diff options
author | Andrei Warkentin <andreiw@motorola.com> | 2011-04-11 19:10:25 -0400 |
---|---|---|
committer | Chris Ball <cjb@laptop.org> | 2011-05-24 21:01:21 -0400 |
commit | 371a689f64b0da140c3bcd3f55305ffa1c3a58ef (patch) | |
tree | c0dff82d668378d395cb22ce33cd93e6dafef9eb /Documentation/mmc/mmc-dev-parts.txt | |
parent | 1a258db6f396e26c2c00b19c0107a891895d4584 (diff) |
mmc: MMC boot partitions support.
Allows device MMC boot partitions to be accessed. MMC partitions are
treated effectively as separate block devices on the same MMC card.
Signed-off-by: Andrei Warkentin <andreiw@motorola.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'Documentation/mmc/mmc-dev-parts.txt')
-rw-r--r-- | Documentation/mmc/mmc-dev-parts.txt | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/Documentation/mmc/mmc-dev-parts.txt b/Documentation/mmc/mmc-dev-parts.txt new file mode 100644 index 00000000000..2db28b8e662 --- /dev/null +++ b/Documentation/mmc/mmc-dev-parts.txt | |||
@@ -0,0 +1,27 @@ | |||
1 | SD and MMC Device Partitions | ||
2 | ============================ | ||
3 | |||
4 | Device partitions are additional logical block devices present on the | ||
5 | SD/MMC device. | ||
6 | |||
7 | As of this writing, MMC boot partitions as supported and exposed as | ||
8 | /dev/mmcblkXboot0 and /dev/mmcblkXboot1, where X is the index of the | ||
9 | parent /dev/mmcblkX. | ||
10 | |||
11 | MMC Boot Partitions | ||
12 | =================== | ||
13 | |||
14 | Read and write access is provided to the two MMC boot partitions. Due to | ||
15 | the sensitive nature of the boot partition contents, which often store | ||
16 | a bootloader or bootloader configuration tables crucial to booting the | ||
17 | platform, write access is disabled by default to reduce the chance of | ||
18 | accidental bricking. | ||
19 | |||
20 | To enable write access to /dev/mmcblkXbootY, disable the forced read-only | ||
21 | access with: | ||
22 | |||
23 | echo 0 > /sys/block/mmcblkXbootY/force_ro | ||
24 | |||
25 | To re-enable read-only access: | ||
26 | |||
27 | echo 1 > /sys/block/mmcblkXbootY/force_ro | ||