User:ZyMOS/Howto configure the linux kernel/arch/i386

User:ZyMOS/Howto configure the linux kernel / arch / i386


 * For a description of the syntax of this configuration file,
 * see Documentation/kbuild/kconfig-language.txt.
 * see Documentation/kbuild/kconfig-language.txt.

"Linux Kernel Configuration"


 * Option: X86_32
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y
 * This is Linux's home port. Linux was originally native to the Intel 386, and runs on all the later x86 processors including the Intel 486, 586, Pentiums, and various instruction-set-compatible chips by AMD, Cyrix, and others.


 * Option: SEMAPHORE_SLEEPERS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: X86
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: MMU
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: SBUS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)


 * Option: UID16
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: GENERIC_ISA_DMA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: GENERIC_IOMAP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: ARCH_MAY_HAVE_PC_FDC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: User:ZyMOS/Howto configure the linux kernel/init

Processor type and features
"Subarchitecture Type"
 * default X86_PC


 * Option: X86_PC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "PC-compatible"
 * Choose this option if your computer is a standard PC or compatible.


 * Option: X86_ELAN
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "AMD Elan"
 * Select this for an AMD Elan processor.
 * Do not use this option for K6/Athlon/Opteron processors!
 * If unsure, choose "PC-compatible" instead.


 * Option: X86_VOYAGER
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Voyager (NCR)"
 * Voyager is an MCA-based 32-way capable SMP architecture proprietary to NCR Corp. Machine classes 345x/35xx/4100/51xx are Voyager-based.
 * *** WARNING ***
 * If you do not specifically know you have a Voyager based machine, say N here, otherwise the kernel you build will not be bootable.


 * Option: X86_NUMAQ
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "NUMAQ (IBM/Sequent)"
 * select NUMA
 * This option is used for getting Linux to run on a (IBM/Sequent) NUMA multiquad box. This changes the way that processors are bootstrapped, and uses Clustered Logical APIC addressing mode instead of Flat Logical. You will need a new lynxer.elf file to flash your firmware with - send email to .


 * Option: X86_SUMMIT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Summit/EXA (IBM x440)"
 * depends on SMP
 * This option is needed for IBM systems that use the Summit/EXA chipset. In particular, it is needed for the x440.
 * If you don't have one of these computers, you should say N here.


 * Option: X86_BIGSMP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Support for other sub-arch SMP systems with more than 8 CPUs"
 * depends on SMP
 * This option is needed for the systems that have more than 8 CPUs and if the system is not of any sub-arch type above.
 * If you don't have such a system, you should say N here.


 * Option: X86_VISWS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "SGI 320/540 (Visual Workstation)"
 * The SGI Visual Workstation series is an IA32-based workstation based on SGI systems chips with some legacy PC hardware attached.
 * Say Y here to create a kernel to run on the SGI 320 or 540.
 * A kernel compiled for the Visual Workstation will not run on PCs and vice versa. See  for details.


 * Option: X86_GENERICARCH
 * Kernel Versions: 2.6.15.6 ...     bool "Generic architecture (Summit, bigsmp, ES7000, default)"      depends on SMP      help         This option compiles in the Summit, bigsmp, ES7000, default subarchitectures. It is intended for a generic binary kernel.


 * Option: X86_ES7000
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Support for Unisys ES7000 IA32 series"
 * depends on SMP
 * Support for Unisys ES7000 systems. Say 'Y' here if this kernel is supposed to run on an IA32-based Unisys ES7000 system. Only choose this option if you have such a system, otherwise you should say N here.


 * Option: ACPI_SRAT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y
 * depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)


 * Option: X86_SUMMIT_NUMA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y
 * depends on NUMA && (X86_SUMMIT || X86_GENERICARCH)


 * Option: X86_CYCLONE_TIMER
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y
 * depends on X86_SUMMIT || X86_GENERICARCH


 * Option: ES7000_CLUSTERED_APIC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y
 * depends on SMP && X86_ES7000 && MPENTIUMIII


 * Option: User:ZyMOS/Howto configure the linux kernel/arch/i386.cpu"


 * Option: HPET_TIMER
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "HPET Timer Support"
 * This enables the use of the HPET for the kernel's internal timer. HPET is the next generation timer replacing legacy 8254s. You can safely choose Y here. However, HPET will only be activated if the platform and the BIOS support this feature. Otherwise the 8254 will be used for timing services.
 * Choose N to continue using the legacy 8254 timer.


