arch/i386/Config.help

CONFIG_SMP
  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 <file:Documentation/smp.tex>,
  <file:Documentation/smp.txt>, <file:Documentation/i386/IO-APIC.txt>,
  <file:Documentation/nmi_watchdog.txt> and the SMP-HOWTO available at
  <http://www.linuxdoc.org/docs.html#howto>.

  If you don't know what to do here, say N.

CONFIG_X86
  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.

CONFIG_MULTIQUAD
  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 Martin.Bligh@us.ibm.com

CONFIG_X86_UP_IOAPIC
  An IO-APIC (I/O Advanced Programmable Interrupt Controller) is an
  SMP-capable replacement for PC-style interrupt controllers. Most
  SMP systems and a small number of 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.

  If you have a system with several CPUs, you do not need to say Y
  here: the IO-APIC will be used automatically.

CONFIG_X86_UP_APIC
  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.

  If you have a system with several CPUs, you do not need to say Y
  here: the local APIC will be used automatically.

CONFIG_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 <file:arch/i386/math-emu/README>.

  If you are not sure, say Y; apart from resulting in a 66 KB bigger
  kernel, it won't hurt.

CONFIG_NOHIGHMEM
  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".

CONFIG_HIGHMEM4G
  Select this if you have a 32-bit processor and between 1 and 4
  gigabytes of physical RAM.

CONFIG_HIGHMEM64G
  Select this if you have a 32-bit processor and more than 4
  gigabytes of physical RAM.

CONFIG_IDE
  If you say Y here, your kernel will be able to manage low cost mass
  storage units such as ATA/(E)IDE and ATAPI units. The most common
  cases are IDE hard drives and ATAPI CD-ROM drives.

  If your system is pure SCSI and doesn't use these interfaces, you
  can say N here.

  Integrated Disk Electronics (IDE aka ATA-1) is a connecting standard
  for mass storage units such as hard disks. It was designed by
  Western Digital and Compaq Computer in 1984. It was then named
  ST506. Quite a number of disks use the IDE interface.

  AT Attachment (ATA) is the superset of the IDE specifications.
  ST506 was also called ATA-1.

  Fast-IDE is ATA-2 (also named Fast ATA), Enhanced IDE (EIDE) is
  ATA-3. It provides support for larger disks (up to 8.4GB by means of
  the LBA standard), more disks (4 instead of 2) and for other mass
  storage units such as tapes and cdrom. UDMA/33 (aka UltraDMA/33) is
  ATA-4 and provides faster (and more CPU friendly) transfer modes
  than previous PIO (Programmed processor Input/Output) from previous
  ATA/IDE standards by means of fast DMA controllers.

  ATA Packet Interface (ATAPI) is a protocol used by EIDE tape and
  CD-ROM drives, similar in many respects to the SCSI protocol.

  SMART IDE (Self Monitoring, Analysis and Reporting Technology) was
  designed in order to prevent data corruption and disk crash by
  detecting pre hardware failure conditions (heat, access time, and
  the like...). Disks built since June 1995 may follow this standard.
  The kernel itself don't manage this; however there are quite a
  number of user programs such as smart that can query the status of
  SMART parameters disk.

  If you want to compile this driver as a module ( = code which can be
  inserted in and removed from the running kernel whenever you want),
  say M here and read <file:Documentation/modules.txt>. The module
  will be called ide.o.

  For further information, please read <file:Documentation/ide.txt>.

  If unsure, say Y.

CONFIG_ISA
  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.

CONFIG_PCI
  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
  <http://www.linuxdoc.org/docs.html#howto>, contains valuable
  information about which PCI hardware does work under Linux and which
  doesn't.

CONFIG_PCI_GOBIOS
  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 "Any", the
  kernel will try the direct access method and falls back to the BIOS
  if that doesn't work. If unsure, go with the default, which is
  "Any".

CONFIG_HOTPLUG_PCI
  Say Y here if you have a motherboard with a PCI Hotplug controller.
  This allows you to add and remove PCI cards while the machine is
  powered up and running.  The file system pcihpfs must be mounted
  in order to interact with any PCI Hotplug controllers.

