed after
1090 a crash by kdump/kexec. The crash dump kernel must be compiled
1091 to a memory address not used by the main kernel or BIOS using
1092 PHYSICAL_START, or it must be built as a relocatable image
1093 (CONFIG_RELOCATABLE=y).
1094 For more details see Documentation/kdump/kdump.txt
1096 config PHYSICAL_START
1097 hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
1098 default "0x1000000" if X86_NUMAQ
1099 default "0x200000" if X86_64
1102 This gives the physical address where the kernel is loaded.
1104 If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
1105 bzImage will decompress itself to above physical address and
1106 run from there. Otherwise, bzImage will run from the address where
1107 it has been loaded by the boot loader and will ignore above physical
1110 In normal kdump cases one does not have to set/change this option
1111 as now bzImage can be compiled as a completely relocatable image
1112 (CONFIG_RELOCATABLE=y) and be used to load and run from a different
1113 address. This option is mainly useful for the folks who don't want
1114 to use a bzImage for capturing the crash dump and want to use a
1115 vmlinux instead. vmlinux is not relocatable hence a kernel needs
1116 to be specifically compiled to run from a specific memory area
1117 (normally a reserved region) and this option comes handy.
1119 So if you are using bzImage for capturing the crash dump, leave
1120 the value here unchanged to 0x100000 and set CONFIG_RELOCATABLE=y.
1121 Otherwise if you plan to use vmlinux for capturing the crash dump
1122 change this value to start of the reserved region (Typically 16MB
1123 0x1000000). In other words, it can be set based on the "X" value as
1124 specified in the "crashkernel=YM@XM" command line boot parameter
1125 passed to the panic-ed kernel. Typically this parameter is set as
1126 crashkernel=64M@16M. Please take a look at
1127 Documentation/kdump/kdump.txt for more details about crash dumps.
1129 Usage of bzImage for capturing the crash dump is recommended as
1130 one does not have to build two kernels. Same kernel can be used
1131 as production kernel and capture kernel. Above option should have
1132 gone away after relocatable bzImage support is introduced. But it
1133 is present because there are users out there who continue to use
1134 vmlinux for dump capture. This option should go away down the
1137 Don't change this unless you know what you are doing.
1140 bool "Build a relocatable kernel (EXPERIMENTAL)"
1141 depends on EXPERIMENTAL
1143 This builds a kernel image that retains relocation information
1144 so it can be loaded someplace besides the default 1MB.
1145 The relocations tend to make the kernel binary about 10% larger,
1146 but are discarded at runtime.
1148 One use is for the kexec on panic case where the recovery kernel
1149 must live at a different physical address than the primary
1152 Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address
1153 it has been loaded at and the compile time physical address
1154 (CONFIG_PHYSICAL_START) is ignored.
1156 config PHYSICAL_ALIGN
1158 prompt "Alignment value to which kernel should be aligned" if X86_32
1159 default "0x100000" if X86_32
1160 default "0x200000" if X86_64
1161 range 0x2000 0x400000
1163 This value puts the alignment restrictions on physical address
1164 where kernel is loaded and run from. Kernel is compiled for an
1165 address which meets above alignment restriction.
1167 If bootloader loads the kernel at a non-aligned address and
1168 CONFIG_RELOCATABLE is set, kernel will move itself to nearest
1169 address aligned to above value and run from there.
1171 If bootloader loads the kernel at a non-aligned address and
1172 CONFIG_RELOCATABLE is not set, kernel will ignore the run time
1173 load address and decompress itself to the address it has been
1174 compiled for and run from there. The address for which kernel is
1175 compiled already meets above alignment restrictions. Hence the
1176 end result is that kernel runs from a physical address meeting
1177 above alignment restrictions.
1179 Don't change this unless you know what you are doing.
1182 bool "Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL)"
1183 depends on SMP && HOTPLUG && EXPERIMENTAL && !X86_VOYAGER
1185 Say Y here to experiment with turning CPUs off and on, and to
1186 enable suspend on SMP systems. CPUs can be controlled through
1187 /sys/devices/system/cpu.
