Deploy the kernel on your target

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 with a different file system depending on the storage media:

Media	File system
microSD	FAT
eMMC	FAT
NAND flash	UBIFS

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, on the ConnectCore 6:

=> 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

For FAT partitions, you can use the updatefile command to update the kernel or the device tree blobs.

To update the files from userspace, mount the linux partition:

For systems using eMMC, mount the /dev/mmcblk0p1 device as a vfat file system:

root@ccimx6sbc:~# mkdir /mnt/linux
root@ccimx6sbc:~# mount -t vfat /dev/mmcblk0p1 /mnt/linux
root@ccimx6sbc:~# 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

On the ConnectCore 6, 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.

For systems using a NAND flash, mount the /dev/ubi0_0 device as a ubifs file system:

root@ccimx6ulstarter:~# mkdir /mnt/linux
root@ccimx6ulstarter:~# mount -t ubifs /dev/ubi0_0 /mnt/linux/
root@ccimx6ulstarter:~# ls /mnt/linux/ -l
-rw-rw-r-- 1 1000 1000 648 Sep 8 2016 boot.scr
-rw-rw-r-- 1 1000 1000 5939232 Sep 8 2016 zImage-ccimx6ulstarter.bin
-rw-r--r-- 1 1000 1000 29496 Sep 8 2016 zImage-imx6ul-ccimx6ulstarter-id129.dtb
-rw-r--r-- 1 1000 1000 29496 Sep 8 2016 zImage-imx6ul-ccimx6ulstarter-wb.dtb
-rw-r--r-- 1 1000 1000 28852 Sep 8 2016 zImage-imx6ul-ccimx6ulstarter.dtb

From your development machine, you can now copy the files to the target via ssh. For example, for the ConnectCore 6UL SBC Express/Pro:

scp zImage root@<cc6ul-ip>:/mnt/linux/zImage-ccimx6ulstarter.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.
dey-image-qt-x11-ccimx6qpsbc.boot.vfat or similar on the ConnectCore 6 Plus.
dey-image-qt-x11-ccimx6ulsbc.boot.ubifs or similar on the ConnectCore 6UL SBC Pro.
core-image-base-ccimx6ulstarter.boot.ubifs or similar on the ConnectCore 6UL SBC Express.

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

=> update linux tftp <filename>