Eric Lee / smarc-fsl-linux-kernel

14 Apr, 2011

4 commits

  • feddbb34e   UBI: fix minor stylistic issues ... Browse Code »

    Fix checkpatch.pl errors and warnings:

    * space before tab
    * line over 80 characters
    * include linux/ioctl.h instead of asm/ioctl.h

    Signed-off-by: Artem Bityutskiy

    Artem Bityutskiy
     
  • 3627924ac   UBI: use __packed instead of __attribute__((packed)) ... Browse Code »

    There was an attempt to standartize various "__attribute__" and
    other macros in order to have potentially portable and more
    consistent code, see commit 82ddcb040570411fc2d421d96b3e69711c670328.

    Note, that commit refers Rober Love's blog post, but the URL
    is broken, the valid URL is:
    http://blog.rlove.org/2005/10/with-little-help-from-your-compiler.html

    Moreover, nowadays checkpatch.pl warns about using
    __attribute__((packed)):

    "WARNING: __packed is preferred over __attribute__((packed))"

    It is not a big deal for UBI to use __packed, so let's do it.

    Signed-off-by: Artem Bityutskiy

    Artem Bityutskiy
     
  • e8e088de3   UBI: cleanup comments around volume properties ... Browse Code »

    Cleanup and improve commentaries around the "set volume properties" ioctl,
    make a simple indentation fix as well.

    Signed-off-by: Artem Bityutskiy

    Artem Bityutskiy
     
  • 6748482f4   UBI: re-name set volume properties ioctl ... Browse Code »

    Rename the ioctl which sets volume properties from 'UBI_IOCSETPROP' to
    'UBI_IOCSETVOLPROP' to reflect the fact that this ioctl is about volume
    properties, not device properties. This is also consistent with the
    other volume ioctl name - 'UBI_IOCVOLUP'.

    The main motivation for the re-name, however, is that we are going
    to introduce the per-UBI device "set properties" ioctl, so we need
    good and logical naming.

    At the same time, re-name the "set volume properties request" data
    structure from 'struct ubi_set_prop_req' to
    'struct ubi_set_vol_prop_req'.

    And re-name 'UBI_PROP_DIRECT_WRITE' to 'UBI_VOL_PROP_DIRECT_WRITE'.

    Signed-off-by: Artem Bityutskiy

    Artem Bityutskiy
     

09 Aug, 2010

1 commit

27 Mar, 2009

1 commit

27 Jan, 2009

1 commit

  • 766fb95ba   UBI: allow direct user-space I/O ... Browse Code »

    Introduce a new ioctl UBI_IOCSETPROP to set properties
    on a volume. Also add the first property:
    UBI_PROP_DIRECT_WRITE, this property is used to set the
    ability to use direct writes in userspace

    Signed-off-by: Sidney Amani
    Signed-off-by: Corentin Chary
    Signed-off-by: Artem Bityutskiy

    Sidney Amani
     

18 Jan, 2009

4 commits

06 Jan, 2009

1 commit

24 Jul, 2008

2 commits

25 Jan, 2008

1 commit

  • 866136827   UBI: introduce atomic LEB change ioctl ... Browse Code »

    We have to be able to change individual LEBs for utilities like
    ubifsck, ubifstune. For example, ubifsck has to be able to fix
    errors on the media, ubifstune has to be able to change the
    the superblock, hence this ioctl.

    Signed-off-by: Artem Bityutskiy

    Artem Bityutskiy
     

27 Dec, 2007

1 commit

27 Apr, 2007

1 commit

  • 801c135ce   UBI: Unsorted Block Images ... Browse Code »

    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
    Signed-off-by: Frank Haverkamp

    Artem B. Bityutskiy