1188 Say N if you want to disable CPU hotplug and don't need to
1193 prompt "Compat VDSO support"
1194 depends on X86_32 || IA32_EMULATION
1196 Map the 32-bit VDSO to the predictable old-style address too.
1198 Say N here if you are running a sufficiently recent glibc
1199 version (2.3.3 or later), to remove the high-mapped
1200 VDSO mapping and to exclusively use the randomized VDSO.
1206 config ARCH_ENABLE_MEMORY_HOTPLUG
1208 depends on X86_64 || (X86_32 && HIGHMEM)
1210 config HAVE_ARCH_EARLY_PFN_TO_NID
1214 menu "Power management options"
1215 depends on !X86_VOYAGER
1217 config ARCH_HIBERNATION_HEADER
1219 depends on X86_64 && HIBERNATION
1221 source "kernel/power/Kconfig"
1223 source "drivers/acpi/Kconfig"
1228 depends on APM || APM_MODULE
1231 tristate "APM (Advanced Power Management) BIOS support"
1232 depends on X86_32 && PM_SLEEP && !X86_VISWS
1234 APM is a BIOS specification for saving power using several different
1235 techniques. This is mostly useful for battery powered laptops with
1236 APM compliant BIOSes. If you say Y here, the system time will be
1237 reset after a RESUME operation, the /proc/apm device will provide
1238 battery status information, and user-space programs will receive
1239 notification of APM "events" (e.g. battery status change).
1241 If you select "Y" here, you can disable actual use of the APM
1242 BIOS by passing the "apm=off" option to the kernel at boot time.
1244 Note that the APM support is almost completely disabled for
1245 machines with more than one CPU.
1247 In order to use APM, you will need supporting software. For location
1248 and more information, read <file:Documentation/pm.txt> and the
1249 Battery Powered Linux mini-HOWTO, available from
1250 <http://www.tldp.org/docs.html#howto>.
1252 This driver does not spin down disk drives (see the hdparm(8)
1253 manpage ("man 8 hdparm") for that), and it doesn't turn off
1254 VESA-compliant "green" monitors.
1256 This driver does not support the TI 4000M TravelMate and the ACER
1257 486/DX4/75 because they don't have compliant BIOSes. Many "green"
1258 desktop machines also don't have compliant BIOSes, and this driver
1259 may cause those machines to panic during the boot phase.
1261 Generally, if you don't have a battery in your machine, there isn't
1262 much point in using this driver and you should say N. If you get
1263 random kernel OOPSes or reboots that don't seem to be related to
1264 anything, try disabling/enabling this option (or disabling/enabling
1267 Some other things you should try when experiencing seemingly random,
1270 1) make sure that you have enough swap space and that it is
1272 2) pass the "no-hlt" option to the kernel
1273 3) switch on floating point emulation in the kernel and pass
1274 the "no387" option to the kernel
1275 4) pass the "floppy=nodma" option to the kernel
1276 5) pass the "mem=4M" option to the kernel (thereby disabling
1277 all but the first 4 MB of RAM)
1278 6) make sure that the CPU is not over clocked.
1279 7) read the sig11 FAQ at <http://www.bitwizard.nl/sig11/>
1280 8) disable the cache from your BIOS settings
1281 9) install a fan for the video card or exchange video RAM
1282 10) install a better fan for the CPU
1283 11) exchange RAM chips
1284 12) exchange the motherboard.
1286 To compile this driver as a module, choose M here: the
1287 module will be called apm.
1291 config APM_IGNORE_USER_SUSPEND
1292 bool "Ignore USER SUSPEND"
1294 This option will ignore USER SUSPEND requests. On machines with a
1295 compliant APM BIOS, you want to say N. However, on the NEC Versa M
1296 series notebooks, it is necessary to say Y because of a BIOS bug.
1298 config APM_DO_ENABLE
1299 bool "Enable PM at boot time"
1301 Enable APM features at boot time. From page 36 of the APM BIOS
1302 specification: "When disabled, the APM BIOS does not automatically
1303 power manage devices, enter the Standby State, enter the Suspend
1304 State, or take power saving steps in response to CPU Idle calls."
1305 This driver will make CPU Idle calls when Linux is idle (unless this
1306 feature is turned off -- see "Do CPU IDLE calls", below). This
1307 should always save battery power, but more complicated APM features
1308 will be dependent on your BIOS implementation. You may need to turn
1309 this option off if your computer hangs at boot time when using APM
1310 support, or if it beeps continuously instead of suspending. Turn
1311 this off if you have a NEC UltraLite Versa 33/C or a Toshiba
1312 T400CDT. This is off by default since most machines do fine without
1316 bool "Make CPU Idle calls when idle"
1318 Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop.
