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53 lines
1.6 KiB
53 lines
1.6 KiB
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Embedded device command line partition parsing |
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The "blkdevparts" command line option adds support for reading the |
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block device partition table from the kernel command line. |
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It is typically used for fixed block (eMMC) embedded devices. |
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It has no MBR, so saves storage space. Bootloader can be easily accessed |
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by absolute address of data on the block device. |
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Users can easily change the partition. |
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The format for the command line is just like mtdparts: |
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blkdevparts=<blkdev-def>[;<blkdev-def>] |
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<blkdev-def> := <blkdev-id>:<partdef>[,<partdef>] |
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<partdef> := <size>[@<offset>](part-name) |
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<blkdev-id> |
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block device disk name. Embedded device uses fixed block device. |
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Its disk name is also fixed, such as: mmcblk0, mmcblk1, mmcblk0boot0. |
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<size> |
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partition size, in bytes, such as: 512, 1m, 1G. |
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size may contain an optional suffix of (upper or lower case): |
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K, M, G, T, P, E. |
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"-" is used to denote all remaining space. |
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<offset> |
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partition start address, in bytes. |
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offset may contain an optional suffix of (upper or lower case): |
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K, M, G, T, P, E. |
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(part-name) |
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partition name. Kernel sends uevent with "PARTNAME". Application can |
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create a link to block device partition with the name "PARTNAME". |
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User space application can access partition by partition name. |
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Example: |
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eMMC disk names are "mmcblk0" and "mmcblk0boot0". |
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bootargs:: |
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'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot),-(kernel)' |
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dmesg:: |
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mmcblk0: p1(data0) p2(data1) p3() |
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mmcblk0boot0: p1(boot) p2(kernel)
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