Make this option a hidden one and get a cleaner configuration.
This option just selects a common infrastructure for MTD-based devices
to expose a block interface. There is no point in allowing a separate
enable/disable.
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
[Brian: keep symbol as tristate]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
The MTD subsystem has historically tried to be as configurable as possible. The
side-effect of this is that its configuration menu is rather large, and we are
gradually shrinking it. For example, we recently merged partitions support with
the mtdcore.
This patch does the next step - it merges the mtdchar module to mtdcore. And in
this case this is not only about eliminating too fine-grained separation and
simplifying the configuration menu. This is also about eliminating seemingly
useless kernel module.
Indeed, mtdchar is a module that allows user-space making use of MTD devices
via /dev/mtd* character devices. If users do not enable it, they simply cannot
use MTD devices at all. They cannot read or write the flash contents. Is it a
sane and useful setup? I believe not. And everyone just enables mtdchar.
Having mtdchar separate is also a little bit harmful. People sometimes miss the
fact that they need to enable an additional configuration option to have
user-space MTD interfaces, and then they wonder why on earth the kernel does
not allow using the flash? They spend time asking around.
Thus, let's just get rid of this module and make it part of mtd core.
Note, mtdchar had additional configuration option to enable OTP interfaces,
which are present on some flashes. I removed that option as well - it saves a
really tiny amount space.
[dwmw2: Strictly speaking, you can mount file systems on MTD devices just
fine without the mtdchar (or mtdblock) devices; you just can't do
other manipulations directly on the underlying device. But still I
agree that it makes sense to make this unconditional. And Yay! we
get to kill off an instance of checking CONFIG_foo_MODULE, which is
an abomination that should never happen.]
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
* misc clean-ups in the MTD command-line partitioning parser (cmdlinepart)
* add flash locking support for STmicro chips serial flash chips, as well as
for CFI command set 2 chips.
* new driver for the ELM error correction HW module found in various TI chips,
enable the OMAP NAND driver to use the ELM HW error correction
* added number of new serial flash IDs
* various fixes and improvements in the gpmi NAND driver
* bcm47xx NAND driver improvements
* make the mtdpart module actually removable
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Merge tag 'for-linus-20130301' of git://git.infradead.org/linux-mtd
Pull MTD update from David Woodhouse:
"Fairly unexciting MTD merge for 3.9:
- misc clean-ups in the MTD command-line partitioning parser
(cmdlinepart)
- add flash locking support for STmicro chips serial flash chips, as
well as for CFI command set 2 chips.
- new driver for the ELM error correction HW module found in various
TI chips, enable the OMAP NAND driver to use the ELM HW error
correction
- added number of new serial flash IDs
- various fixes and improvements in the gpmi NAND driver
- bcm47xx NAND driver improvements
- make the mtdpart module actually removable"
* tag 'for-linus-20130301' of git://git.infradead.org/linux-mtd: (45 commits)
mtd: map: BUG() in non handled cases
mtd: bcm47xxnflash: use pr_fmt for module prefix in messages
mtd: davinci_nand: Use managed resources
mtd: mtd_torturetest can cause stack overflows
mtd: physmap_of: Convert device allocation to managed devm_kzalloc()
mtd: at91: atmel_nand: for PMECC, add code to check the ONFI parameter ECC requirement.
mtd: atmel_nand: make pmecc-cap, pmecc-sector-size in dts is optional.
mtd: atmel_nand: avoid to report an error when lookup table offset is 0.
mtd: bcm47xxsflash: adjust names of bus-specific functions
mtd: bcm47xxpart: improve probing of nvram partition
mtd: bcm47xxpart: add support for other erase sizes
mtd: bcm47xxnflash: register this as normal driver
mtd: bcm47xxnflash: fix message
mtd: bcm47xxsflash: register this as normal driver
mtd: bcm47xxsflash: write number of written bytes
mtd: gpmi: add sanity check for the ECC
mtd: gpmi: set the Golois Field bit for mx6q's BCH
mtd: devices: elm: Removes <xx> literals in elm DT node
mtd: gpmi: fix a dereferencing freed memory error
mtd: fix the wrong timeo for panic_nand_wait()
...
