kconfig

Linux块设备驱动源码

          example) in your virtual machine, you will want to say Y here.  If
          you care for the safety of the data in your virtual machine, Y is a
          wise choice too.  In all other cases (for example, if you're just
          playing around with User-Mode Linux) you can choose N.

config BLK_DEV_COW_COMMON
	bool
	default BLK_DEV_UBD

config MMAPPER
	tristate "Example IO memory driver (BROKEN)"
	depends on UML && BROKEN
	---help---
          The User-Mode Linux port can provide support for IO Memory
          emulation with this option.  This allows a host file to be
          specified as an I/O region on the kernel command line. That file
          will be mapped into UML's kernel address space where a driver can
          locate it and do whatever it wants with the memory, including
          providing an interface to it for UML processes to use.

          For more information, see
          <http://user-mode-linux.sourceforge.net/iomem.html>.

          If you'd like to be able to provide a simulated IO port space for
          User-Mode Linux processes, say Y.  If unsure, say N.

config BLK_DEV_LOOP
	tristate "Loopback device support"
	---help---
	  Saying Y here will allow you to use a regular file as a block
	  device; you can then create a file system on that block device and
	  mount it just as you would mount other block devices such as hard
	  drive partitions, CD-ROM drives or floppy drives. The loop devices
	  are block special device files with major number 7 and typically
	  called /dev/loop0, /dev/loop1 etc.

	  This is useful if you want to check an ISO 9660 file system before
	  burning the CD, or if you want to use floppy images without first
	  writing them to floppy. Furthermore, some Linux distributions avoid
	  the need for a dedicated Linux partition by keeping their complete
	  root file system inside a DOS FAT file using this loop device
	  driver.

	  To use the loop device, you need the losetup utility, found in the
	  util-linux package, see
	  <ftp://ftp.kernel.org/pub/linux/utils/util-linux/>.

	  The loop device driver can also be used to "hide" a file system in
	  a disk partition, floppy, or regular file, either using encryption
	  (scrambling the data) or steganography (hiding the data in the low
	  bits of, say, a sound file). This is also safe if the file resides
	  on a remote file server.

	  There are several ways of encrypting disks. Some of these require
	  kernel patches. The vanilla kernel offers the cryptoloop option
	  and a Device Mapper target (which is superior, as it supports all
	  file systems). If you want to use the cryptoloop, say Y to both
	  LOOP and CRYPTOLOOP, and make sure you have a recent (version 2.12
	  or later) version of util-linux. Additionally, be aware that
	  the cryptoloop is not safe for storing journaled filesystems.

	  Note that this loop device has nothing to do with the loopback
	  device used for network connections from the machine to itself.

	  To compile this driver as a module, choose M here: the
	  module will be called loop.

	  Most users will answer N here.

config BLK_DEV_CRYPTOLOOP
	tristate "Cryptoloop Support"
	select CRYPTO
	depends on BLK_DEV_LOOP
	---help---
	  Say Y here if you want to be able to use the ciphers that are 
	  provided by the CryptoAPI as loop transformation. This might be
	  used as hard disk encryption.

	  WARNING: This device is not safe for journaled file systems like
	  ext3 or Reiserfs. Please use the Device Mapper crypto module
	  instead, which can be configured to be on-disk compatible with the
	  cryptoloop device.

config BLK_DEV_NBD
	tristate "Network block device support"
	depends on NET
	---help---
	  Saying Y here will allow your computer to be a client for network
	  block devices, i.e. it will be able to use block devices exported by
	  servers (mount file systems on them etc.). Communication between
	  client and server works over TCP/IP networking, but to the client
	  program this is hidden: it looks like a regular local file access to
	  a block device special file such as /dev/nd0.

	  Network block devices also allows you to run a block-device in
	  userland (making server and client physically the same computer,
	  communicating using the loopback network device).

	  Read <file:Documentation/nbd.txt> for more information, especially
	  about where to find the server code, which runs in user space and
	  does not need special kernel support.

	  Note that this has nothing to do with the network file systems NFS
	  or Coda; you can say N here even if you intend to use NFS or Coda.

	  To compile this driver as a module, choose M here: the
	  module will be called nbd.

