0001 ==============================================
0002 Embedded device command line partition parsing
0003 ==============================================
0004
0005 The "blkdevparts" command line option adds support for reading the
0006 block device partition table from the kernel command line.
0007
0008 It is typically used for fixed block (eMMC) embedded devices.
0009 It has no MBR, so saves storage space. Bootloader can be easily accessed
0010 by absolute address of data on the block device.
0011 Users can easily change the partition.
0012
0013 The format for the command line is just like mtdparts:
0014
0015 blkdevparts=<blkdev-def>[;<blkdev-def>]
0016 <blkdev-def> := <blkdev-id>:<partdef>[,<partdef>]
0017 <partdef> := <size>[@<offset>](part-name)
0018
0019 <blkdev-id>
0020 block device disk name. Embedded device uses fixed block device.
0021 Its disk name is also fixed, such as: mmcblk0, mmcblk1, mmcblk0boot0.
0022
0023 <size>
0024 partition size, in bytes, such as: 512, 1m, 1G.
0025 size may contain an optional suffix of (upper or lower case):
0026
0027 K, M, G, T, P, E.
0028
0029 "-" is used to denote all remaining space.
0030
0031 <offset>
0032 partition start address, in bytes.
0033 offset may contain an optional suffix of (upper or lower case):
0034
0035 K, M, G, T, P, E.
0036
0037 (part-name)
0038 partition name. Kernel sends uevent with "PARTNAME". Application can
0039 create a link to block device partition with the name "PARTNAME".
0040 User space application can access partition by partition name.
0041
0042 Example:
0043
0044 eMMC disk names are "mmcblk0" and "mmcblk0boot0".
0045
0046 bootargs::
0047
0048 'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)'
0049
0050 dmesg::
0051
0052 mmcblk0: p1(data0) p2(data1) p3()
0053 mmcblk0boot0: p1(boot) p2(kernel)