All other partitioning schemes can be compiled as modules
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
The CONFIG_EXPERIMENTAL config item has not carried much meaning for a
while now and is almost always enabled by default. As agreed during the
Linux kernel summit, remove it from any "depends on" lines in Kconfigs.
CC: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
This driver provides parser detecting partitions on BCM47XX flash
memories. It has many differences in comparison to BCM63XX, like:
1) Different CFE with no more trivial MAGICs
2) More partitions types (board_data, ML, POT)
3) Supporting more than 1 flash on a device
which resulted in decision of writing new parser.
It uses generic mtd interface and was successfully tested with Netgear
WNDR4500 router which has 2 flash memories: serial one and NAND one.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
MTD_OF_PARTS and the default setting is not working due to using 'Y'
instead of 'y', introduced in commit
d6137badef. This made our board, and
possibly other boards using DTS defined partitions and not having
CONFIG_MTD_OF_PARTS=y defined in the defconfig, fail to mount root.
Signed-off-by: Frank Svendsboe <frank.svendsboe@gmail.com>
Cc: stable@kernel.org [3.2+]
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Artem's cleanup of the MTD API continues apace.
Fixes and improvements for ST FSMC and SuperH FLCTL NAND, amongst others.
More work on DiskOnChip G3, new driver for DiskOnChip G4.
Clean up debug/warning printks in JFFS2 to use pr_<level>.
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Merge tag 'for-linus-3.4' of git://git.infradead.org/mtd-2.6
Pull MTD changes from David Woodhouse:
- Artem's cleanup of the MTD API continues apace.
- Fixes and improvements for ST FSMC and SuperH FLCTL NAND, amongst
others.
- More work on DiskOnChip G3, new driver for DiskOnChip G4.
- Clean up debug/warning printks in JFFS2 to use pr_<level>.
Fix up various trivial conflicts, largely due to changes in calling
conventions for things like dmaengine_prep_slave_sg() (new inline
wrapper to hide new parameter, clashing with rewrite of previously last
parameter that used to be an 'append' flag, and is now a bitmap of
'unsigned long flags').
(Also some header file fallout - like so many merges this merge window -
and silly conflicts with sparse fixes)
* tag 'for-linus-3.4' of git://git.infradead.org/mtd-2.6: (120 commits)
mtd: docg3 add protection against concurrency
mtd: docg3 refactor cascade floors structure
mtd: docg3 increase write/erase timeout
mtd: docg3 fix inbound calculations
mtd: nand: gpmi: fix function annotations
mtd: phram: fix section mismatch for phram_setup
mtd: unify initialization of erase_info->fail_addr
mtd: support ONFI multi lun NAND
mtd: sm_ftl: fix typo in major number.
mtd: add device-tree support to spear_smi
mtd: spear_smi: Remove default partition information from driver
mtd: Add device-tree support to fsmc_nand
mtd: fix section mismatch for doc_probe_device
mtd: nand/fsmc: Remove sparse warnings and errors
mtd: nand/fsmc: Add DMA support
mtd: nand/fsmc: Access the NAND device word by word whenever possible
mtd: nand/fsmc: Use dev_err to report error scenario
mtd: nand/fsmc: Use devm routines
mtd: nand/fsmc: Modify fsmc driver to accept nand timing parameters via platform
mtd: fsmc_nand: add pm callbacks to support hibernation
...
The mtdoops usage instructions found in Kconfig have been incorrect
since:
commit 2e386e4bac
mtd: mtdoops: refactor as a kmsg_dumper
mtdoops no longer uses a console. Now, if you build it into your kernel,
you add something like the following to your command line to select
partition X as your logging partition:
mtdoops.mtddev=X
Anyway, it seems better to leave the documentation out of Kconfig.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
CONFIG_GENERIC_IO is just enough for the basic MTD stuff.
