summaryrefslogtreecommitdiff
path: root/Documentation/block/cmdline-partition.rst
diff options
context:
space:
mode:
authorMauro Carvalho Chehab <mchehab+samsung@kernel.org>2019-04-19 01:45:00 +0300
committerMauro Carvalho Chehab <mchehab+samsung@kernel.org>2019-07-15 15:20:27 +0300
commit898bd37a92063e46bc8d7b870781cecd66234f92 (patch)
tree1eac9c597d45080cc2ff366f6e882a87fcea2d2b /Documentation/block/cmdline-partition.rst
parent53b9537509654a6267c3f56b4d2e7409b9089686 (diff)
downloadlinux-898bd37a92063e46bc8d7b870781cecd66234f92.tar.xz
docs: block: convert to ReST
Rename the block documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/block/cmdline-partition.rst')
-rw-r--r--Documentation/block/cmdline-partition.rst53
1 files changed, 53 insertions, 0 deletions
diff --git a/Documentation/block/cmdline-partition.rst b/Documentation/block/cmdline-partition.rst
new file mode 100644
index 000000000000..530bedff548a
--- /dev/null
+++ b/Documentation/block/cmdline-partition.rst
@@ -0,0 +1,53 @@
+==============================================
+Embedded device command line partition parsing
+==============================================
+
+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 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 uses fixed block device.
+ Its disk name is also fixed, such as: mmcblk0, mmcblk1, mmcblk0boot0.
+
+<size>
+ 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>
+ partition start address, in bytes.
+ offset may contain an optional suffix of (upper or lower case):
+
+ K, M, G, T, P, E.
+
+(part-name)
+ partition name. Kernel sends 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 names are "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)