  This code is also available as a module ( = code which can be
  inserted in and removed from the running kernel whenever you want).
  The module will be called pci_hotplug.o. If you want to compile it
  as a module, say M here and read <file:Documentation/modules.txt>.

  When in doubt, say N.

CONFIG_MCA
  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.

CONFIG_EISA
  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.

CONFIG_VISWS
  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 other
  PC boards and vice versa.
  See <file:Documentation/sgi-visws.txt> for more.

CONFIG_HOTPLUG
  Say Y here if you want to plug devices into your computer while
  the system is running, and be able to use them quickly.  In many
  cases, the devices can likewise be unplugged at any time too.

  One well known example of this is PCMCIA- or PC-cards, credit-card
  size devices such as network cards, modems or hard drives which are
  plugged into slots found on all modern laptop computers.  Another
  example, used on modern desktops as well as laptops, is USB.

  Enable HOTPLUG and KMOD, and build a modular kernel.  Get agent
  software (at <http://linux-hotplug.sourceforge.net/>) and install it.
  Then your kernel will automatically call out to a user mode "policy
  agent" (/sbin/hotplug) to load modules and set up software needed
  to use devices as you hotplug them.

CONFIG_PCMCIA
  Say Y here if you want to attach PCMCIA- or PC-cards to your Linux
  computer.  These are credit-card size devices such as network cards,
  modems or hard drives often used with laptops computers.  There are
  actually two varieties of these cards: the older 16 bit PCMCIA cards
  and the newer 32 bit CardBus cards.  If you want to use CardBus
  cards, you need to say Y here and also to "CardBus support" below.

  To use your PC-cards, you will need supporting software from David
  Hinds' pcmcia-cs package (see the file <file:Documentation/Changes>
  for location).  Please also read the PCMCIA-HOWTO, available from
  <http://www.linuxdoc.org/docs.html#howto>.

  This driver is also available as a module ( = code which can be
  inserted in and removed from the running kernel whenever you want).
  When compiled this way, there will be modules called pcmcia_core.o
  and ds.o.  If you want to compile it as a module, say M here and
  read <file:Documentation/modules.txt>.

CONFIG_KCORE_ELF
  If you enabled support for /proc file system then the file
  /proc/kcore will contain the kernel core image. This can be used
  in gdb:

  $ cd /usr/src/linux ; gdb vmlinux /proc/kcore

  You have two choices here: ELF and A.OUT. Selecting ELF will make
  /proc/kcore appear in ELF core format as defined by the Executable
  and Linking Format specification. Selecting A.OUT will choose the
  old "a.out" format which may be necessary for some old versions
  of binutils or on some architectures.

  This is especially useful if you have compiled the kernel with the
  "-g" option to preserve debugging information. It is mainly used
  for examining kernel data structures on the live kernel so if you
  don't understand what this means or are not a kernel hacker, just
  leave it at its default value ELF.

CONFIG_KCORE_AOUT
  Not necessary unless you're using a very out-of-date binutils
  version.  You probably want KCORE_ELF.

CONFIG_BINFMT_ELF
  ELF (Executable and Linkable Format) is a format for libraries and
  executables used across different architectures and operating
  systems. Saying Y here will enable your kernel to run ELF binaries
  and enlarge it by about 13 KB. ELF support under Linux has now all
  but replaced the traditional Linux a.out formats (QMAGIC and ZMAGIC)
  because it is portable (this does *not* mean that you will be able
  to run executables from different architectures or operating systems
  however) and makes building run-time libraries very easy. Many new
  executables are distributed solely in ELF format. You definitely
  want to say Y here.

  Information about ELF is contained in the ELF HOWTO available from
  <http://www.linuxdoc.org/docs.html#howto>.

  If you find that after upgrading from Linux kernel 1.2 and saying Y
  here, you still can't run any ELF binaries (they just crash), then
  you'll have to install the newest ELF runtime libraries, including
  ld.so (check the file <file:Documentation/Changes> for location and
  latest version).

