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Documentation: block: cmdline-partition.txt fixes and additions 

Make the description of the kernel command line option "blkdevparts"
a bit more flowing and readable.

Fix a few typos.
Add the optional <size> and <offset> suffixes.
Note that size can be "-" to indicate all of the remaining space.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Cai Zhiyong <caizhiyong@huawei.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Randy Dunlap 2018-05-06 11:50:29 -07:00 committed by Jonathan Corbet
parent f318a44e15
commit f6dbf65b65
1 changed files with 14 additions and 7 deletions
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21
Documentation/block/cmdline-partition.txt
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@ -1,7 +1,9 @@
Embedded device command line partition parsing Embedded device command line partition parsing
===================================================================== =====================================================================
Support for reading the block device partition table from the command line. The "blkdevparts" command line option adds support for reading the
block device partition table from the kernel command line.
It is typically used for fixed block (eMMC) embedded devices. It is typically used for fixed block (eMMC) embedded devices.
It has no MBR, so saves storage space. Bootloader can be easily accessed It has no MBR, so saves storage space. Bootloader can be easily accessed
by absolute address of data on the block device. by absolute address of data on the block device.
@ -14,22 +16,27 @@ blkdevparts=<blkdev-def>[;<blkdev-def>]
<partdef> := <size>[@<offset>](part-name) <partdef> := <size>[@<offset>](part-name)
<blkdev-id> <blkdev-id>
block device disk name, embedded device used fixed block device, block device disk name. Embedded device uses fixed block device.
it's disk name also fixed. such as: mmcblk0, mmcblk1, mmcblk0boot0. Its disk name is also fixed, such as: mmcblk0, mmcblk1, mmcblk0boot0.
<size> <size>
partition size, in bytes, such as: 512, 1m, 1G. partition size, in bytes, such as: 512, 1m, 1G.
size may contain an optional suffix of (upper or lower case):
K, M, G, T, P, E.
"-" is used to denote all remaining space.
<offset> <offset>
partition start address, in bytes. partition start address, in bytes.
offset may contain an optional suffix of (upper or lower case):
K, M, G, T, P, E.
(part-name) (part-name)
partition name, kernel send uevent with "PARTNAME". application can create partition name. Kernel sends uevent with "PARTNAME". Application can
a link to block device partition with the name "PARTNAME". create a link to block device partition with the name "PARTNAME".
user space application can access partition by partition name. User space application can access partition by partition name.
Example: Example:
eMMC disk name is "mmcblk0" and "mmcblk0boot0" eMMC disk names are "mmcblk0" and "mmcblk0boot0".
bootargs: bootargs:
'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)' 'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)'