The linux partition contains the following elements:

  • The kernel binary.

  • Device tree blobs and overlays.

  • A U-Boot bootscript to boot the system.

    The main purpose of the bootscript is to select the appropriate device tree blob and overlays depending on the detected SOM variant and carrier board. This element is provided by the bootloader Digi Embedded Yocto recipe, not the kernel.

The linux partition is formatted in FAT file system.

Update files from U-Boot

To list the contents of the linux partition on MMC media, run ls mmc x:y in the U-Boot console where x is the device index (starting at 0) and y is the partition index (starting at 1). For example:

=> ls mmc 0:1
  9901307   Image.gz-ccimx8mm-dvk.bin
    67455   ccimx8mm-dvk.dtb
      858   _ov_board_lvds_ccimx8m-dvk.dtbo
      731   _ov_board_user-leds_ccimx8m-dvk.dtbo
      710   _ov_som_bt_ccimx8m.dtbo
      656   _ov_som_mca-keypad_ccimx8m.dtbo
      605   _ov_som_wifi_ccimx8m.dtbo
     1857   boot.scr

8 file(s), 0 dir(s)

To update the files from U-Boot console, run updatefile command. See Update files within partition.

Update files from Linux

The linux partition is automatically mounted to /mnt/linux, but as a read-only filesystem.

To list the contents of the linux partition:

-rwxr-xr-x    1 root     root       9901319 Feb 21 20:20 Image.gz-{pfm-codename-pro}.bin
-rwxr-xr-x    1 root     root           858 Feb 21 20:20 _ov_board_lvds_ccimx8m-dvk.dtbo
-rwxr-xr-x    1 root     root           731 Feb 21 20:20 _ov_board_user-leds_ccimx8m-dvk.dtbo
-rwxr-xr-x    1 root     root           710 Feb 21 20:20 _ov_som_bt_ccimx8m.dtbo
-rwxr-xr-x    1 root     root           656 Feb 21 20:20 _ov_som_mca-keypad_ccimx8m.dtbo
-rwxr-xr-x    1 root     root           605 Feb 21 20:20 _ov_som_wifi_ccimx8m.dtbo
-rwxr-xr-x    1 root     root          1857 Feb 21 20:20 boot.scr
-rwxr-xr-x    1 root     root         67455 Feb 21 20:20 {pfm-codename-pro}.dtb

To update the files from user space, remount the linux partition with read/write permissions:

~$ mount -o remount,rw /dev/mmcblk0p1 /mnt/linux

From your development machine, you can now copy the files to the target via ssh. For example:

~$ scp Image.gz root@<cc8mmini-ip>:/mnt/linux/Image.gz-ccimx8mm-dvk.bin

When building from Digi Embedded Yocto, all the elements are packaged together in a single file:

  • dey-image-qt-xwayland-ccimx8mm-dvk.boot.vfat or similar on the ConnectCore 8M Mini Development Kit.

To update the entire linux partition from U-Boot console, save the image file to your TFTP server and use the update command in U-Boot:

=> update linux tftp <filename>