  If you want to compile this as a module ( = code which can be
  inserted in and removed from the running kernel whenever you want),
  say M here and read <file:Documentation/modules.txt>.  The module
  will be called binfmt_elf.o. Saying M or N here is dangerous because
  some crucial programs on your system might be in ELF format.

CONFIG_BINFMT_AOUT
  A.out (Assembler.OUTput) is a set of formats for libraries and
  executables used in the earliest versions of UNIX. Linux used the
  a.out formats QMAGIC and ZMAGIC until they were replaced with the
  ELF format.

  As more and more programs are converted to ELF, the use for a.out
  will gradually diminish. If you disable this option it will reduce
  your kernel by one page. This is not much and by itself does not
  warrant removing support. However its removal is a good idea if you
  wish to ensure that absolutely none of your programs will use this
  older executable format. If you don't know what to answer at this
  point then answer Y. If someone told you "You need a kernel with
  QMAGIC support" then you'll have to say Y here. You may answer M to
  compile a.out support as a module and later load the module when you
  want to use a program or library in a.out format. The module will be
  called binfmt_aout.o. Saying M or N here is dangerous though,
  because some crucial programs on your system might still be in A.OUT
  format.

CONFIG_BINFMT_MISC
  If you say Y here, it will be possible to plug wrapper-driven binary
  formats into the kernel. You will like this especially when you use
  programs that need an interpreter to run like Java, Python or
  Emacs-Lisp. It's also useful if you often run DOS executables under
  the Linux DOS emulator DOSEMU (read the DOSEMU-HOWTO, available from
  <http://www.linuxdoc.org/docs.html#howto>). Once you have
  registered such a binary class with the kernel, you can start one of
  those programs simply by typing in its name at a shell prompt; Linux
  will automatically feed it to the correct interpreter.

  You can do other nice things, too. Read the file
  <file:Documentation/binfmt_misc.txt> to learn how to use this
  feature, and <file:Documentation/java.txt> for information about how
  to include Java support.

  You must say Y to "/proc file system support" (CONFIG_PROC_FS) to
  use this part of the kernel.

  You may say M here for module support and later load the module when
  you have use for it; the module is called binfmt_misc.o. If you
  don't know what to answer at this point, say Y.

CONFIG_M386
  This is the processor type of your CPU. This information is used for
  optimizing purposes. In order to compile a kernel that can run on
  all x86 CPU types (albeit not optimally fast), you can specify
  "386" here.

  The kernel will not necessarily run on earlier architectures than
  the one you have chosen, e.g. a Pentium optimized kernel will run on
  a PPro, but not necessarily on a i486.

  Here are the settings recommended for greatest speed:
   - "386" for the AMD/Cyrix/Intel 386DX/DXL/SL/SLC/SX, Cyrix/TI
     486DLC/DLC2, UMC 486SX-S and NexGen Nx586.  Only "386" kernels
     will run on a 386 class machine.
   - "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
     SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
   - "586" for generic Pentium CPUs lacking the TSC
     (time stamp counter) register.
   - "Pentium-Classic" for the Intel Pentium.
   - "Pentium-MMX" for the Intel Pentium MMX.
   - "Pentium-Pro" for the Intel Pentium Pro/Celeron/Pentium II.
   - "Pentium-III" for the Intel Pentium III
     and Celerons based on the Coppermine core.
   - "Pentium-4" for the Intel Pentium 4.
   - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
   - "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
   - "Crusoe" for the Transmeta Crusoe series.
   - "Winchip-C6" for original IDT Winchip.
   - "Winchip-2" for IDT Winchip 2.
   - "Winchip-2A" for IDT Winchips with 3dNow! capabilities.
   - "CyrixIII" for VIA Cyrix III or VIA C3.

  If you don't know what to do, choose "386".

CONFIG_M486
  Select this for a x486 processor, ether Intel or one of the
  compatible processors from AMD, Cyrix, IBM, or Intel.  Includes DX,
  DX2, and DX4 variants; also SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or
  U5S.

