Howto configure the Linux kernel / drivers / block

Block device driver configuration

Block devices

  • Option: BLK_DEV_FD
    • Kernel Versions: ...
    • (on/off/module) Normal floppy disk support
    • depends on ARCH_MAY_HAVE_PC_FDC
      If you want to use the floppy disk drive(s) of your PC under Linux, say Y. Information about this driver, especially important for IBM Thinkpad users, is contained in <file:Documentation/floppy.txt>. That file also contains the location of the Floppy driver FAQ as well as location of the fdutils package used to configure additional parameters of the driver at run time.
      To compile this driver as a module, choose M here: the module will be called floppy.

  • Option: AMIGA_FLOPPY
    • Kernel Versions: ...
    • (on/off/module) Amiga floppy support
    • depends on AMIGA

  • Option: ATARI_FLOPPY
    • Kernel Versions: ...
    • (on/off/module) Atari floppy support
    • depends on ATARI

  • Option: BLK_DEV_SWIM_IOP
    • Kernel Versions: ...
    • (on/off) Macintosh IIfx/Quadra 900/Quadra 950 floppy support (EXPERIMENTAL)
    • depends on MAC && EXPERIMENTAL && BROKEN
      Say Y here to support the SWIM (Super Woz Integrated Machine) IOP floppy controller on the Macintosh IIfx and Quadra 900/950.

  • Option: MAC_FLOPPY
    • Kernel Versions: ...
    • (on/off/module) Support for PowerMac floppy
    • depends on PPC_PMAC && !PPC_PMAC64
      If you have a SWIM-3 (Super Woz Integrated Machine 3; from Apple) floppy controller, say Y here. Most commonly found in PowerMacs.

  • Option: BLK_DEV_PS2
    • Kernel Versions: ...
    • (on/off/module) PS/2 ESDI hard disk support
    • depends on MCA && MCA_LEGACY && BROKEN
      Say Y here if you have a PS/2 machine with a MCA bus and an ESDI hard disk.
      To compile this driver as a module, choose M here: the module will be called ps2esdi.

  • Option: AMIGA_Z2RAM
    • Kernel Versions: ...
    • (on/off/module) Amiga Zorro II ramdisk support
    • depends on ZORRO
      This enables support for using Chip RAM and Zorro II RAM as a ramdisk or as a swap partition. Say Y if you want to include this driver in the kernel.
      To compile this driver as a module, choose M here: the module will be called z2ram.

  • Option: ATARI_ACSI
    • Kernel Versions: ...
    • (on/off/module) Atari ACSI support
    • depends on ATARI && BROKEN
      This enables support for the Atari ACSI interface. The driver supports hard disks and CD-ROMs, which have 512-byte sectors, or can be switched to that mode. Due to the ACSI command format, only disks up to 1 GB are supported. Special support for certain ACSI to SCSI adapters, which could relax that, isn't included yet. The ACSI driver is also the basis for certain other drivers for devices attached to the ACSI bus: Atari SLM laser printer, BioNet-100 Ethernet, and PAMsNet Ethernet. If you want to use one of these devices, you need ACSI support, too.
      To compile this driver as a module, choose M here: the module will be called acsi.

"Some devices (e.g. CD jukebox) support multiple LUNs"

    • depends on ATARI && ATARI_ACSI

  • Option: ACSI_MULTI_LUN
    • Kernel Versions: ...
    • (on/off) Probe all LUNs on each ACSI device
    • depends on ATARI_ACSI
      If you have an ACSI device that supports more than one LUN (Logical Unit Number), e.g. a CD jukebox, you should say Y here so that all will be found by the ACSI driver. An ACSI device with multiple LUNs acts logically like multiple ACSI devices. The vast majority of ACSI devices have only one LUN, and so most people can say N here and should in fact do so, because it is safer.