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Recent BCM63XX devices support a variety of flash types (parallel, SPI,
NAND) and share the partition layout. To prevent code duplication make
the CFE partition parsing code a stand alone mtd parser to allow SPI or
NAND flash drivers to use it.
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Acked-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
* git://git.infradead.org/mtd-2.6: (226 commits)
mtd: tests: annotate as DANGEROUS in Kconfig
mtd: tests: don't use mtd0 as a default
mtd: clean up usage of MTD_DOCPROBE_ADDRESS
jffs2: add compr=lzo and compr=zlib options
jffs2: implement mount option parsing and compression overriding
mtd: nand: initialize ops.mode
mtd: provide an alias for the redboot module name
mtd: m25p80: don't probe device which has status of 'disabled'
mtd: nand_h1900 never worked
mtd: Add DiskOnChip G3 support
mtd: m25p80: add EON flash EN25Q32B into spi flash id table
mtd: mark block device queue as non-rotational
mtd: r852: make r852_pm_ops static
mtd: m25p80: add support for at25df321a spi data flash
mtd: mxc_nand: preset_v1_v2: unlock all NAND flash blocks
mtd: nand: switch `check_pattern()' to standard `memcmp()'
mtd: nand: invalidate cache on unaligned reads
mtd: nand: do not scan bad blocks with NAND_BBT_NO_OOB set
mtd: nand: wait to set BBT version
mtd: nand: scrub BBT on ECC errors
...
Fix up trivial conflicts:
- arch/arm/mach-at91/board-usb-a9260.c
Merged into board-usb-a926x.c
- drivers/mtd/maps/lantiq-flash.c
add_mtd_partitions -> mtd_device_register vs changed to use
mtd_device_parse_register.
The tests may erase mtd devices, so annotate them as suggested per
coding style and add a paragraph to the help text as well.
Artem: amended the help test a bit.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@intel.com>
There are numerous broken references to Documentation files (in other
Documentation files, in comments, etc.). These broken references are
caused by typo's in the references, and by renames or removals of the
Documentation files. Some broken references are simply odd.
Fix these broken references, sometimes by dropping the irrelevant text
they were part of.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
As ofpart now uses a standard mtd partitions parser interface, make it
buildable as a separate module. Also provide MODULE_DESCRIPTION and
MODULE_AUTHOR for this module.
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Artem Bityutskiy <dedekind1@gmail.com>
* git://git.infradead.org/mtd-2.6: (97 commits)
mtd: kill CONFIG_MTD_PARTITIONS
mtd: remove add_mtd_partitions, add_mtd_device and friends
mtd: convert remaining users to mtd_device_register()
mtd: samsung onenand: convert to mtd_device_register()
mtd: omap2 onenand: convert to mtd_device_register()
mtd: txx9ndfmc: convert to mtd_device_register()
mtd: tmio_nand: convert to mtd_device_register()
mtd: socrates_nand: convert to mtd_device_register()
mtd: sharpsl: convert to mtd_device_register()
mtd: s3c2410 nand: convert to mtd_device_register()
mtd: ppchameleonevb: convert to mtd_device_register()
mtd: orion_nand: convert to mtd_device_register()
mtd: omap2: convert to mtd_device_register()
mtd: nomadik_nand: convert to mtd_device_register()
mtd: ndfc: convert to mtd_device_register()
mtd: mxc_nand: convert to mtd_device_register()
mtd: mpc5121_nfc: convert to mtd_device_register()
mtd: jz4740_nand: convert to mtd_device_register()
mtd: h1910: convert to mtd_device_register()
mtd: fsmc_nand: convert to mtd_device_register()
...
Fixed up trivial conflicts in
- drivers/mtd/maps/integrator-flash.c: removed in ARM tree
- drivers/mtd/maps/physmap.c: addition of afs partition probe type
clashing with removal of CONFIG_MTD_PARTITIONS
Now that none of the drivers use CONFIG_MTD_PARTITIONS we can remove
it from Kconfig and the last remaining uses.
