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linux/drivers/mtd/Kconfig
David Howells 9361401eb7 [PATCH] BLOCK: Make it possible to disable the block layer [try #6] 
Make it possible to disable the block layer.  Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.

This patch does the following:

 (*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
     support.

 (*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
     an item that uses the block layer.  This includes:

     (*) Block I/O tracing.

     (*) Disk partition code.

     (*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.

     (*) The SCSI layer.  As far as I can tell, even SCSI chardevs use the
     	 block layer to do scheduling.  Some drivers that use SCSI facilities -
     	 such as USB storage - end up disabled indirectly from this.

     (*) Various block-based device drivers, such as IDE and the old CDROM
     	 drivers.

     (*) MTD blockdev handling and FTL.

     (*) JFFS - which uses set_bdev_super(), something it could avoid doing by
     	 taking a leaf out of JFFS2's book.

 (*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
     linux/elevator.h contingent on CONFIG_BLOCK being set.  sector_div() is,
     however, still used in places, and so is still available.

 (*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
     parts of linux/fs.h.

 (*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.

 (*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.

 (*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
     is not enabled.

 (*) fs/no-block.c is created to hold out-of-line stubs and things that are
     required when CONFIG_BLOCK is not set:

     (*) Default blockdev file operations (to give error ENODEV on opening).

 (*) Makes some /proc changes:

     (*) /proc/devices does not list any blockdevs.

     (*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.

 (*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.

 (*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
     given command other than Q_SYNC or if a special device is specified.

 (*) In init/do_mounts.c, no reference is made to the blockdev routines if
     CONFIG_BLOCK is not defined.  This does not prohibit NFS roots or JFFS2.

 (*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
     error ENOSYS by way of cond_syscall if so).

 (*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
     CONFIG_BLOCK is not set, since they can't then happen.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 20:52:31 +02:00

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# $Id: Kconfig,v 1.11 2005/11/07 11:14:19 gleixner Exp $
menu "Memory Technology Devices (MTD)"
config MTD
tristate "Memory Technology Device (MTD) support"
help
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.
config MTD_DEBUG
bool "Debugging"
depends on MTD
help
This turns on low-level debugging for the entire MTD sub-system.
Normally, you should say 'N'.
config MTD_DEBUG_VERBOSE
int "Debugging verbosity (0 = quiet, 3 = noisy)"
depends on MTD_DEBUG
default "0"
help
Determines the verbosity level of the MTD debugging messages.
config MTD_CONCAT
tristate "MTD concatenating support"
depends on MTD
help
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'.
config MTD_PARTITIONS
bool "MTD partitioning support"
depends on MTD
help
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.
config MTD_REDBOOT_PARTS
tristate "RedBoot partition table parsing"
depends on MTD_PARTITIONS
---help---
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.
config MTD_REDBOOT_DIRECTORY_BLOCK
int "Location of RedBoot partition table"
depends on MTD_REDBOOT_PARTS
default "-1"
---help---
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 absolute
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.
config MTD_REDBOOT_PARTS_UNALLOCATED
bool "Include unallocated flash regions"
depends on MTD_REDBOOT_PARTS
help
If you need to register each unallocated flash region as a MTD
'partition', enable this option.
config MTD_REDBOOT_PARTS_READONLY
bool "Force read-only for RedBoot system images"
depends on MTD_REDBOOT_PARTS
help
If you need to force read-only for 'RedBoot', 'RedBoot Config' and
'FIS directory' images, enable this option.
config MTD_CMDLINE_PARTS
bool "Command line partition table parsing"
depends on MTD_PARTITIONS = "y" && MTD = "y"
---help---
Allow generic configuration of the MTD partition 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>[@offset][<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'.
config MTD_AFS_PARTS
tristate "ARM Firmware Suite partition parsing"
depends on ARM && MTD_PARTITIONS
---help---
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.
comment "User Modules And Translation Layers"
depends on MTD
config MTD_CHAR
tristate "Direct char device access to MTD devices"
depends on MTD
help
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.
config MTD_BLOCK
tristate "Caching block device access to MTD devices"
depends on MTD && BLOCK
---help---
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.
config MTD_BLOCK_RO
tristate "Readonly block device access to MTD devices"
depends on MTD_BLOCK!=y && MTD && BLOCK
help
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.
config FTL
tristate "FTL (Flash Translation Layer) support"
depends on MTD && BLOCK
---help---
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.
config NFTL
tristate "NFTL (NAND Flash Translation Layer) support"
depends on MTD && BLOCK
---help---
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.
config NFTL_RW
bool "Write support for NFTL"
depends on NFTL
help
Support for writing to the NAND Flash Translation Layer, as used
on the DiskOnChip.
config INFTL
tristate "INFTL (Inverse NAND Flash Translation Layer) support"
depends on MTD && BLOCK
---help---
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.
config RFD_FTL
tristate "Resident Flash Disk (Flash Translation Layer) support"
depends on MTD && BLOCK
---help---
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:
http://www.gensw.com/pages/prod/bios/rfd.htm
config SSFDC
tristate "NAND SSFDC (SmartMedia) read only translation layer"
depends on MTD
default n
help
This enables read only access to SmartMedia formatted NAND
flash. You can mount it with FAT file system.
source "drivers/mtd/chips/Kconfig"
source "drivers/mtd/maps/Kconfig"
source "drivers/mtd/devices/Kconfig"
source "drivers/mtd/nand/Kconfig"
source "drivers/mtd/onenand/Kconfig"
endmenu
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