APF6 EMMC

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APF6 eMMC layout

By default, the 4GB eMMC on APF6 board 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 Not used
rpmb mmc dev 0 3 512KBytes Not used
User Data mmc dev 0 0 remaining space Kernel, device tree and rootfs

Boot0 partition layout

. SPL IMG ... ENV1 ... ENV2 ...
  • Linux device: /dev/mmcblk2boot0
Offset (blocks) Offset (bytes) Size (bytes) Comment
0 0 1 KB (0x400) Free
0x02 1 KB (0x400) 68 KB U-Boot SPL (apf6-u-boot.spl)
0x8a 69 KB (0x11400) 512 KB U-Boot IMG (apf6-u-boot.img)
Free
0x800 (2048) 1024 KB (0x100000) 10 KB (0x2800) U-Boot environment
Free
0xc00 (3072) 1536 KB (0x180000) 10 KB (0x2800) Redundant U-Boot environment
Free

User Data partition layout

There are two primary partitions on the "User Data" physical partition:

... Boot Rootfs


Name U-Boot device Linux device Offset (bytes) Offset (blocks) Size Comment
MBR NA NA 0 0 512 bytes (1 block) Master Boot Record. (Don't touch it :-) )
... NA NA 512 1 ~1 MBytes (2047 blocks) Free
Boot mmc 0:1 /dev/mmcblk2p1 1M (0x100000) 2048 (0x800) 48 MBytes (98304 blocks) The kernel and the device tree (inside a dtbs/ directory) are on this partition (ext4 formatted)
Rootfs mmc 0:2 /dev/mmcblk2p2 49M (0x3100000) 100352 (0x18800) Rest of space (< 7632896 blocks) the rootfs is 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/mmcblk2p1        # for Boot
# resize2fs /dev/mmcblk2p2        # 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.

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