 * Option: HPET_EMULATE_RTC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on HPET_TIMER && RTC=y
 * default y


 * Option: SMP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Symmetric multi-processing support"
 * This enables support for systems with more than one CPU. If you have a system with only one CPU, like most personal computers, say N. If you have a system with more than one CPU, say Y.
 * If you say N here, the kernel will run on single and multiprocessor machines, but will use only one CPU of a multiprocessor machine. If you say Y here, the kernel will run on many, but not all, singleprocessor machines. On a singleprocessor machine, the kernel will run faster if you say N here.
 * Note that if you say Y here and choose architecture "586" or "Pentium" under "Processor family", the kernel will not work on 486 architectures. Similarly, multiprocessor kernels for the "PPro" architecture may not work on all Pentium based boards.
 * People using multiprocessor machines who say Y here should also say Y to "Enhanced Real Time Clock Support", below. The "Advanced Power Management" code will be disabled if you say Y here.
 * See also the , ,  and the SMP-HOWTO available at .
 * If you don't know what to do here, say N.

"Maximum number of CPUs (2-255)" 2 255
 * Option: NR_CPUS
 * Kernel Versions: 2.6.15.6 ...
 * depends on SMP
 * default "32" if X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000
 * default "8"
 * This allows you to specify the maximum number of CPUs which this kernel will support. The maximum supported value is 255 and the minimum value which makes sense is 2.
 * This is purely to save memory - each supported CPU adds approximately eight kilobytes to the kernel image.


 * Option: SCHED_SMT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "SMT (Hyperthreading) scheduler support"
 * depends on SMP
 * default off
 * SMT scheduler support improves the CPU scheduler's decision making when dealing with Intel Pentium 4 chips with HyperThreading at a cost of slightly increased overhead in some places. If unsure say N here.


 * Option: User:ZyMOS/Howto configure the linux kernel/kernel.preempt"


 * Option: X86_UP_APIC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Local APIC support on uniprocessors"
 * depends on !SMP && !(X86_VISWS || X86_VOYAGER)
 * A local APIC (Advanced Programmable Interrupt Controller) is an integrated interrupt controller in the CPU. If you have a single-CPU system which has a processor with a local APIC, you can say Y here to enable and use it. If you say Y here even though your machine doesn't have a local APIC, then the kernel will still run with no slowdown at all. The local APIC supports CPU-generated self-interrupts (timer, performance counters), and the NMI watchdog which detects hard lockups.


 * Option: X86_UP_IOAPIC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "IO-APIC support on uniprocessors"
 * depends on X86_UP_APIC
 * An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an SMP-capable replacement for PC-style interrupt controllers. Most SMP systems and many recent uniprocessor systems have one.
 * If you have a single-CPU system with an IO-APIC, you can say Y here to use it. If you say Y here even though your machine doesn't have an IO-APIC, then the kernel will still run with no slowdown at all.


 * Option: X86_LOCAL_APIC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on X86_UP_APIC || ((X86_VISWS || SMP) && !X86_VOYAGER)
 * default y


 * Option: X86_IO_APIC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on X86_UP_IOAPIC || (SMP && !(X86_VISWS || X86_VOYAGER))
 * default y


 * Option: X86_VISWS_APIC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on X86_VISWS
 * default y


 * Option: X86_MCE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Machine Check Exception"
 * depends on !X86_VOYAGER
 * Machine Check Exception support allows the processor to notify the kernel if it detects a problem (e.g. overheating, component failure). The action the kernel takes depends on the severity of the problem, ranging from a warning message on the console, to halting the machine. Your processor must be a Pentium or newer to support this - check the flags in /proc/cpuinfo for mce. Note that some older Pentium systems have a design flaw which leads to false MCE events - hence MCE is disabled on all P5 processors, unless explicitly enabled with "mce" as a boot argument.  Similarly, if MCE is built in and creates a problem on some new non-standard machine, you can boot with "nomce" to disable it.  MCE support simply ignores non-MCE processors like the 386 and 486, so nearly everyone can say Y here.