CONFIG_M586
  Select this for an x586 or x686 processor such as the AMD K5, the
  Intel 5x86 or 6x86, or the Intel 6x86MX.  This choice does not
  assume the RDTSC (Read Time Stamp Counter) instruction.

CONFIG_M586TSC
  Select this for a Pentium Classic processor with the RDTSC (Read
  Time Stamp Counter) instruction for benchmarking.

CONFIG_M586MMX
  Select this for a Pentium with the MMX graphics/multimedia
  extended instructions.

CONFIG_M686
  Select this for a Pro/Celeron/Pentium II.  This enables the use of
  Pentium Pro extended instructions, and disables the init-time guard
  against the f00f bug found in earlier Pentiums.

CONFIG_MPENTIUMIII
  Select this for Intel chips based on the Pentium-III and
  Celeron-Coppermine core.  Enables use of some extended prefetch
  instructions, in addition to the Pentium II extensions.

CONFIG_MPENTIUM4
  Select this for Intel Pentium 4 chips.  Presently these are
  treated almost like Pentium IIIs, but with a different cache
  shift.

CONFIG_MCRUSOE
  Select this for Transmeta Crusoe processor.  Treats the processor
  like a 586 with TSC, and sets some GCC optimization flags (like a
  Pentium Pro with no alignment requirements).

CONFIG_MK6
  Select this for an AMD K6-family processor.  Enables use of
  some extended instructions, and passes appropriate optimization
  flags to GCC.

CONFIG_MK7
  Select this for an AMD Athlon K7-family processor.  Enables use of
  some extended instructions, and passes appropriate optimization
  flags to GCC.

CONFIG_MCYRIXIII
  Select this for a Cyrix III or C3 chip.  Presently Linux and GCC
  treat this chip as a generic 586. Whilst the CPU is 686 class,
  it lacks the cmov extension which gcc assumes is present when
  generating 686 code.

CONFIG_MWINCHIPC6
  Select this for a IDT Winchip C6 chip.  Linux and GCC
  treat this chip as a 586TSC with some extended instructions
  and alignment requirements.

CONFIG_MWINCHIP2
  Select this for a IDT Winchip-2.  Linux and GCC
  treat this chip as a 586TSC with some extended instructions
  and alignment requirements.

CONFIG_MWINCHIP3D
  Select this for a IDT Winchip-2A or 3.  Linux and GCC
  treat this chip as a 586TSC with some extended instructions
  and alignment reqirements.  Development kernels also enable
  out of order memory stores for this CPU, which can increase
  performance of some operations.

CONFIG_VGA_CONSOLE
  Saying Y here will allow you to use Linux in text mode through a
  display that complies with the generic VGA standard. Virtually
  everyone wants that.

  The program SVGATextMode can be used to utilize SVGA video cards to
  their full potential in text mode. Download it from
  <ftp://ibiblio.org/pub/Linux/utils/console/>.

  Say Y.

CONFIG_VIDEO_SELECT
  This enables support for text mode selection on kernel startup. If
  you want to take advantage of some high-resolution text mode your
  card's BIOS offers, but the traditional Linux utilities like
  SVGATextMode don't, you can say Y here and set the mode using the
  "vga=" option from your boot loader (lilo or loadlin) or set
  "vga=ask" which brings up a video mode menu on kernel startup. (Try
  "man bootparam" or see the documentation of your boot loader about
  how to pass options to the kernel.)

  Read the file <file:Documentation/svga.txt> for more information
  about the Video mode selection support. If unsure, say N.

CONFIG_MDA_CONSOLE
  Say Y here if you have an old MDA or monochrome Hercules graphics
  adapter in your system acting as a second head ( = video card). You
  will then be able to use two monitors with your Linux system. Do not
  say Y here if your MDA card is the primary card in your system; the
  normal VGA driver will handle it.