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
There are very few situations where MTD partitioning is not required,
and the benefit in code size reduction by making this configurable does
not warrant the level of ifdeffery needed.
Artem: this patch is not final - we just make sure that mtd partitions
are always compiled in, and at the end of the series we'll kill
MTD_PARTITIONS altogether.
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
As there is now no in-tree user of integrator-flash, remove
it completely.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Acked-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
As Artem Bityutskiy suggested: this option is controversial, as we
do not really have any prove it is useful. And it is too much to have
it as a config parameter. So, better kill it and let the real mtdswap
users decide whether it is needed or not.
Signed-off-by: Yang Ruirui<ruirui.r.yang@tieto.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Add a driver for allowing an mtd device to be used as a block device for
swapping. The block device is volatile, and the mapping of swapped pages
is not stored on flash.
Signed-off-by: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
As there are no more dependencies on MTD_CONCAT or CONFIG_MTD_CONCAT,
drop this entry from Kconfig entirely.
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Move mtdconcat to be an integral part of the mtd core. It's a tiny bit
of code, which bears 'say Y if you don't know what to do' note in the
Kconfig. OTOH there are several ugly ifdefs depending on the MTD_CONCAT.
So, making MTD_CONCAT support mandatory will allow us to clean up code a
lot.
Kconfig entry is changed to be a bool defaulting to Y, so all code
pieces depending on it, will have MTD_CONCAT Kconfig symbol and
CONFIG_MTD_CONCAT define. This will be removed in one of next patches.
Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
MTD_OF_PARTS should be possible on all architectures, not just
powerpc and microblaze, and it probably should not be a user
selectable option. Neither does it need to be in a separate module.
Also, rework MTD Kconfig to group options dependant on MTD_PARTITIONS
into a if/endif block. Do the same for MTD_REDBOOT_PARTS.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
I think that scary description can go now...
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Look for dependency checks for "FOO" when inside of an "if FOO" block and remove them.
Signed-off-by: Kyle Spaans <kspaans@uwaterloo.ca>
Reviewed-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
The sole purpose of this setting was to avoid a dependency on MTD_NAND.
Now that we can depend on MTD_NAND_ECC without pulling in all the rest
of the NAND code, we might as well do so unconditionally.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This way drivers could use ecc routines without depedency on whole nand
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Randy Dunlap observed a build problem with the following config:
CONFIG_SM_FTL=y
CONFIG_SM_FTL_MUSEUM=y
CONFIG_MTD_NAND=m
The ECC calculation routines are then built as a module, but referenced
by the sm_ftl code in the kernel, resulting in a build failure. The
simple fix is to make CONFIG_SM_FTL depend on MTD_NAND unconditionally
-- it's pointless without hardware support anyway.
Fix some typos which Randy pointed out, too.
Reported-By: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This implements new readwrite SmartMedia/xd FTL.
mtd driver must have support proper ECC and badblock verification
based on oob parts for 512 bytes nand.
Also mtd driver must define read_oob and write_oob, which are used
to read and write both data and oob together.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
* 'for-linus' of git://git.monstr.eu/linux-2.6-microblaze: (24 commits)
microblaze: Disable heartbeat/enable emaclite in defconfigs
microblaze: Support simpleImage.dts make target
microblaze: Fix _start symbol to physical address
microblaze: Use LOAD_OFFSET macro to get correct LMA for all sections
microblaze: Create the LOAD_OFFSET macro used to compute VMA vs LMA offsets
microblaze: Copy ppc asm-compat.h for clean handling of constants in asm and C
microblaze: Actually show KiB rather than pages in "Freeing initrd memory:"
microblaze: Support ptrace syscall tracing.
microblaze: Updated CPU version and FPGA family codes in PVR
microblaze: Generate correct signal and siginfo for integer div-by-zero
microblaze: Don't be noisy when userspace causes hardware exceptions
microblaze: Remove ipc.h file which points to non-existing asm-generic file
microblaze: Clear sticky FSR register after generating exception signals
microblaze: Ensure CPU usermode is set on new userspace processes
microblaze: Use correct kbuild variable KBUILD_CFLAGS
microblaze: Save and restore msr in hw exception
microblaze: Add architectural support for USB EHCI host controllers
microblaze: Implement include/asm/syscall.h.
microblaze: Improve checking mechanism for MSR instruction
microblaze: Add checking mechanism for MSR instruction
...