 * Option: X86_MCE_NONFATAL
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "Check for non-fatal errors on AMD Athlon/Duron / Intel Pentium 4"
 * depends on X86_MCE
 * Enabling this feature starts a timer that triggers every 5 seconds which will look at the machine check registers to see if anything happened. Non-fatal problems automatically get corrected (but still logged). Disable this if you don't want to see these messages. Seeing the messages this option prints out may be indicative of dying hardware, or out-of-spec (ie, overclocked) hardware. This option only does something on certain CPUs. (AMD Athlon/Duron and Intel Pentium 4)


 * Option: X86_MCE_P4THERMAL
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "check for P4 thermal throttling interrupt."
 * depends on X86_MCE && (X86_UP_APIC || SMP) && !X86_VISWS
 * Enabling this feature will cause a message to be printed when the P4 enters thermal throttling.


 * Option: TOSHIBA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "Toshiba Laptop support"
 * This adds a driver to safely access the System Management Mode of the CPU on Toshiba portables with a genuine Toshiba BIOS. It does not work on models with a Phoenix BIOS. The System Management Mode is used to set the BIOS and power saving options on Toshiba portables.
 * For information on utilities to make use of this driver see the Toshiba Linux utilities web site at: .
 * Say Y if you intend to run this kernel on a Toshiba portable. Say N otherwise.


 * Option: I8K
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "Dell laptop support"
 * This adds a driver to safely access the System Management Mode of the CPU on the Dell Inspiron 8000. The System Management Mode is used to read cpu temperature and cooling fan status and to control the fans on the I8K portables.
 * This driver has been tested only on the Inspiron 8000 but it may also work with other Dell laptops. You can force loading on other models by passing the parameter `force=1' to the module. Use at your own risk.
 * For information on utilities to make use of this driver see the I8K Linux utilities web site at: 
 * Say Y if you intend to run this kernel on a Dell Inspiron 8000. Say N otherwise.


 * Option: X86_REBOOTFIXUPS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Enable X86 board specific fixups for reboot"
 * depends on X86
 * default n
 * This enables chipset and/or board specific fixups to be done in order to get reboot to work correctly. This is only needed on some combinations of hardware and BIOS. The symptom, for which this config is intended, is when reboot ends with a stalled/hung system.
 * Currently, the only fixup is for the Geode GX1/CS5530A/TROM2.1. combination.
 * Say Y if you want to enable the fixup. Currently, it's safe to enable this option even if you don't need it. Say N otherwise.


 * Option: MICROCODE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "/dev/cpu/microcode - Intel IA32 CPU microcode support"
 * If you say Y here and also to "/dev file system support" in the 'File systems' section, you will be able to update the microcode on Intel processors in the IA32 family, e.g. Pentium Pro, Pentium II, Pentium III, Pentium 4, Xeon etc. You will obviously need the actual microcode binary data itself which is not shipped with the Linux kernel.
 * For latest news and information on obtaining all the required ingredients for this driver, check: .
 * To compile this driver as a module, choose M here: the module will be called microcode.


 * Option: X86_MSR
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "/dev/cpu/*/msr - Model-specific register support"
 * This device gives privileged processes access to the x86 Model-Specific Registers (MSRs). It is a character device with major 202 and minors 0 to 31 for /dev/cpu/0/msr to /dev/cpu/31/msr. MSR accesses are directed to a specific CPU on multi-processor systems.


 * Option: X86_CPUID
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "/dev/cpu/*/cpuid - CPU information support"
 * This device gives processes access to the x86 CPUID instruction to be executed on a specific processor. It is a character device with major 203 and minors 0 to 31 for /dev/cpu/0/cpuid to /dev/cpu/31/cpuid.