1319 On some machines, this can activate improved power savings, such as
1320 a slowed CPU clock rate, when the machine is idle. These idle calls
1321 are made after the idle loop has run for some length of time (e.g.,
1322 333 mS). On some machines, this will cause a hang at boot time or
1323 whenever the CPU becomes idle. (On machines with more than one CPU,
1324 this option does nothing.)
1326 config APM_DISPLAY_BLANK
1327 bool "Enable console blanking using APM"
1329 Enable console blanking using the APM. Some laptops can use this to
1330 turn off the LCD backlight when the screen blanker of the Linux
1331 virtual console blanks the screen. Note that this is only used by
1332 the virtual console screen blanker, and won't turn off the backlight
1333 when using the X Window system. This also doesn't have anything to
1334 do with your VESA-compliant power-saving monitor. Further, this
1335 option doesn't work for all laptops -- it might not turn off your
1336 backlight at all, or it might print a lot of errors to the console,
1337 especially if you are using gpm.
1339 config APM_ALLOW_INTS
1340 bool "Allow interrupts during APM BIOS calls"
1342 Normally we disable external interrupts while we are making calls to
1343 the APM BIOS as a measure to lessen the effects of a badly behaving
1344 BIOS implementation. The BIOS should reenable interrupts if it
1345 needs to. Unfortunately, some BIOSes do not -- especially those in
1346 many of the newer IBM Thinkpads. If you experience hangs when you
1347 suspend, try setting this to Y. Otherwise, say N.
1349 config APM_REAL_MODE_POWER_OFF
1350 bool "Use real mode APM BIOS call to power off"
1352 Use real mode APM BIOS calls to switch off the computer. This is
1353 a work-around for a number of buggy BIOSes. Switch this option on if
1354 your computer crashes instead of powering off properly.
1358 source "arch/x86/kernel/cpu/cpufreq/Kconfig"
1360 source "drivers/cpuidle/Kconfig"
1365 menu "Bus options (PCI etc.)"
1368 bool "PCI support" if !X86_VISWS
1369 depends on !X86_VOYAGER
1371 select ARCH_SUPPORTS_MSI if (X86_LOCAL_APIC && X86_IO_APIC)
1373 Find out whether you have a PCI motherboard. PCI is the name of a
1374 bus system, i.e. the way the CPU talks to the other stuff inside
1375 your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or
1376 VESA. If you have PCI, say Y, otherwise N.
1379 prompt "PCI access mode"
1380 depends on X86_32 && PCI && !X86_VISWS
1383 On PCI systems, the BIOS can be used to detect the PCI devices and
1384 determine their configuration. However, some old PCI motherboards
1385 have BIOS bugs and may crash if this is done. Also, some embedded
1386 PCI-based systems don't have any BIOS at all. Linux can also try to
1387 detect the PCI hardware directly without using the BIOS.
1389 With this option, you can specify how Linux should detect the
1390 PCI devices. If you choose "BIOS", the BIOS will be used,
1391 if you choose "Direct", the BIOS won't be used, and if you
1392 choose "MMConfig", then PCI Express MMCONFIG will be used.
1393 If you choose "Any", the kernel will try MMCONFIG, then the
1394 direct access method and falls back to the BIOS if that doesn't
1395 work. If unsure, go with the default, which is "Any".
1400 config PCI_GOMMCONFIG
1413 depends on X86_32 && !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
1415 # x86-64 doesn't support PCI BIOS access from long mode so always go direct.
1418 depends on PCI && (X86_64 || (PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
1422 depends on X86_32 && PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
1429 bool "Support mmconfig PCI config space access"
1430 depends on X86_64 && PCI && ACPI
1433 bool "Support for DMA Remapping Devices (EXPERIMENTAL)"
1434 depends on X86_64 && PCI_MSI && ACPI && EXPERIMENTAL
1436 DMA remapping (DMAR) devices support enables independent address
1437 translations for Direct Memory Access (DMA) from devices.
1438 These DMA remapping devices are reported via ACPI tables
1439 and include PCI device scope covered by these DMA
1444 prompt "Support for Graphics workaround"
1447 Current Graphics drivers tend to use physical address
1448 for DMA and avoid using DMA APIs. Setting this config
1449 option permits the IOMMU driver to set a unity map for
1450 all the OS-visible memory. Hence the driver can continue
1451 to use physical addresses for DMA.