  • Option: ATARI_SLM
    • Kernel Versions: ...
    • (on/off/module) Atari SLM laser printer support
    • depends on ATARI && ATARI_ACSI!=n
      If you have an Atari SLM laser printer, say Y to include support for it in the kernel. Otherwise, say N. 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 acsi_slm. Be warned: the driver needs much ST-RAM and can cause problems due to that fact!

  • Option: BLK_DEV_XD
    • Kernel Versions: ...
    • (on/off/module) XT hard disk support
    • depends on ISA && ISA_DMA_API
      Very old 8 bit hard disk controllers used in the IBM XT computer will be supported if you say Y here.
      To compile this driver as a module, choose M here: the module will be called xd.
      It's pretty unlikely that you have one of these: say N.

  • Option: PARIDE
    • Kernel Versions: ...
    • (on/off/module) Parallel port IDE device support
    • depends on PARPORT
      There are many external CD-ROM and disk devices that connect through your computer's parallel port. Most of them are actually IDE devices using a parallel port IDE adapter. This option enables the PARIDE subsystem which contains drivers for many of these external drives. Read <file:Documentation/paride.txt> for more information.
      If you have said Y to the "Parallel-port support" configuration option, you may share a single port between your printer and other parallel port devices. Answer Y to build PARIDE support into your kernel, or M if you would like to build it as a loadable module. If your parallel port support is in a loadable module, you must build PARIDE as a module. If you built PARIDE support into your kernel, you may still build the individual protocol modules and high-level drivers as loadable modules. If you build this support as a module, it will be called paride.
      To use the PARIDE support, you must say Y or M here and also to at least one high-level driver (e.g. "Parallel port IDE disks", Parallel port ATAPI CD-ROMs, Parallel port ATAPI disks etc.) and to at least one protocol driver (e.g. "ATEN EH-100 protocol", MicroSolutions backpack protocol, DataStor Commuter protocol etc.).

  • Option: BLK_CPQ_DA
    • Kernel Versions: ...
    • (on/off/module) Compaq SMART2 support
    • depends on PCI
      This is the driver for Compaq Smart Array controllers. Everyone using these boards should say Y here. See the file <file:Documentation/cpqarray.txt> for the current list of boards supported by this driver, and for further information on the use of this driver.

  • Option: BLK_CPQ_CISS_DA
    • Kernel Versions: ...
    • (on/off/module) Compaq Smart Array 5xxx support
    • depends on PCI
      This is the driver for Compaq Smart Array 5xxx controllers. Everyone using these boards should say Y here. See <file:Documentation/cciss.txt> for the current list of boards supported by this driver, and for further information on the use of this driver.

  • Option: CISS_SCSI_TAPE
    • Kernel Versions: ...
    • (on/off) SCSI tape drive support for Smart Array 5xxx
    • depends on BLK_CPQ_CISS_DA && SCSI && PROC_FS
      When enabled (Y), this option allows SCSI tape drives and SCSI medium changers (tape robots) to be accessed via a Compaq 5xxx array controller. (See <file:Documentation/cciss.txt> for more details.)
      SCSI support and SCSI tape support must also be enabled for this option to work.
      When this option is disabled (N), the SCSI portion of the driver is not compiled.

  • Option: BLK_DEV_DAC960
    • Kernel Versions: ...
    • (on/off/module) Mylex DAC960/DAC1100 PCI RAID Controller support
    • depends on PCI
      This driver adds support for the Mylex DAC960, AcceleRAID, and eXtremeRAID PCI RAID controllers. See the file <file:Documentation/README.DAC960> for further information about this driver.
      To compile this driver as a module, choose M here: the module will be called DAC960.