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/firmware

"High Memory Support"
 * default NOHIGHMEM


 * Option: NOHIGHMEM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "off"
 * Linux can use up to 64 Gigabytes of physical memory on x86 systems. However, the address space of 32-bit x86 processors is only 4 Gigabytes large. That means that, if you have a large amount of physical memory, not all of it can be "permanently mapped" by the kernel. The physical memory that's not permanently mapped is called "high memory".
 * If you are compiling a kernel which will never run on a machine with more than 1 Gigabyte total physical RAM, answer "off" here (default choice and suitable for most users). This will result in a "3GB/1GB" split: 3GB are mapped so that each process sees a 3GB virtual memory space and the remaining part of the 4GB virtual memory space is used by the kernel to permanently map as much physical memory as possible.
 * If the machine has between 1 and 4 Gigabytes physical RAM, then answer "4GB" here.
 * If more than 4 Gigabytes is used then answer "64GB" here. This selection turns Intel PAE (Physical Address Extension) mode on. PAE implements 3-level paging on IA32 processors. PAE is fully supported by Linux, PAE mode is implemented on all recent Intel processors (Pentium Pro and better). NOTE: If you say "64GB" here, then the kernel will not boot on CPUs that don't support PAE!
 * The actual amount of total physical memory will either be auto detected or can be forced by using a kernel command line option such as "mem=256M". (Try "man bootparam" or see the documentation of your boot loader (lilo or loadlin) about how to pass options to the kernel at boot time.)
 * If unsure, say "off".


 * Option: HIGHMEM4G
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "4GB"
 * Select this if you have a 32-bit processor and between 1 and 4 gigabytes of physical RAM.


 * Option: HIGHMEM64G
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "64GB"
 * Select this if you have a 32-bit processor and more than 4 gigabytes of physical RAM.


 * Option: HIGHMEM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on HIGHMEM64G || HIGHMEM4G
 * default y


 * Option: X86_PAE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on HIGHMEM64G
 * default y


 * Common NUMA Features


 * Option: NUMA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Numa Memory Allocation and Scheduler Support"
 * depends on SMP && HIGHMEM64G && (X86_NUMAQ || X86_GENERICARCH || (X86_SUMMIT && ACPI))
 * default n if X86_PC
 * default y if (X86_NUMAQ || X86_SUMMIT)
 * select SPARSEMEM_STATIC


 * Need comments to help the hapless user trying to turn on NUMA support

"NUMA (NUMA-Q) requires SMP, 64GB highmem support"
 * depends on X86_NUMAQ && (!HIGHMEM64G || !SMP)

"NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
 * depends on X86_SUMMIT && (!HIGHMEM64G || !ACPI)


 * Option: HAVE_ARCH_BOOTMEM_NODE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on NUMA
 * default y


 * Option: ARCH_HAVE_MEMORY_PRESENT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on DISCONTIGMEM
 * default y


 * Option: NEED_NODE_MEMMAP_SIZE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on DISCONTIGMEM || SPARSEMEM
 * default y


 * Option: HAVE_ARCH_ALLOC_REMAP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on NUMA
 * default y

_bool y
 * Option: ARCH_DISCONTIGMEM_ENABLE
 * Kernel Versions: 2.6.15.6 ...
 * depends on NUMA

_bool y
 * Option: ARCH_DISCONTIGMEM_DEFAULT
 * Kernel Versions: 2.6.15.6 ...
 * depends on NUMA

_bool y
 * Option: ARCH_SPARSEMEM_ENABLE
 * Kernel Versions: 2.6.15.6 ...
 * depends on NUMA

_bool y
 * Option: ARCH_SELECT_MEMORY_MODEL
 * Kernel Versions: 2.6.15.6 ...
 * depends on ARCH_SPARSEMEM_ENABLE


 * Option: User:ZyMOS/Howto configure the linux kernel/mm


 * Option: HAVE_ARCH_EARLY_PFN_TO_NID
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y
 * depends on NUMA


 * Option: HIGHPTE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Allocate 3rd-level pagetables from highmem"
 * depends on HIGHMEM4G || HIGHMEM64G
 * The VM uses one page table entry for each page of physical memory. For systems with a lot of RAM, this can be wasteful of precious low memory. Setting this option will put user-space page table entries in high memory.


 * Option: MATH_EMULATION
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Math emulation"
 * Linux can emulate a math coprocessor (used for floating point operations) if you don't have one. 486DX and Pentium processors have a math coprocessor built in, 486SX and 386 do not, unless you added a 487DX or 387, respectively. (The messages during boot time can give you some hints here ["man dmesg"].) Everyone needs either a coprocessor or this emulation.
 * If you don't have a math coprocessor, you need to say Y here; if you say Y here even though you have a coprocessor, the coprocessor will be used nevertheless. (This behavior can be changed with the kernel command line option "no387", which comes handy if your coprocessor is broken. Try "man bootparam" or see the documentation of your boot loader (lilo or loadlin) about how to pass options to the kernel at boot time.) This means that it is a good idea to say Y here if you intend to use this kernel on different machines.
 * More information about the internals of the Linux math coprocessor emulation can be found in .
 * If you are not sure, say Y; apart from resulting in a 66 KB bigger kernel, it won't hurt.


