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authorCai Zhiyong <caizhiyong@huawei.com>2013-09-12 01:20:09 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-12 02:56:57 +0400
commitbab55417b10c95e6bff8cea315c315adfa009487 (patch)
tree56bfc578d47c7ea786bf6a35bf946f37e9b458b1 /Documentation/block
parented751e683c563be64322b9bfa0f0f7e5da9bd37c (diff)
downloadlinux-bab55417b10c95e6bff8cea315c315adfa009487.tar.xz
block: support embedded device command line partition
Read block device partition table from command line. The partition used for fixed block device (eMMC) embedded device. It is no MBR, save storage space. Bootloader can be easily accessed by absolute address of data on the block device. Users can easily change the partition. This code reference MTD partition, source "drivers/mtd/cmdlinepart.c" About the partition verbose reference "Documentation/block/cmdline-partition.txt" [akpm@linux-foundation.org: fix printk text] [yongjun_wei@trendmicro.com.cn: fix error return code in parse_parts()] Signed-off-by: Cai Zhiyong <caizhiyong@huawei.com> Cc: Karel Zak <kzak@redhat.com> Cc: "Wanglin (Albert)" <albert.wanglin@huawei.com> Cc: Marius Groeger <mag@sysgo.de> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Brian Norris <computersforpeace@gmail.com> Cc: Artem Bityutskiy <dedekind@infradead.org> Signed-off-by: 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>
Diffstat (limited to 'Documentation/block')
-rw-r--r--Documentation/block/cmdline-partition.txt39
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diff --git a/Documentation/block/cmdline-partition.txt b/Documentation/block/cmdline-partition.txt
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+Embedded device command line partition
+=====================================================================
+
+Read block device partition table from command line.
+The partition used for fixed block device (eMMC) embedded device.
+It is no MBR, save 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)