SD card format documentation

#1

Hi, I’m trying to build an embedded OS image for ROCK Pi 4 with Yocto/OpenEmbedded. I understand there is no official support for this, so I’m on my own.

Right now I have the image building with my custom layer on top of meta-rockchip, that is using radxa/kernel and radxa/u-boot instead of the official ROCKCHIP-Linux BSP forks. So everything seems fine, except there is no HDMI output when I boot from the SD card, and there is no network connectivity. I’m able to boot the official Ubuntu Server image just fine, so I know there is nothing wrong with my ROCK Pi. I think there is something wrong with the way I’m building the SD card image.

I am waiting to get my USB-Serial device in the mail so I can debug via the UART serial console, but in the meantime… is there any documentation I can read about the way the SD card should be formatted, and what the ROCK Pi expects to see on the SD card so it can boot?

#2

Just putting this here for anyone who’s searching for the same thing: I found documentation about the bootable format on the Rockchip wiki:

http://opensource.rock-chips.com/wiki_Boot_option

If anyone has any additional resources about this topic, please share them.

#3

Buildroot is the official “commercial” distro supported by Rockchp.

http://opensource.rock-chips.com/wiki_Yocto

#4

I agree that’s what it says on their documentation, however I evaluated Buildroot and unfortunately it won’t work for my purposes - I need a package repository.

Rockchip maintains a Yocto configuration layer that gets actively updated: https://github.com/rockchip-linux/meta-rockchip

Right now I’m pretty sure that the image is getting generated correctly. However, the boot.img that Yocto gives me isn’t readable by mount.vfat or mount.ext2 (or even mount -t auto), so I think something is going wrong there.

#5

@wbn

yocto uses different image layout, not exactly as rockchip-bsp we use to generate debian. You can check out/tmp/deploy/images and ls everything, use file to check the image format. It maybe the android boot.img format.

#6

It turns out this is the case. The boot.img generated by the linux-rockchip recipe is in the Android format. I generated an ext2 fs using the instructions here and supplanted boot.img with that, and now it boots.