 * Option: MTRR
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "MTRR (Memory Type Range Register) support"
 * On Intel P6 family processors (Pentium Pro, Pentium II and later) the Memory Type Range Registers (MTRRs) may be used to control processor access to memory ranges. This is most useful if you have a video (VGA) card on a PCI or AGP bus. Enabling write-combining allows bus write transfers to be combined into a larger transfer before bursting over the PCI/AGP bus. This can increase performance of image write operations 2.5 times or more. Saying Y here creates a /proc/mtrr file which may be used to manipulate your processor's MTRRs. Typically the X server should use this.
 * This code has a reasonably generic interface so that similar control registers on other processors can be easily supported as well:
 * The Cyrix 6x86, 6x86MX and M II processors have Address Range Registers (ARRs) which provide a similar functionality to MTRRs. For these, the ARRs are used to emulate the MTRRs. The AMD K6-2 (stepping 8 and above) and K6-3 processors have two MTRRs. The Centaur C6 (WinChip) has 8 MCRs, allowing write-combining. All of these processors are supported by this code and it makes sense to say Y here if you have one of them.
 * Saying Y here also fixes a problem with buggy SMP BIOSes which only set the MTRRs for the boot CPU and not for the secondary CPUs. This can lead to all sorts of problems, so it's good to say Y here.
 * You can safely say Y even if your machine doesn't have MTRRs, you'll just add about 9 KB to your kernel.
 * See  for more information.

enables the the kernel to boot on EFI platforms using configuration information passed to it from the firmware. also enables the kernel to use any EFI runtime services that are (such as the EFI variable services).
 * Option: EFI
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Boot from EFI support (EXPERIMENTAL)"
 * depends on ACPI
 * default n

option is only useful on systems that have EFI firmware will result in a kernel image that is ~8k larger. In addition, must use the latest ELILO loader available at  in order to take advantage of initialization using EFI information (neither GRUB nor LILO know about EFI). However, even with this option, the resultant should continue to boot on existing non-EFI platforms.


 * Option: IRQBALANCE
 * Kernel Versions: 2.6.15.6 ...bool "Enable kernel irq balancing"
 * depends on SMP && X86_IO_APIC
 * default y
 * The default yes will allow the kernel to do irq load balancing. Saying no will keep the kernel from doing irq load balancing.


 * turning this on wastes a bunch of space.
 * Summit needs it only when NUMA is on


 * Option: BOOT_IOREMAP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on (((X86_SUMMIT || X86_GENERICARCH) && NUMA) || (X86 && EFI))
 * default y

the kernel with -mregparm=3. This uses a different ABI passes the first three arguments of a function call in registers. will probably break binary only modules.
 * Option: REGPARM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Use register arguments (EXPERIMENTAL)"
 * depends on EXPERIMENTAL
 * default n

feature is only enabled for gcc-3.0 and later - earlier compilers incorrect output with certain kernel constructs when -mregparm=3 is used.


 * Option: SECCOMP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Enable seccomp to safely compute untrusted bytecode"
 * depends on PROC_FS
 * default y
 * This kernel feature is useful for number crunching applications that may need to compute untrusted bytecode during their execution. By using pipes or other transports made available to the process as file descriptors supporting the read/write syscalls, it's possible to isolate those applications in their own address space using seccomp. Once seccomp is enabled via /proc/ /seccomp, it cannot be disabled and the task is only allowed to execute a few safe syscalls defined by each seccomp mode.
 * If unsure, say Y. Only embedded should say N here.


 * Option: User:ZyMOS/Howto configure the linux kernel/kernel.hz

"Physical address where the kernel is loaded" if EMBEDDED
 * Option: PHYSICAL_START
 * Kernel Versions: 2.6.15.6 ...
 * default "0x100000"
 * This gives the physical address where the kernel is loaded. Primarily used in the case of kexec on panic where the fail safe kernel needs to run at a different address than the panic-ed kernel.
 * Don't change this unless you know what you are doing.