  • Option: BLK_DEV_UMEM
    • Kernel Versions: ...
    • (on/off/module) Micro Memory MM5415 Battery Backed RAM support (EXPERIMENTAL)
    • depends on PCI && EXPERIMENTAL
      Saying Y here will include support for the MM5415 family of battery backed (Non-volatile) RAM cards. <>
      The cards appear as block devices that can be partitioned into as many as 15 partitions.
      To compile this driver as a module, choose M here: the module will be called umem.
      The umem driver has not yet been allocated a MAJOR number, so one is chosen dynamically. Use "devfs" or look in /proc/devices for the device number

  • Option: BLK_DEV_UBD
    • Kernel Versions: ...
    • (on/off) Virtual block device
    • depends on UML
      The User-Mode Linux port includes a driver called UBD which will let you access arbitrary files on the host computer as block devices. Unless you know that you do not need such virtual block devices say Y here.

  • Option: BLK_DEV_UBD_SYNC
    • Kernel Versions: ...
    • (on/off) Always do synchronous disk IO for UBD
    • depends on BLK_DEV_UBD
      Writes to the virtual block device are not immediately written to the host's disk; this may cause problems if, for example, the User-Mode Linux 'Virtual Machine' uses a journalling filesystem and the host computer crashes.
      Synchronous operation (i.e. always writing data to the host's disk immediately) is configurable on a per-UBD basis by using a special kernel command line option. Alternatively, you can say Y here to turn on synchronous operation by default for all block devices.
      If you're running a journalling file system (like reiserfs, for 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.

    • Kernel Versions: ...
    • (on/off)
    • default BLK_DEV_UBD

  • Option: MMAPPER
    • Kernel Versions: ...
    • (on/off/module) Example IO memory driver (BROKEN)
    • depends on UML && BROKEN
      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 <>.
      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.

  • Option: BLK_DEV_LOOP
    • Kernel Versions: ...
    • (on/off/module) Loopback device support
      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 <>.
      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.

    • Kernel Versions: ...
    • (on/off/module) Cryptoloop Support
    • select CRYPTO
    • depends on BLK_DEV_LOOP
      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.

  • Option: BLK_DEV_NBD
    • Kernel Versions: ...
    • (on/off/module) Network block device support
    • depends on NET
      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.

  • Option: BLK_DEV_SX8
    • Kernel Versions: ...
    • (on/off/module) Promise SATA SX8 support
    • depends on PCI
      Saying Y or M here will enable support for the Promise SATA SX8 controllers.
      Use devices /dev/sx8/$N and /dev/sx8/$Np$M.

  • Option: BLK_DEV_UB
    • Kernel Versions: ...
    • (on/off/module) Low Performance USB Block driver
    • depends on USB
      This driver supports certain USB attached storage devices such as flash keys.
      Warning: Enabling this cripples the USB-storage driver.
      If unsure, say N.

  • Option: BLK_DEV_RAM
    • Kernel Versions: ...
    • (on/off/module) RAM disk support
      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.

    • Kernel Versions: ...

"Default number of RAM disks" if BLK_DEV_RAM

    • default "16"
      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).

  • Option: BLK_DEV_RAM_SIZE
    • Kernel Versions: ...

"Default RAM disk size (kbytes)"

    • depends on BLK_DEV_RAM
    • default "4096"
      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.

  • Option: BLK_DEV_INITRD
    • Kernel Versions: ...
    • (on/off) Initial RAM disk (initrd) support
    • depends on BLK_DEV_RAM=y
      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.

    • Kernel Versions: ...
    • (on/off/module) Packet writing on CD/DVD media
    • depends on !UML
      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.

    • Kernel Versions: ...

"Free buffers for data gathering"

    • depends on CDROM_PKTCDVD
    • default "8"
      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.

    • Kernel Versions: ...
    • (on/off) Enable write caching
    • depends on CDROM_PKTCDVD
      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.

  • Option: ATA_OVER_ETH
    • Kernel Versions: ...
    • (on/off/module) ATA over Ethernet support
    • depends on NET

driver provides Support for ATA over Ethernet block like the Coraid EtherDrive (R) Storage Blade.

Linux Kernel Configuration

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