http://howto.wikia.com/wiki/Howto_configure_the_Linux_kernel/Device_drivers/Memory_Technology_Devices_(MTD)
Howto configure the Linux kernel/Device
drivers/Memory Technology Devices (MTD)
From Wikihowto
Howto configure the Linux
kernel / drivers / mtd
- $Id: Kconfig,v 1.11 2005/11/07 11:14:19 gleixner Exp $
[edit]
Memory Technology Devices (MTD)
- Option: MTD
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) Memory Technology Device (MTD) support
- Memory Technology Devices are flash, RAM and similar
chips,
often used for solid state file systems on embedded devices. This
option will provide the generic support for MTD drivers to register
themselves with the kernel and for potential users of MTD devices to
enumerate the devices which are present and obtain a handle on them. It
will also allow you to select individual drivers for particular
hardware and users of MTD devices. If unsure, say N.
- Option: MTD_DEBUG
- Kernel Versions: 2.6.15.6 ...
- (on/off) Debugging
- depends on MTD
- This turns on low-level debugging for the entire MTD
sub-system. Normally, you should say 'N'.
- Option: MTD_DEBUG_VERBOSE
- Kernel Versions: 2.6.15.6 ...
"Debugging verbosity (0 = quiet, 3 = noisy)"
-
- depends on MTD_DEBUG
- default "0"
- Determines the verbosity level of the MTD debugging
messages.
- Option: MTD_CONCAT
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) MTD concatenating support
- depends on MTD
- Support for concatenating several MTD devices into a
single
(virtual) one. This allows you to have -for example- a JFFS(2) file
system spanning multiple physical flash chips. If unsure, say 'Y'.
- Option: MTD_PARTITIONS
- Kernel Versions: 2.6.15.6 ...
- (on/off) MTD partitioning support
- depends on MTD
- If you have a device which needs to divide its flash
chip(s)
up into multiple 'partitions', each of which appears to the user as a
separate MTD device, you require this option to be enabled. If unsure,
say 'Y'.
**: Note, however, that you don't need this option for the DiskOnChip
devices. Partitioning on NFTL 'devices' is a different - that's the
'normal' form of partitioning used on a block device.
- Option: MTD_REDBOOT_PARTS
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) RedBoot partition table parsing
- depends on MTD_PARTITIONS
- RedBoot is a ROM monitor and bootloader which deals with
multiple 'images' in flash devices by putting a table one of the erase
blocks on the device, similar to a partition table, which gives the
offsets, lengths and names of all the images stored in the flash.
**: If you need code which can detect and parse this table, and
register MTD 'partitions' corresponding to each image in the table,
enable this option.
**: You will still need the parsing functions to be called by the
driver for your particular device. It won't happen automatically. The
SA1100 map driver (CONFIG_MTD_SA1100) has an option for this, for
example.
- Option: MTD_REDBOOT_DIRECTORY_BLOCK
- Kernel Versions: 2.6.15.6 ...
"Location of RedBoot partition table"
-
- depends on MTD_REDBOOT_PARTS
- default "-1"
- This option is the Linux counterpart to the
CYGNUM_REDBOOT_FIS_DIRECTORY_BLOCK RedBoot compile time option.
**: The option specifies which Flash sectors holds the RedBoot
partition table. A zero or positive value gives an absolete erase block
number. A negative value specifies a number of sectors before the end
of the device.
**: For example "2" means block number 2, "-1" means the last block and
"-2" means the penultimate block.
- Option: MTD_REDBOOT_PARTS_UNALLOCATED
- Kernel Versions: 2.6.15.6 ...
- (on/off) Include unallocated flash regions
- depends on MTD_REDBOOT_PARTS
- If you need to register each unallocated flash region as
a MTD 'partition', enable this option.
- Option: MTD_REDBOOT_PARTS_READONLY
- Kernel Versions: 2.6.15.6 ...
- (on/off) Force read-only for RedBoot system images
- depends on MTD_REDBOOT_PARTS
- If you need to force read-only for 'RedBoot', 'RedBoot
Config' and 'FIS directory' images, enable this option.
- Option: MTD_CMDLINE_PARTS
- Kernel Versions: 2.6.15.6 ...
- (on/off) Command line partition table parsing
- depends on MTD_PARTITIONS = "y"
- Allow generic configuration of the MTD paritition tables
via
the kernel command line. Multiple flash resources are supported for
hardware where different kinds of flash memory are available.
**: You will still need the parsing functions to be called by the
driver for your particular device. It won't happen automatically. The
SA1100 map driver (CONFIG_MTD_SA1100) has an option for this, for
example.
**: The format for the command line is as follows:
**: mtdparts=<mtddef>[;<mtddef] <mtddef> :=
<mtd-id>:<partdef>[,<partdef>] <partdef> :=
<size>[EMAIL PROTECTED]<name>][ro] <mtd-id> := unique id
used in mapping driver/device <size> := standard linux memsize
OR "-" to denote all remaining space <name> := (NAME)
**: Due to the way Linux handles the command line, no spaces are
allowed in the partition definition, including mtd id's and partition
names.