 * Option: KEXEC
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "kexec system call (EXPERIMENTAL)"
 * depends on EXPERIMENTAL
 * kexec is a system call that implements the ability to shutdown your current kernel, and to start another kernel. It is like a reboot but it is indepedent of the system firmware.   And like a reboot you can start any kernel with it, not just Linux.
 * The name comes from the similiarity to the exec system call.
 * It is an ongoing process to be certain the hardware in a machine is properly shutdown, so do not be surprised if this code does not initially work for you. It may help to enable device hotplugging support.  As of this writing the exact hardware interface is strongly in flux, so no good recommendation can be made.


 * Option: CRASH_DUMP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "kernel crash dumps (EXPERIMENTAL)"
 * depends on EMBEDDED
 * depends on EXPERIMENTAL
 * depends on HIGHMEM
 * Generate crash dump after being started by kexec.

Power management options (ACPI, APM)

 * depends on !X86_VOYAGER


 * Option: User:ZyMOS/Howto configure the linux kernel/kernel/power


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/acpi

APM (Advanced Power Management) BIOS Support

 * depends on PM && !X86_VISWS


 * Option: APM
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "APM (Advanced Power Management) BIOS support"
 * depends on PM && PM_LEGACY
 * APM is a BIOS specification for saving power using several different techniques. This is mostly useful for battery powered laptops with APM compliant BIOSes. If you say Y here, the system time will be reset after a RESUME operation, the /proc/apm device will provide battery status information, and user-space programs will receive notification of APM "events" (e.g. battery status change).
 * If you select "Y" here, you can disable actual use of the APM BIOS by passing the "apm=off" option to the kernel at boot time.
 * Note that the APM support is almost completely disabled for machines with more than one CPU.
 * In order to use APM, you will need supporting software. For location and more information, read  and the Battery Powered Linux mini-HOWTO, available from .
 * This driver does not spin down disk drives (see the hdparm(8) manpage ("man 8 hdparm") for that), and it doesn't turn off VESA-compliant "green" monitors.
 * This driver does not support the TI 4000M TravelMate and the ACER 486/DX4/75 because they don't have compliant BIOSes. Many "green" desktop machines also don't have compliant BIOSes, and this driver may cause those machines to panic during the boot phase.
 * Generally, if you don't have a battery in your machine, there isn't much point in using this driver and you should say N. If you get random kernel OOPSes or reboots that don't seem to be related to anything, try disabling/enabling this option (or disabling/enabling APM in your BIOS).
 * Some other things you should try when experiencing seemingly random, "weird" problems:
 * 1) make sure that you have enough swap space and that it is enabled. 2) pass the "no-hlt" option to the kernel 3) switch on floating point emulation in the kernel and pass the "no387" option to the kernel 4) pass the "floppy=nodma" option to the kernel 5) pass the "mem=4M" option to the kernel (thereby disabling all but the first 4 MB of RAM) 6) make sure that the CPU is not over clocked. 7) read the sig11 FAQ at  8) disable the cache from your BIOS settings 9) install a fan for the video card or exchange video RAM 10) install a better fan for the CPU 11) exchange RAM chips 12) exchange the motherboard.
 * To compile this driver as a module, choose M here: the module will be called apm.


 * Option: APM_IGNORE_USER_SUSPEND
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Ignore USER SUSPEND"
 * depends on APM
 * This option will ignore USER SUSPEND requests. On machines with a compliant APM BIOS, you want to say N. However, on the NEC Versa M series notebooks, it is necessary to say Y because of a BIOS bug.


 * Option: APM_DO_ENABLE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Enable PM at boot time"
 * depends on APM
 * Enable APM features at boot time. From page 36 of the APM BIOS specification: "When disabled, the APM BIOS does not automatically power manage devices, enter the Standby State, enter the Suspend State, or take power saving steps in response to CPU Idle calls." This driver will make CPU Idle calls when Linux is idle (unless this feature is turned off -- see "Do CPU IDLE calls", below). This should always save battery power, but more complicated APM features will be dependent on your BIOS implementation. You may need to turn this option off if your computer hangs at boot time when using APM support, or if it beeps continuously instead of suspending. Turn this off if you have a NEC UltraLite Versa 33/C or a Toshiba T400CDT. This is off by default since most machines do fine without this feature.