  This driver is also available as a module ( = code which can be
  inserted and removed from the running kernel whenever you want).
  The module will be called mdacon.o. If you want to compile it as
  a module, say M here and read <file:Documentation/modules.txt>.

  If unsure, say N.

CONFIG_SCSI
  If you want to use a SCSI hard disk, SCSI tape drive, SCSI CD-ROM or
  any other SCSI device under Linux, say Y and make sure that you know
  the name of your SCSI host adapter (the card inside your computer
  that "speaks" the SCSI protocol, also called SCSI controller),
  because you will be asked for it.

  You also need to say Y here if you want support for the parallel
  port version of the 100 MB IOMEGA ZIP drive.

  This driver is also available as a module ( = code which can be
  inserted in and removed from the running kernel whenever you want).
  The module will be called scsi_mod.o.  If you want to compile it as
  a module, say M here and read <file:Documentation/modules.txt> and
  <file:Documentation/scsi.txt>.  However, do not compile this as a
  module if your root file system (the one containing the directory /)
  is located on a SCSI device.

CONFIG_NETDEVICES
  You can say N here if you don't intend to connect your Linux box to
  any other computer at all or if all your connections will be over a
  telephone line with a modem either via UUCP (UUCP is a protocol to
  forward mail and news between unix hosts over telephone lines; read
  the UUCP-HOWTO, available from
  <http://www.linuxdoc.org/docs.html#howto>) or dialing up a shell
  account or a BBS, even using term (term is a program which gives you
  almost full Internet connectivity if you have a regular dial up
  shell account on some Internet connected Unix computer. Read
  <http://www.bart.nl/~patrickr/term-howto/Term-HOWTO.html>).

  You'll have to say Y if your computer contains a network card that
  you want to use under Linux (make sure you know its name because you
  will be asked for it and read the Ethernet-HOWTO (especially if you
  plan to use more than one network card under Linux)) or if you want
  to use SLIP (Serial Line Internet Protocol is the protocol used to
  send Internet traffic over telephone lines or null modem cables) or
  CSLIP (compressed SLIP) or PPP (Point to Point Protocol, a better
  and newer replacement for SLIP) or PLIP (Parallel Line Internet
  Protocol is mainly used to create a mini network by connecting the
  parallel ports of two local machines) or AX.25/KISS (protocol for
  sending Internet traffic over amateur radio links).

  Make sure to read the NET-3-HOWTO. Eventually, you will have to read
  Olaf Kirch's excellent and free book "Network Administrator's
  Guide", to be found in <http://www.linuxdoc.org/docs.html#guide>. If
  unsure, say Y.

CONFIG_CD_NO_IDESCSI
  If you have a CD-ROM drive that is neither SCSI nor IDE/ATAPI, say Y
  here, otherwise N. Read the CD-ROM-HOWTO, available from
  <http://www.linuxdoc.org/docs.html#howto>.

  Note that the answer to this question doesn't directly affect the
  kernel: saying N will just cause the configurator to skip all
  the questions about these CD-ROM drives. If you are unsure what you
  have, say Y and find out whether you have one of the following
  drives.

  For each of these drivers, a file Documentation/cdrom/{driver_name}
  exists. Especially in cases where you do not know exactly which kind
  of drive you have you should read there. Most of these drivers use a
  file drivers/cdrom/{driver_name}.h where you can define your
  interface parameters and switch some internal goodies.

  All these CD-ROM drivers are also usable as a module ( = code which
  can be inserted in and removed from the running kernel whenever you
  want). If you want to compile them as module, say M instead of Y and
  read <file:Documentation/modules.txt>.

  If you want to use any of these CD-ROM drivers, you also have to
  answer Y or M to "ISO 9660 CD-ROM file system support" below (this
  answer will get "defaulted" for you if you enable any of the Linux
  CD-ROM drivers).

CONFIG_MTRR
  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 <file:Documentation/mtrr.txt> for more information.

CONFIG_PM
  "Power Management" means that parts of your computer are shut
  off or put into a power conserving "sleep" mode if they are not
  being used.  There are two competing standards for doing this: APM
  and ACPI.  If you want to use either one, say Y here and then also
  to the requisite support below.