The MTD_TEST config option was added in between the MTD_PARTITIONS config
and its dependent options which causes the resulting menu system to
display incorrectly as MTD_TEST does not depend on MTD_PARTITIONS. So
move it up a few lines where it won't cause a problem.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
The real 'armflash' map driver is selected by CONFIG_MTD_ARM_INTEGRATOR
Signed-off-by: Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
We have two components to manage LPDDR flash memories in Linux.
1. It is a driver for chip probing and reading its capabilities
2. It is a device operations driver.
Signed-off-by: Alexey Korolev <akorolev@infradead.org>
Acked-by: Jared Hulbert <jaredeh@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Now that we can tell when we have one of the newer DataFlash chips,
optionally expose the 128 bytes of OTP memory they provide. Tested
on at45db642 revision B and D chips.
Switch mtdchar over to a generic HAVE_MTD_OTP flag instead of adding
another #ifdef for each type of chip whose driver has OTP support.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Bryan Wu <cooloney@kernel.org>
Cc: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Once upon a time, the MTD repository was using CVS.
This patch therefore removes all usages of the no longer updated CVS
keywords from the MTD code.
This also includes code that printed them to the user.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Add usage instructions to Kconfig for mtdoops driver.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Kernel oops and panic messages are invaluable when debugging crashes.
These messages often don't make it to flash based logging methods (say a
syslog on jffs2) due to the overheads involved in writing to flash.
This patch allows you to turn an MTD partition into a circular log
buffer where kernel oops and panic messages are written to. The messages
are obtained by registering a console driver and checking
oops_in_progress. Erases are performed in advance to maximise the
chances of a saving messages.
To activate it, add console=ttyMTDx to the kernel commandline (where x
is the mtd device number to use).
Signed-off-by: Richard Purdie <rpurdie@openedhand.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Add "depends on HAS_IOMEM" to a number of menus to make them
disappear for s390 which does not have I/O memory.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
UBI (Latin: "where?") manages multiple logical volumes on a single
flash device, specifically supporting NAND flash devices. UBI provides
a flexible partitioning concept which still allows for wear-levelling
across the whole flash device.
In a sense, UBI may be compared to the Logical Volume Manager
(LVM). Whereas LVM maps logical sector numbers to physical HDD sector
numbers, UBI maps logical eraseblocks to physical eraseblocks.
More information may be found at
http://www.linux-mtd.infradead.org/doc/ubi.html
Partitioning/Re-partitioning
An UBI volume occupies a certain number of erase blocks. This is
limited by a configured maximum volume size, which could also be
viewed as the partition size. Each individual UBI volume's size can
be changed independently of the other UBI volumes, provided that the
sum of all volume sizes doesn't exceed a certain limit.
UBI supports dynamic volumes and static volumes. Static volumes are
read-only and their contents are protected by CRC check sums.
Bad eraseblocks handling
UBI transparently handles bad eraseblocks. When a physical
eraseblock becomes bad, it is substituted by a good physical
eraseblock, and the user does not even notice this.
Scrubbing
On a NAND flash bit flips can occur on any write operation,
sometimes also on read. If bit flips persist on the device, at first
they can still be corrected by ECC, but once they accumulate,
correction will become impossible. Thus it is best to actively scrub
the affected eraseblock, by first copying it to a free eraseblock
and then erasing the original. The UBI layer performs this type of
scrubbing under the covers, transparently to the UBI volume users.