 * Option: APM_CPU_IDLE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Make CPU Idle calls when idle"
 * depends on APM
 * Enable calls to APM CPU Idle/CPU Busy inside the kernel's idle loop. On some machines, this can activate improved power savings, such as a slowed CPU clock rate, when the machine is idle. These idle calls are made after the idle loop has run for some length of time (e.g., 333 mS). On some machines, this will cause a hang at boot time or whenever the CPU becomes idle. (On machines with more than one CPU, this option does nothing.)


 * Option: APM_DISPLAY_BLANK
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Enable console blanking using APM"
 * depends on APM
 * Enable console blanking using the APM. Some laptops can use this to turn off the LCD backlight when the screen blanker of the Linux virtual console blanks the screen. Note that this is only used by the virtual console screen blanker, and won't turn off the backlight when using the X Window system. This also doesn't have anything to do with your VESA-compliant power-saving monitor. Further, this option doesn't work for all laptops -- it might not turn off your backlight at all, or it might print a lot of errors to the console, especially if you are using gpm.


 * Option: APM_RTC_IS_GMT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "RTC stores time in GMT"
 * depends on APM
 * Say Y here if your RTC (Real Time Clock a.k.a. hardware clock) stores the time in GMT (Greenwich Mean Time). Say N if your RTC stores localtime.
 * It is in fact recommended to store GMT in your RTC, because then you don't have to worry about daylight savings time changes. The only reason not to use GMT in your RTC is if you also run a broken OS that doesn't understand GMT.


 * Option: APM_ALLOW_INTS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Allow interrupts during APM BIOS calls"
 * depends on APM
 * Normally we disable external interrupts while we are making calls to the APM BIOS as a measure to lessen the effects of a badly behaving BIOS implementation. The BIOS should reenable interrupts if it needs to.  Unfortunately, some BIOSes do not -- especially those in many of the newer IBM Thinkpads.  If you experience hangs when you suspend, try setting this to Y.  Otherwise, say N.


 * Option: APM_REAL_MODE_POWER_OFF
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Use real mode APM BIOS call to power off"
 * depends on APM
 * Use real mode APM BIOS calls to switch off the computer. This is a work-around for a number of buggy BIOSes. Switch this option on if your computer crashes instead of powering off properly.


 * Option: User:ZyMOS/Howto configure the linux kernel/arch/i386/kernel/cpu/cpufreq

Bus options (PCI, PCMCIA, EISA, MCA, ISA)

 * Option: PCI
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "PCI support" if !X86_VISWS
 * depends on !X86_VOYAGER
 * default y if X86_VISWS
 * Find out whether you have a PCI motherboard. PCI is the name of a bus system, i.e. the way the CPU talks to the other stuff inside your box. Other bus systems are ISA, EISA, MicroChannel (MCA) or VESA. If you have PCI, say Y, otherwise N.
 * The PCI-HOWTO, available from , contains valuable information about which PCI hardware does work under Linux and which doesn't.

"PCI access mode"
 * depends on PCI && !X86_VISWS
 * default PCI_GOANY
 * On PCI systems, the BIOS can be used to detect the PCI devices and determine their configuration. However, some old PCI motherboards have BIOS bugs and may crash if this is done. Also, some embedded PCI-based systems don't have any BIOS at all. Linux can also try to detect the PCI hardware directly without using the BIOS.
 * With this option, you can specify how Linux should detect the PCI devices. If you choose "BIOS", the BIOS will be used, if you choose "Direct", the BIOS won't be used, and if you choose "MMConfig", then PCI Express MMCONFIG will be used. If you choose "Any", the kernel will try MMCONFIG, then the direct access method and falls back to the BIOS if that doesn't work. If unsure, go with the default, which is "Any".


