OPOS8MM eMMC layout
By default, the 4GB eMMC on OPOS8MM module has 4 physical/hardware partitions:
| Boot0
|
Boot1
|
RPMB
|
User Data
|
| Name |
U-Boot name |
Size |
Comment
|
| boot0 |
mmc dev 0 1 |
2MBytes |
U-Boot is installed on this partition
|
| boot1 |
mmc dev 0 2 |
2MBytes |
U-Boot env is installed on this partition
|
| rpmb |
mmc dev 0 3 |
512KBytes |
Not used
|
| User Data |
mmc dev 0 0 |
remaining space (~3,7GBytes) |
Kernel, device tree and rootfs
|
Boot0 partition layout
- Linux device: /dev/mmcblk0boot0
| Offset (blocks) |
Offset (bytes) |
Size (bytes) |
Comment
|
|
|
|
Free
|
| 0x42 |
33 KiB (0x8400) |
215 KiB |
U-Boot SPL (opos8mm-u-boot.spl)
|
|
|
|
Free
|
| 0x300 |
384 KiB (0x6000) |
~700 KiB |
U-Boot IMG (opos8mm-u-boot.itb)
|
|
|
|
Free
|
Boot1 partition layout
| U-Boot env
|
...
|
U-Boot redundant env
|
...
|
- Linux device: /dev/mmcblk0boot1
| Offset (blocks) |
Offset (bytes) |
Size (bytes) |
Comment
|
| 0 |
0 |
16 KiB |
U-Boot environment
|
|
|
|
Free
|
|
|
16 KiB |
U-Boot redundant environment
|
|
|
|
Free
|
RPMB partition layout
User Data partition layout
There are 3 partitions on the "User Data" physical partition:
| ...
|
Failsafe/Update (primary)
|
Default Rootfs (primary)
|
Home/Data (primary)
|
| Name |
U-Boot device |
Linux device |
Offset (bytes) |
Offset (sectors/blocs) |
Size |
Comment
|
| MBR |
NA |
NA |
0 |
0 |
512 bytes (1 block) |
Master Boot Record + some spare space ( -> Don't touch it :-) )
|
| Failsafe |
mmc 0:1 |
/dev/mmcblk0p1 |
1M |
2048 (0x800) |
512 MBytes (1048576 sectors) |
system/rootfs to restore your board in case of problem or setup a safe update mechanism (ext4 formatted)
|
| Rootfs |
mmc 0:2 |
/dev/mmcblk0p2 |
|
1050624 (0x10800) |
512 MBytes (1048576 sectors) |
the default booted rootfs is on this partition (ext4 formatted)
|
| Home/Data |
mmc 0:3 |
/dev/mmcblk0p3 |
|
2099200 (0x200800) |
Rest of space: ~2,7 GBytes (5634048 sectors) |
HOME can be stored on this partition (ext4 formatted)
|
- By default, when flashed from U-Boot, rootfs and boot are only occupying the size of the .ext4 images used during flashing. If you want to increase the rootfs/boot size to all available free space then, after Linux has booted, use the following commands:
# resize2fs /dev/mmcblk0p2 # for Rootfs
- Or with apf-config command:
# apf-config
| 1 Expand Filesystem(s) OS can then use all eMMC/SD space |
Rootfs/Boot will then be extended to all the "Rootfs"/"Boot" eMMC partitions space.
Tips
- Commands to partition User Data from fdisk on Host PC with U-Boot UMS. Check /dev/sdc is your OPOS8MM device otherwise you may destroy your PC partition table !!!:
$ sudo echo -e 'size=512MiB,type=0x83\nsize=512MiB,type=0x83\ntype=0x83' | sfdisk /dev/sdc
$ sudo mkfs.ext4 -O ^64bit,^metadata_csum,uninit_bg /dev/sdc1
$ sudo mkfs.ext4 -O ^64bit,^metadata_csum,uninit_bg /dev/sdc2
$ sudo mkfs.ext4 -O ^64bit,^metadata_csum,uninit_bg /dev/sdc3
Links
