Commit graph

14 commits

Author SHA1 Message Date
Artem Bityutskiy
6e9065d756 UBI: add write checking
Add an extra debugging check function which validates writes.
After every write it reads the data back, compares it with the
original data, and complains if they mismatch.

Useful for debugging. No-op if extra debugging checks are disabled.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2010-02-01 15:16:37 +02:00
Artem Bityutskiy
867996b15c UBI: introduce flash dump helper
Useful for debugging problems, compiled in only if UBI debugging
is enabled. This patch also makes the UBI writing function dump
the flash if it fails to write.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2009-08-14 20:02:20 +03:00
Artem Bityutskiy
1398788fe7 UBI: remove bogus debugging checks
The 'paranoid_check_empty()' is bogus because, which is easilly
seen on NOR flash, which has long erase cycles, and which may
easilly end-up with half-erased eraseblocks. In this case the
paranoid check fails. I is just wrong to assume that PEBs which
do not have EC headers always contain all 0xFF. Such assumption
should not be made on the I/O level, which is quite low.

Thus, just kill the check.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2009-07-05 18:47:05 +03:00
Artem Bityutskiy
40a71a87fa UBI: add empty eraseblocks verification
This patch adds code which makes sure eraseblocks contain all 0xFF
bytes before starting using them. The verification is done only when
debugging checks are enabled.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2009-07-05 18:47:03 +03:00
Artem Bityutskiy
f2863c54f3 UBI: fix checkpatch.pl warnings
Just minor indentation and "over 80 characters" fixes.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-12-28 12:20:51 +02:00
Artem Bityutskiy
c8566350a3 UBI: fix and re-work debugging stuff
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24 13:34:45 +03:00
Artem Bityutskiy
85c6e6e282 UBI: amend commentaries
Hch asked not to use "unit" for sub-systems, let it be so.
Also some other commentaries modifications.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24 13:32:56 +03:00
David Woodhouse
e43fe686e4 Merge git://git.infradead.org/~dedekind/ubi-2.6 2008-04-23 09:57:25 +01:00
Harvey Harrison
cb53b3b999 [MTD] replace remaining __FUNCTION__ occurrences
__FUNCTION__ is gcc-specific, use __func__

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2008-04-22 12:36:04 +01:00
Artem Bityutskiy
a4f0fcdfb2 UBI: be verbose when debuggin is enabled
Make I/O function to be always verbose when about CRC errors
and magic number errors when I/O debugging is enabled.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-04-17 11:31:58 +03:00
Artem Bityutskiy
d19bafd99d UBI: add PID to debugging prints
Also, use single dbg_msg() macro for all prints.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:16 +02:00
Artem Bityutskiy
ef6075fbfc UBI: use linux print_hex_dump(), not home-grown one
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-10-14 13:10:20 +03:00
Artem Bityutskiy
94784d9164 UBI: bugfix in error path
When volume creation fails, we have to set ubi->volumes[vol_id]
back to NULL.

This patch also tweaks some debugging stuff.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:55:55 +03:00
Artem B. Bityutskiy
801c135ce7 UBI: Unsorted Block Images
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>
2007-04-27 14:23:33 +03:00