	  If unsure, say N.

config BLK_DEV_SX8
	tristate "Promise SATA SX8 support"
	depends on PCI
	---help---
	  Saying Y or M here will enable support for the 
	  Promise SATA SX8 controllers.

	  Use devices /dev/sx8/$N and /dev/sx8/$Np$M.

config BLK_DEV_UB
	tristate "Low Performance USB Block driver"
	depends on USB
	help
	  This driver supports certain USB attached storage devices
	  such as flash keys.

	  Warning: Enabling this cripples the usb-storage driver.

	  If unsure, say N.

config BLK_DEV_RAM
	tristate "RAM disk support"
	---help---
	  Saying Y here will allow you to use a portion of your RAM memory as
	  a block device, so that you can make file systems on it, read and
	  write to it and do all the other things that you can do with normal
	  block devices (such as hard drives). It is usually used to load and
	  store a copy of a minimal root file system off of a floppy into RAM
	  during the initial install of Linux.

	  Note that the kernel command line option "ramdisk=XX" is now
	  obsolete. For details, read <file:Documentation/ramdisk.txt>.

	  To compile this driver as a module, choose M here: the
	  module will be called rd.

	  Most normal users won't need the RAM disk functionality, and can
	  thus say N here.

config BLK_DEV_RAM_COUNT
	int "Default number of RAM disks" if BLK_DEV_RAM
	default "16"
	help
	  The default value is 16 RAM disks. Change this if you know what
	  are doing. If you boot from a filesystem that needs to be extracted
	  in memory, you will need at least one RAM disk (e.g. root on cramfs).

config BLK_DEV_RAM_SIZE
	int "Default RAM disk size (kbytes)"
	depends on BLK_DEV_RAM
	default "4096"
	help
	  The default value is 4096 kilobytes. Only change this if you know
	  what are you doing. If you are using IBM S/390, then set this to
	  8192.

config BLK_DEV_INITRD
	bool "Initial RAM disk (initrd) support"
	depends on BLK_DEV_RAM=y
	help
	  The initial RAM disk is a RAM disk that is loaded by the boot loader
	  (loadlin or lilo) and that is mounted as root before the normal boot
	  procedure. It is typically used to load modules needed to mount the
	  "real" root file system, etc. See <file:Documentation/initrd.txt>
	  for details.


#XXX - it makes sense to enable this only for 32-bit subarch's, not for x86_64
#for instance.
config LBD
	bool "Support for Large Block Devices"
	depends on X86 || (MIPS && 32BIT) || PPC32 || ARCH_S390_31 || SUPERH || UML
	help
	  Say Y here if you want to attach large (bigger than 2TB) discs to
	  your machine, or if you want to have a raid or loopback device
	  bigger than 2TB.  Otherwise say N.

config CDROM_PKTCDVD
	tristate "Packet writing on CD/DVD media"
	depends on !UML
	help
	  If you have a CDROM drive that supports packet writing, say Y to
	  include preliminary support. It should work with any MMC/Mt Fuji
	  compliant ATAPI or SCSI drive, which is just about any newer CD
	  writer.

	  Currently only writing to CD-RW, DVD-RW and DVD+RW discs is possible.
	  DVD-RW disks must be in restricted overwrite mode.

	  To compile this driver as a module, choose M here: the
	  module will be called pktcdvd.

config CDROM_PKTCDVD_BUFFERS
	int "Free buffers for data gathering"
	depends on CDROM_PKTCDVD
	default "8"
	help
	  This controls the maximum number of active concurrent packets. More
	  concurrent packets can increase write performance, but also require
	  more memory. Each concurrent packet will require approximately 64Kb
	  of non-swappable kernel memory, memory which will be allocated at
	  pktsetup time.

config CDROM_PKTCDVD_WCACHE
	bool "Enable write caching"
	depends on CDROM_PKTCDVD
	help
	  If enabled, write caching will be set for the CD-R/W device. For now
	  this option is dangerous unless the CD-RW media is known good, as we
	  don't do deferred write error handling yet.

source "drivers/s390/block/Kconfig"

source "drivers/block/Kconfig.iosched"

config ATA_OVER_ETH
	tristate "ATA over Ethernet support"
	depends on NET
	help
	This driver provides Support for ATA over Ethernet block
	devices like the Coraid EtherDrive (R) Storage Blade.

endmenu