How to deploy files to /boot partition with Yocto

Question

I'm trying to deploy some binary files to /boot in a Yocto image for RPi CM3 but it deploys them to the wrong location.

do_install() {
    install -d ${D}/boot/overlays
    install -m 0664 ${WORKDIR}/*.dtb ${D}/boot/overlays/
    install -m 0664 ${WORKDIR}/*.dtbo ${D}/boot/overlays/
}

The files are deployed to /boot in the / partition of the final image, but not to the /boot partition. So they are not available at boot time.

I already googled and studied the kernel recipes (and classes) of the Poky distribution but I didn't find the mechanism it uses how to ensure that the files are deployed to the boot image (and not to the /boot dir in the root image).

Any help is appreciated :)

Update #1

In my local.conf I did:

IMAGE_BOOT_FILES_append = " \
  overlays/3dlab-nano-player.dtbo \
  overlays/adau1977-adc.dtbo \
  ...
"

And in my rpi3-overlays.bb

do_deploy() {
    install -d ${DEPLOYDIR}/${PN}
    install -m 0664 ${WORKDIR}/*.dtb ${DEPLOYDIR}/${PN}
    install -m 0664 ${WORKDIR}/*.dtbo ${DEPLOYDIR}/${PN}

    touch ${DEPLOYDIR}/${PN}/${PN}-${PV}.stamp
}

Using this the image builds, but the files stillt don't get deployed in the /boot partition. Using RPI_KERNEL_DEVICETREE_OVERLAYS I get a build error because the kernel recipe tries to build the dtbo files like dts files.

Primarily

Answer 1

I've battled the problem of deploying files to the /boot partition over last few days and came up with a solution. Below instructions are for Yocto Kirkstone 4.0.1.

1. In case of working with linux-raspberrypi add it as a dependency to your recipe, same with dtc-native for the compilation of Device Tree files.

   DEPENDS:append = " linux-raspberrypi"
   DEPENDS:append = " dtc-native"
   

2. Prepare the you recipe so that it deploys the file to ${DEPLOYDIR} - directory where files of the final image are stored. Inherit from the deploy class, it's important to add the deploy task with addtask. Below do_deploy function assumes that all the files are compiled and ready for deployment.

   inherit deploy
   
   do_deploy() {
       install -m 0664 ${S}/adau1977-adc.dtbo ${DEPLOYDIR}/adau1977-adc.dtbo
   }
   
   addtask deploy after do_compile
   

3. To burn the file into the specified directory on the /boot partition, use below syntax of the IMAGE_BOOT_FILES variable:

   IMAGE_BOOT_PARTITION:append = " file_name_in_deploydir;path/on/boot/filename.extension"
   

   For example

   IMAGE_BOOT_PARTITION:append = " adau1977-adc.dtbo;overlays/adau1977-adc.dtbo"
   

   Put this line into your local.conf

This should work!

Markhor

Answer 2

RPI images are created with sdimage-raspberrypi.wks WIC wks file. It contains:

part /boot --source bootimg-partition ...

so it uses bootimg-partition.py wic plugin to generate /boot partition. It copies every files defined by IMAGE_BOOT_FILES variable.

It seems you want to add some devicetree overlays, so you need to modify machine configuration and more specifically RPI_KERNEL_DEVICETREE_OVERLAYS variable. IMAGE_BOOT_FILES variable is set in rpi-base.inc.

If you don't have any custom machine or custom distro defined, you can add it in local.conf:

RPI_KERNEL_DEVICETREE_OVERLAYS_append = " <deploy-path>/<dto-path>"

You can see here how to add files in deploy directory.

Hedge

Thank you for your answer! Unfortunately I did some mistake or have to go a different approach. When using RPI_KERNEL_DEVICETREE_OVERLAYS it tries to compile the dtbo's like they would be dts files. Using IMAGE_BOOT_FILES the image builds but without the files. I'l update my question with more details. – Primarily

Maybe try to change install by cp ? If you use bitbake -v rpi3-overlays, do you see files to be copied ? – Hedge

Another way could be to patch kernel with new dts file to get it compiled by Yocto? – Hedge

I have no local build (only on build server), but I can try that. But I don't think cp will do anything different than install. The files are deployed, but in the /boot directory on the root fs instead of the /boot fs. In theory I could convert the dtbos back to dts, but as I get them in binary form it would be an additional step and this would only apply to dtbos. When I have to deploy other file types then that solution wouldn't work. – Primarily

Which Yocto version do you use? – Hedge

can you try to add your recipe in do_image_wic[depends] of rpi-base.inc – Hedge

I'm using the warrior branch. To add the recipe it's do_image_wic[depends]_append = " rpi3-overlays:do_deploy" right? – Primarily

not sure, try do_image_wic[depends] += "rpi3-overlays:do_deploy" – Hedge

I added that line to my recipe, but the result didn't change :( – Primarily

In which recipe did you add that line? Try to add it directly to rpi-base.inc file just to be sure? I think IMAGE_BOOT_FILES_append should contain rpi3-overlays/3dlab-nano-player.dtbo instead of overlays/3dlab-nano-player.dtbo. Can you use bitbake -v -D <your_image> to verify your files are taken into account during wic process? – Hedge

Thank you very much for your help! Will try that, but that will take until tomorrow as I'll have to make a manual build in order to do the change and run bitbake with different options. – Primarily

Answer 3

After too many hours of investigation it turned out, that deploying files to other partitions than / is not easily possible. I now went the way of a post-processing script that mounts the final image, deploys the additional files and unmounts it.

# Ensure the first loopback device is free to use
sudo -n losetup -d /dev/loop0 || true

# Create a loopback device for the given image
sudo -n losetup -Pf ../deploy/images/bapi/ba.rootfs.rpi-sdimg

# Mount the loopback device
mkdir -p tmp
sudo -n mount /dev/loop0p1 tmp

# Deploy files
sudo -n cp -n ../../meta-ba-rpi-cm3/recipes-core/rpi3-overlays/files/* tmp/overlays/
sudo -n cp ../../conf/config.txt tmp/config.txt
sudo -n cp ../../conf/cmdline.txt tmp/cmdline.txt

# Unmount the image and free the loopback device
sudo -n umount tmp
sudo -n losetup -d /dev/loop0

Primarily