40 lines
1.3 KiB
Plaintext
40 lines
1.3 KiB
Plaintext
|
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)
|