EMMC OPOS8MM

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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

... SPL ... IMG ...
  • 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

  • Not used !

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
  • In menu:
|     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

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