Erase Counts
UBI maintains an erase count header per eraseblock. This frees
higher-level layers (like file systems) from doing this and allows
for centralized erase count management instead. The erase counts are
used by the wear-levelling algorithm in the UBI layer. The algorithm
itself is exchangeable.
Booting from NAND
For booting directly from NAND flash the hardware must at least be
capable of fetching and executing a small portion of the NAND
flash. Some NAND flash controllers have this kind of support. They
usually limit the window to a few kilobytes in erase block 0. This
"initial program loader" (IPL) must then contain sufficient logic to
load and execute the next boot phase.
Due to bad eraseblocks, which may be randomly scattered over the
flash device, it is problematic to store the "secondary program
loader" (SPL) statically. Also, due to bit-flips it may become
corrupted over time. UBI allows to solve this problem gracefully by
storing the SPL in a small static UBI volume.
UBI volumes vs. static partitions
UBI volumes are still very similar to static MTD partitions:
* both consist of eraseblocks (logical eraseblocks in case of UBI
volumes, and physical eraseblocks in case of static partitions;
* both support three basic operations - read, write, erase.
But UBI volumes have the following advantages over traditional
static MTD partitions:
* there are no eraseblock wear-leveling constraints in case of UBI
volumes, so the user should not care about this;
* there are no bit-flips and bad eraseblocks in case of UBI volumes.
So, UBI volumes may be considered as flash devices with relaxed
restrictions.
Where can it be found?
Documentation, kernel code and applications can be found in the MTD
gits.
What are the applications for?
The applications help to create binary flash images for two purposes: pfi
files (partial flash images) for in-system update of UBI volumes, and plain
binary images, with or without OOB data in case of NAND, for a manufacturing
step. Furthermore some tools are/and will be created that allow flash content
analysis after a system has crashed..
Who did UBI?
The original ideas, where UBI is based on, were developed by Andreas
Arnez, Frank Haverkamp and Thomas Gleixner. Josh W. Boyer and some others
were involved too. The implementation of the kernel layer was done by Artem
B. Bityutskiy. The user-space applications and tools were written by Oliver
Lohmann with contributions from Frank Haverkamp, Andreas Arnez, and Artem.
Joern Engel contributed a patch which modifies JFFS2 so that it can be run on
a UBI volume. Thomas Gleixner did modifications to the NAND layer. Alexander
Schmidt made some testing work as well as core functionality improvements.
Signed-off-by: Artem B. Bityutskiy <dedekind@linutronix.de>
Signed-off-by: Frank Haverkamp <haver@vnet.ibm.com>
Use menuconfigs instead of menus, so the whole menu can be disabled at once
instead of going through all options.
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Add a MTD_BLKDEVS Kconfig option to cleanup the makefile a bit
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Artem Bityutskiy <dedekind@infradead.org>
This patch fixes the following compile error with
CONFIG_SSFDC=m, CONFIG_BLOCK=n:
<-- snip -->
...
CC [M] drivers/mtd/mtd_blkdevs.o
/home/bunk/linux/kernel-2.6/git/linux-2.6/drivers/mtd/mtd_blkdevs.c:40: warning: ‘struct request’ declared inside parameter list
/home/bunk/linux/kernel-2.6/git/linux-2.6/drivers/mtd/mtd_blkdevs.c:40: warning: its scope is only this definition or declaration, which is probably not what you want
/home/bunk/linux/kernel-2.6/git/linux-2.6/drivers/mtd/mtd_blkdevs.c: In function ‘do_blktrans_request’:
/home/bunk/linux/kernel-2.6/git/linux-2.6/drivers/mtd/mtd_blkdevs.c:45: error: dereferencing pointer to incomplete type
...
make[3]: *** [drivers/mtd/mtd_blkdevs.o] Error 1
<-- snip -->
Bug report by Jesper Juhl.
This patch also removes a pointless "default n" from the SSFDC option.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Ezequiel Garcia