  Power Management is most important for battery powered laptop
  computers; if you have a laptop, check out the Linux Laptop home
  page on the WWW at
  <http://www.cs.utexas.edu/users/kharker/linux-laptop/> and the
  Battery Powered Linux mini-HOWTO, available from
  <http://www.linuxdoc.org/docs.html#howto>.

  Note that, even if you say N here, Linux on the x86 architecture
  will issue the hlt instruction if nothing is to be done, thereby
  sending the processor to sleep and saving power.

CONFIG_ACPI
  ACPI/OSPM support for Linux is currently under development. As such,
  this support is preliminary and EXPERIMENTAL.  Configuring ACPI
  support enables kernel interfaces that allow higher level software
  (OSPM) to manipulate ACPI defined hardware and software interfaces,
  including the evaluation of ACPI control methods.  If unsure, choose
  N here.  Note, this option will enlarge your kernel by about 120K.

  This support requires an ACPI compliant platform (hardware/firmware).
  If both ACPI and Advanced Power Management (APM) support are
  configured, whichever is loaded first shall be used.

  This code DOES NOT currently provide a complete OSPM implementation
  -- it has not yet reached APM's level of functionality.  When fully
  implemented, Linux ACPI/OSPM will provide a more robust functional
  replacement for legacy configuration and power management
  interfaces, including the Plug-and-Play BIOS specification (PnP
  BIOS), the Multi-Processor Specification (MPS), and the Advanced
  Power Management specification (APM).

  Linux support for ACPI/OSPM is based on Intel Corporation's ACPI
  Component Architecture (ACPI CA). The latest ACPI CA source code,
  documentation, debug builds, and implementation status information
  can be downloaded from:
  <http://developer.intel.com/technology/iapc/acpi/downloads.htm>.

  The ACPI Sourceforge project may also be of interest:
  <http://sf.net/projects/acpi/>

CONFIG_APM
  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 <file:Documentation/pm.txt> and the
  Battery Powered Linux mini-HOWTO, available from
  <http://www.linuxdoc.org/docs.html#howto>.

  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 <http://www.bitwizard.nl/sig11/>
   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 ( = code which can be inserted in
  and removed from the running kernel whenever you want), say M here
  and read <file:Documentation/modules.txt>. The module will be called
  apm.o.

CONFIG_APM_IGNORE_USER_SUSPEND
  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.

CONFIG_APM_DO_ENABLE
  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.

CONFIG_APM_CPU_IDLE
  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.)

CONFIG_APM_DISPLAY_BLANK
  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.

CONFIG_APM_RTC_IS_GMT
  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.

CONFIG_APM_ALLOW_INTS
  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.

CONFIG_APM_REAL_MODE_POWER_OFF
  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.

CONFIG_TOSHIBA
  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 Pheonix 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:
  <http://www.buzzard.org.uk/toshiba/>.

  Say Y if you intend to run this kernel on a Toshiba portable.
  Say N otherwise.

CONFIG_I8K
  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:
  <http://www.debian.org/~dz/i8k/>

  Say Y if you intend to run this kernel on a Dell Inspiron 8000.
  Say N otherwise.

CONFIG_MICROCODE
  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:
  <http://www.urbanmyth.org/microcode/>.

  This driver is also available as a module ( = code which can be
  inserted in and removed from the running kernel whenever you want).
  The module will be called microcode.o.  If you want to compile it as
  a module, say M here and read <file:Documentation/modules.txt>.  If
  you use modprobe or kmod you may also want to add the line
  'alias char-major-10-184 microcode' to your /etc/modules.conf file.

CONFIG_X86_MSR
  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.

CONFIG_X86_CPUID
  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.

CONFIG_SOUND
  If you have a sound card in your computer, i.e. if it can say more
  than an occasional beep, say Y.  Be sure to have all the information
  about your sound card and its configuration down (I/O port,
  interrupt and DMA channel), because you will be asked for it.