 * Option: PCI_GOBIOS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "BIOS"


 * Option: PCI_GOMMCONFIG
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "MMConfig"


 * Option: PCI_GODIRECT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Direct"


 * Option: PCI_GOANY
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Any"


 * Option: PCI_BIOS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on !X86_VISWS && PCI && (PCI_GOBIOS || PCI_GOANY)
 * default y


 * Option: PCI_DIRECT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) depends on PCI && ((PCI_GODIRECT || PCI_GOANY) || X86_VISWS)
 * default y


 * Option: PCI_MMCONFIG
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
 * default y


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/pci/pcie


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/pci


 * Option: ISA_DMA_API
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: ISA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "ISA support"
 * depends on !(X86_VOYAGER || X86_VISWS)
 * Find out whether you have ISA slots on your motherboard. ISA is the name of a bus system, i.e. the way the CPU talks to the other stuff inside your box.  Other bus systems are PCI, EISA, MicroChannel (MCA) or VESA.  ISA is an older system, now being displaced by PCI; newer boards don't support it.  If you have ISA, say Y, otherwise N.


 * Option: EISA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "EISA support"
 * depends on ISA
 * The Extended Industry Standard Architecture (EISA) bus was developed as an open alternative to the IBM MicroChannel bus.
 * The EISA bus provided some of the features of the IBM MicroChannel bus while maintaining backward compatibility with cards made for the older ISA bus. The EISA bus saw limited use between 1988 and 1995 when it was made obsolete by the PCI bus.
 * Say Y here if you are building a kernel for an EISA-based machine.
 * Otherwise, say N.


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/eisa


 * Option: MCA
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "MCA support" if !(X86_VISWS || X86_VOYAGER)
 * default y if X86_VOYAGER
 * MicroChannel Architecture is found in some IBM PS/2 machines and laptops. It is a bus system similar to PCI or ISA. See <file:Documentation/mca.txt> (and especially the web page given there) before attempting to build an MCA bus kernel.


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/mca


 * Option: SCx200
 * Kernel Versions: 2.6.15.6 ...
 * (on/off/module) "NatSemi SCx200 support"
 * depends on !X86_VOYAGER
 * This provides basic support for the National Semiconductor SCx200 processor. Right now this is just a driver for the GPIO pins.
 * If you don't know what to do here, say N.
 * This support is also available as a module. If compiled as a module, it will be called scx200.


 * Option: HOTPLUG_CPU
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Support for hot-pluggable CPUs (EXPERIMENTAL)"
 * depends on SMP && HOTPLUG && EXPERIMENTAL
 * Say Y here to experiment with turning CPUs off and on. CPUs can be controlled through /sys/devices/system/cpu.
 * Say N.


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/pcmcia


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers/pci/hotplug

Executable file formats

 * Option: User:ZyMOS/Howto configure the linux kernel/fs.binfmt"


 * Option: User:ZyMOS/Howto configure the linux kernel/net


 * Option: User:ZyMOS/Howto configure the linux kernel/drivers


 * Option: User:ZyMOS/Howto configure the linux kernel/fs

Instrumentation Support

 * depends on EXPERIMENTAL


 * Option: User:ZyMOS/Howto configure the linux kernel/arch/i386/oprofile


 * Option: KPROBES
 * Kernel Versions: 2.6.15.6 ...
 * (on/off) "Kprobes (EXPERIMENTAL)"
 * Kprobes allows you to trap at almost any kernel address and execute a callback function. register_kprobe establishes a probepoint and specifies the callback.  Kprobes is useful for kernel debugging, non-intrusive instrumentation and testing. If in doubt, say "N".


 * Option: User:ZyMOS/Howto configure the linux kernel/arch/i386.debug"


 * Option: User:ZyMOS/Howto configure the linux kernel/security


 * Option: User:ZyMOS/Howto configure the linux kernel/crypto


 * Option: User:ZyMOS/Howto configure the linux kernel/lib


 * Use the generic interrupt handling code in kernel/irq/:
 * Use the generic interrupt handling code in kernel/irq/:


 * Option: GENERIC_HARDIRQS
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: GENERIC_IRQ_PROBE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * default y


 * Option: GENERIC_PENDING_IRQ
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on GENERIC_HARDIRQS && SMP
 * default y


 * Option: X86_SMP
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on SMP && !X86_VOYAGER
 * default y


 * Option: X86_HT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on SMP && !(X86_VISWS || X86_VOYAGER)
 * default y


 * Option: X86_BIOS_REBOOT
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on !(X86_VISWS || X86_VOYAGER)
 * default y


 * Option: X86_TRAMPOLINE
 * Kernel Versions: 2.6.15.6 ...
 * (on/off)
 * depends on X86_SMP || (X86_VOYAGER && SMP)
 * default y