1453 config DMAR_FLOPPY_WA
1457 Floppy disk drivers are know to bypass DMA API calls
1458 thereby failing to work when IOMMU is enabled. This
1459 workaround will setup a 1:1 mapping for the first
1460 16M to make floppy (an ISA device) work.
1462 source "drivers/pci/pcie/Kconfig"
1464 source "drivers/pci/Kconfig"
1466 # x86_64 have no ISA slots, but do have ISA-style DMA.
1474 depends on !(X86_VOYAGER || X86_VISWS)
1476 Find out whether you have ISA slots on your motherboard. ISA is the
1477 name of a bus system, i.e. the way the CPU talks to the other stuff
1478 inside your box. Other bus systems are PCI, EISA, MicroChannel
1479 (MCA) or VESA. ISA is an older system, now being displaced by PCI;
1480 newer boards don't support it. If you have ISA, say Y, otherwise N.
1486 The Extended Industry Standard Architecture (EISA) bus was
1487 developed as an open alternative to the IBM MicroChannel bus.
1489 The EISA bus provided some of the features of the IBM MicroChannel
1490 bus while maintaining backward compatibility with cards made for
1491 the older ISA bus. The EISA bus saw limited use between 1988 and
1492 1995 when it was made obsolete by the PCI bus.
1494 Say Y here if you are building a kernel for an EISA-based machine.
1498 source "drivers/eisa/Kconfig"
1501 bool "MCA support" if !(X86_VISWS || X86_VOYAGER)
1502 default y if X86_VOYAGER
1504 MicroChannel Architecture is found in some IBM PS/2 machines and
1505 laptops. It is a bus system similar to PCI or ISA. See
1506 <file:Documentation/mca.txt> (and especially the web page given
1507 there) before attempting to build an MCA bus kernel.
1509 source "drivers/mca/Kconfig"
1512 tristate "NatSemi SCx200 support"
1513 depends on !X86_VOYAGER
1515 This provides basic support for National Semiconductor's
1516 (now AMD's) Geode processors. The driver probes for the
1517 PCI-IDs of several on-chip devices, so its a good dependency
1518 for other scx200_* drivers.
1520 If compiled as a module, the driver is named scx200.
1522 config SCx200HR_TIMER
1523 tristate "NatSemi SCx200 27MHz High-Resolution Timer Support"
1524 depends on SCx200 && GENERIC_TIME
1527 This driver provides a clocksource built upon the on-chip
1528 27MHz high-resolution timer. Its also a workaround for
1529 NSC Geode SC-1100's buggy TSC, which loses time when the
1530 processor goes idle (as is done by the scheduler). The
1531 other workaround is idle=poll boot option.
1533 config GEODE_MFGPT_TIMER
1535 prompt "Geode Multi-Function General Purpose Timer (MFGPT) events"
1536 depends on MGEODE_LX && GENERIC_TIME && GENERIC_CLOCKEVENTS
1538 This driver provides a clock event source based on the MFGPT
1539 timer(s) in the CS5535 and CS5536 companion chip for the geode.
1540 MFGPTs have a better resolution and max interval than the
1541 generic PIT, and are suitable for use as high-res timers.
1547 depends on AGP_AMD64 || (X86_64 && (GART_IOMMU || (PCI && NUMA)))
1549 source "drivers/pcmcia/Kconfig"
1551 source "drivers/pci/hotplug/Kconfig"
1556 menu "Executable file formats / Emulations"
1558 source "fs/Kconfig.binfmt"
1560 config IA32_EMULATION
1561 bool "IA32 Emulation"
1563 select COMPAT_BINFMT_ELF
1565 Include code to run 32-bit programs under a 64-bit kernel. You should
1566 likely turn this on, unless you're 100% sure that you don't have any
1567 32-bit programs left.
1570 tristate "IA32 a.out support"
1571 depends on IA32_EMULATION
1573 Support old a.out binaries in the 32bit emulation.
1577 depends on IA32_EMULATION
1579 config COMPAT_FOR_U64_ALIGNMENT
1583 config SYSVIPC_COMPAT
1585 depends on X86_64 && COMPAT && SYSVIPC
1590 source "net/Kconfig"
1592 source "drivers/Kconfig"
1594 source "drivers/firmware/Kconfig"
1598 source "arch/x86/Kconfig.debug"
1600 source "security/Kconfig"
1602 source "crypto/Kconfig"
1604 source "arch/x86/kvm/Kconfig"
1606 source "lib/Kconfig"