  You want to read the Sound-HOWTO, available from
  <http://www.linuxdoc.org/docs.html#howto>. General information about
  the modular sound system is contained in the files
  <file:Documentation/sound/Introduction>.  The file
  <file:Documentation/sound/README.OSS> contains some slightly
  outdated but still useful information as well.

  If you have a PnP sound card and you want to configure it at boot
  time using the ISA PnP tools (read
  <http://www.roestock.demon.co.uk/isapnptools/>), then you need to
  compile the sound card support as a module ( = code which can be
  inserted in and removed from the running kernel whenever you want)
  and load that module after the PnP configuration is finished.  To do
  this, say M here and read <file:Documentation/modules.txt> as well
  as <file:Documentation/sound/README.modules>; the module will be
  called soundcore.o.

  I'm told that even without a sound card, you can make your computer
  say more than an occasional beep, by programming the PC speaker.
  Kernel patches and supporting utilities to do that are in the pcsp
  package, available at <ftp://ftp.infradead.org/pub/pcsp/>.

CONFIG_MAGIC_SYSRQ
  If you say Y here, you will have some control over the system even
  if the system crashes for example during kernel debugging (e.g., you
  will be able to flush the buffer cache to disk, reboot the system
  immediately or dump some status information). This is accomplished
  by pressing various keys while holding SysRq (Alt+PrintScreen). It
  also works on a serial console (on PC hardware at least), if you
  send a BREAK and then within 5 seconds a command keypress. The
  keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
  unless you really know what this hack does.

CONFIG_ISDN
  ISDN ("Integrated Services Digital Networks", called RNIS in France)
  is a special type of fully digital telephone service; it's mostly
  used to connect to your Internet service provider (with SLIP or
  PPP).  The main advantage is that the speed is higher than ordinary
  modem/telephone connections, and that you can have voice
  conversations while downloading stuff.  It only works if your
  computer is equipped with an ISDN card and both you and your service
  provider purchased an ISDN line from the phone company.  For
  details, read <http://alumni.caltech.edu/~dank/isdn/> on the WWW.

  This driver allows you to use an ISDN-card for networking
  connections and as dialin/out device.  The isdn-tty's have a built
  in AT-compatible modem emulator.  Network devices support autodial,
  channel-bundling, callback and caller-authentication without having
  a daemon running.  A reduced T.70 protocol is supported with tty's
  suitable for German BTX.  On D-Channel, the protocols EDSS1
  (Euro-ISDN) and 1TR6 (German style) are supported.  See
  <file:Documentation/isdn/README> for more information.

  If you want to compile the ISDN code as a module ( = code which can
  be inserted in and removed from the running kernel whenever you
  want), say M here and read <file:Documentation/modules.txt>.  The
  module will be called isdn.o. If unsure, say N.

CONFIG_DEBUG_HIGHMEM
  This options enables addition error checking for high memory systems.
  Disable for production systems.

CONFIG_DEBUG_KERNEL
  Say Y here if you are developing drivers or trying to debug and
  identify kernel problems.

CONFIG_DEBUG_SLAB
  Say Y here to have the kernel do limited verification on memory
  allocation as well as poisoning memory on free to catch use of freed
  memory.

CONFIG_DEBUG_IOVIRT
  Say Y here to get warned whenever an attempt is made to do I/O on
  obviously invalid addresses such as those generated when ioremap()
  calls are forgotten.  Memory mapped I/O will go through an extra
  check to catch access to unmapped ISA addresses, an access method
  that can still be used by old drivers that are being ported from
  2.0/2.2.

CONFIG_DEBUG_SPINLOCK
  Say Y here and build SMP to catch missing spinlock initialization
  and certain other kinds of spinlock errors commonly made.  This is
  best used in conjunction with the NMI watchdog so that spinlock
  deadlocks are also debuggable.

CONFIG_DEBUG_BUGVERBOSE
  Say Y here to make BUG() panics output the file name and line number
  of the BUG call as well as the EIP and oops trace.  This aids
  debugging but costs about 70-100K of memory.