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linux-next/Documentation/block/cmdline-partition.txt
Paul Gortmaker 080506ad0a block: change config option name for cmdline partition parsing
Recently commit bab55417b1 ("block: support embedded device command
line partition") introduced CONFIG_CMDLINE_PARSER.  However, that name
is too generic and sounds like it enables/disables generic kernel boot
arg processing, when it really is block specific.

Before this option becomes a part of a full/final release, add the BLK_
prefix to it so that it is clear in absence of any other context that it
is block specific.

In addition, fix up the following less critical items:
 - help text was not really at all helpful.
 - index file for Documentation was not updated
 - add the new arg to Documentation/kernel-parameters.txt
 - clarify wording in source comments

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Cai Zhiyong <caizhiyong@huawei.com>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-30 14:31:02 -07:00

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Embedded device command line partition parsing
=====================================================================
Support for reading the block device partition table from the command line.
It is typically used for fixed block (eMMC) embedded devices.
It has no MBR, so saves storage space. Bootloader can be easily accessed
by absolute address of data on the block device.
Users can easily change the partition.
The format for the command line is just like mtdparts:
blkdevparts=<blkdev-def>[;<blkdev-def>]
<blkdev-def> := <blkdev-id>:<partdef>[,<partdef>]
<partdef> := <size>[@<offset>](part-name)
<blkdev-id>
block device disk name, embedded device used fixed block device,
it's disk name also fixed. such as: mmcblk0, mmcblk1, mmcblk0boot0.
<size>
partition size, in bytes, such as: 512, 1m, 1G.
<offset>
partition start address, in bytes.
(part-name)
partition name, kernel send uevent with "PARTNAME". application can create
a link to block device partition with the name "PARTNAME".
user space application can access partition by partition name.
Example:
eMMC disk name is "mmcblk0" and "mmcblk0boot0"
bootargs:
'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)'
dmesg:
mmcblk0: p1(data0) p2(data1) p3()
mmcblk0boot0: p1(boot) p2(kernel)