The linux partition contains the following elements:

  • The kernel binary.

  • Several device tree blobs for each SOM and carrier board variant.

  • A U-Boot bootscript to boot the system.

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

The linux partition is formatted depending on the storage media:

Media File system

microSD

FAT

eMMC

FAT

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
  5721120   zimage-ccimx6sbc.bin
    49226   zimage-imx6dl-ccimx6sbc.dtb
    49405   zimage-imx6dl-ccimx6sbc-w.dtb
    49492   zimage-imx6dl-ccimx6sbc-wb.dtb
    51877   zimage-imx6q-ccimx6sbc.dtb
    52052   zimage-imx6q-ccimx6sbc-w.dtb
    52139   zimage-imx6q-ccimx6sbc-wb.dtb
    52335   zimage-imx6q-ccimx6sbc-wb-ldo-bypass.dtb
    52073   zimage-imx6q-ccimx6sbc-id129.dtb
    52147   zimage-imx6q-ccimx6sbc-id130.dtb
    49474   zimage-imx6dl-ccimx6sbc-id131.dtb
     2336   boot.scr

12 file(s), 0 dir(s

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

To update the files from user space, mount the linux partition. For that, you need to mount the /dev/mmcblk0p1 device as a vfat file system.

~# mkdir /mnt/linux
~# mount -t vfat /dev/mmcblk0p1 /mnt/linux
~# ls -l /mnt/linux
-rwxr-xr-x    1 root     root          2336 Feb  9 12:47 boot.scr
-rwxr-xr-x    1 root     root       5722520 Feb  9 12:47 zImage-ccimx6sbc.bin
-rwxr-xr-x    1 root     root         49474 Feb  9 12:47 zImage-imx6dl-ccimx6sbc-id131.dtb
-rwxr-xr-x    1 root     root         49405 Feb  9 12:47 zImage-imx6dl-ccimx6sbc-w.dtb
-rwxr-xr-x    1 root     root         49492 Feb  9 12:47 zImage-imx6dl-ccimx6sbc-wb.dtb
-rwxr-xr-x    1 root     root         49226 Feb  9 12:47 zImage-imx6dl-ccimx6sbc.dtb
-rwxr-xr-x    1 root     root         52139 Feb  9 12:47 zImage-imx6q-ccimx6sbc-id129.dtb
-rwxr-xr-x    1 root     root         52147 Feb  9 12:47 zImage-imx6q-ccimx6sbc-id130.dtb
-rwxr-xr-x    1 root     root         52052 Feb  9 12:47 zImage-imx6q-ccimx6sbc-w.dtb
-rwxr-xr-x    1 root     root         52335 Feb  9 12:47 zImage-imx6q-ccimx6sbc-wb-ldo-bypass.dtb
-rwxr-xr-x    1 root     root         52139 Feb  9 12:47 zImage-imx6q-ccimx6sbc-wb.dtb
-rwxr-xr-x    1 root     root         51877 Feb  9 12:47 zImage-imx6q-ccimx6sbc.dtb

The linux partition is automatically mounted to /mnt/linux, but as a read-only filesystem. To be able to write on the partition, remount it read/write with 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 zImage root@<cc6-ip>:/mnt/linux/zImage-ccimx6sbc.bin

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

  • dey-image-qt-x11-ccimx6sbc.boot.vfat or similar on the ConnectCore 6 SBC.

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>