[yocto] [rauc] create a rescue image

[Patrick Boettcher]

Hi,

On Mon, 25 Mar 2019 16:01:37 +0100
jairo <jairo at futurasmus-knxlab.es> wrote:

> Hi all,
> 
> I want to make a system with a rescue partition.
> 
> What is the minimum to make a rescue image? Or how can it be done?
> 
> I use a board with a imx6 micro from phytec, and in the meta-yogurt
> layer there is a recipe called phytec-initramfs-image.bb that creates
> an image or partition with cpio.gz format of 11MB containing rootfs,
> can it be used That image as a rescue? If so, how do you copy a cpio
> partition in an UBI MTD system?

To create an initramfs rescue image (assuming that's what you would
want to do?) You need to tell yocto that there is a initramfs to be
built:

To your local.conf you can add

  # for initramfs-usage
  INITRAMFS_IMAGE = "rescue-image-initramfs"
  INITRAMFS_IMAGE_BUNDLE = "1"

and you'll to craete a corresponding .bb-file. There are example over
the internet if you search for it. I needed the following packages:

  PACKAGE_INSTALL = "packagegroup-core-boot \
                     ppp          \
                     bash         \
                     sshd         \
                     rauc         \
                     mtd-utils    \
  "

This gave me a initramfs of 25-30 MB and barebox wasnot able to
jump to the kernel so I had to patch.

After that you just need to add a partition for the initramfs and its
device-tree-blob (dtb) to the UBIFS and flash it and boot it.

You should, if you haven't already, come up with a complete strategy of
how to do your updates and upgrades using RAUC or another update-system.

best regards,
--
Patrick.