**: Examples:
**: 1 flash resource (mtd-id "sa1100"), with 1 single writable
partition: mtdparts=sa1100:-
**: Same flash, but 2 named partitions, the first one being read-only:
mtdparts=sa1100:256k(ARMboot)ro,-(root)
**: If unsure, say 'N'.
- Option: MTD_AFS_PARTS
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) ARM Firmware Suite partition parsing
- depends on ARM && MTD_PARTITIONS
- The ARM Firmware Suite allows the user to divide flash
devices
into multiple 'images'. Each such image has a header containing its
name and offset/size etc.
**: If you need code which can detect and parse these tables, and
register MTD 'partitions' corresponding to each image detected, enable
this option.
**: You will still need the parsing functions to be called by the
driver for your particular device. It won't happen automatically. The
'armflash' map driver (CONFIG_MTD_ARMFLASH) does this, for example.
"User Modules And Translation Layers"
- Option: MTD_CHAR
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) Direct char device access to MTD devices
- depends on MTD
- This provides a character device for each MTD device
present
in the system, allowing the user to read and write directly to the
memory chips, and also use ioctl() to obtain information about the
device, or to erase parts of it.
- Option: MTD_BLOCK
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) Caching block device access to MTD devices
- depends on MTD
- Although most flash chips have an erase size too large
to be
useful as block devices, it is possible to use MTD devices which are
based on RAM chips in this manner. This block device is a user of MTD
devices performing that function.
**: At the moment, it is also required for the Journalling Flash File
System(s) to obtain a handle on the MTD device when it's mounted
(although JFFS and JFFS2 don't actually use any of the functionality of
the mtdblock device).
**: Later, it may be extended to perform read/erase/modify/write cycles
on flash chips to emulate a smaller block size. Needless to say, this
is very unsafe, but could be useful for file systems which are almost
never written to.
**: You do not need this option for use with the DiskOnChip devices.
For those, enable NFTL support (CONFIG_NFTL) instead.
- Option: MTD_BLOCK_RO
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) Readonly block device access to MTD
devices
- depends on MTD_BLOCK!=y && MTD
- This allows you to mount read-only file systems (such as
cramfs) from an MTD device, without the overhead (and danger) of the
caching driver.
**: You do not need this option for use with the DiskOnChip devices.
For those, enable NFTL support (CONFIG_NFTL) instead.
- Option: FTL
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) FTL (Flash Translation Layer) support
- depends on MTD
- This provides support for the original Flash Translation
Layer
which is part of the PCMCIA specification. It uses a kind of pseudo-
file system on a flash device to emulate a block device with 512-byte
sectors, on top of which you put a 'normal' file system.
**: You may find that the algorithms used in this code are patented
unless you live in the Free World where software patents aren't legal -
in the USA you are only permitted to use this on PCMCIA hardware,
although under the terms of the GPL you're obviously permitted to copy,
modify and distribute the code as you wish. Just not use it.
- Option: NFTL
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) NFTL (NAND Flash Translation Layer)
support
- depends on MTD
- This provides support for the NAND Flash Translation
Layer
which is used on M-Systems' DiskOnChip devices. It uses a kind of
pseudo- file system on a flash device to emulate a block device with
512-byte sectors, on top of which you put a 'normal' file system.
**: You may find that the algorithms used in this code are patented
unless you live in the Free World where software patents aren't legal -
in the USA you are only permitted to use this on DiskOnChip hardware,
although under the terms of the GPL you're obviously permitted to copy,
modify and distribute the code as you wish. Just not use it.
- Option: NFTL_RW
- Kernel Versions: 2.6.15.6 ...
- (on/off) Write support for NFTL
- depends on NFTL
- Support for writing to the NAND Flash Translation Layer,
as used on the DiskOnChip.
- Option: INFTL
- Kernel Versions: 2.6.15.6 ...
- (on/off/module) INFTL (Inverse NAND Flash Translation
Layer) support
- depends on MTD
- This provides support for the Inverse NAND Flash
Translation
Layer which is used on M-Systems' newer DiskOnChip devices. It uses a
kind of pseudo-file system on a flash device to emulate a block device
with 512-byte sectors, on top of which you put a 'normal' file system.
**: You may find that the algorithms used in this code are patented
unless you live in the Free World where software patents aren't legal -
in the USA you are only permitted to use this on DiskOnChip hardware,
although under the terms of the GPL you're obviously permitted to copy,
modify and distribute the code as you wish. Just not use it.
- Option: RFD_FTL
- Kernel Versions: 2.6.15.6 ... tristate Resident Flash
Disk (Flash Translation Layer) support
- depends on MTD
- This provides support for the flash translation layer
known as
the Resident Flash Disk (RFD), as used by the Embedded BIOS of General
Software. There is a blurb at:
- //www.gensw.com/pages/prod/bios/rfd.htm
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