Updating Little Kernel and Linux kernel from rootfs

Products Support DragonBoard 820c
#1

Hello,

Is there any mechanism to update the Little Kernel or the Linux Kernel/DT from the DB820 Linux userspace?

Thanks,
David

#2

I haven’t tried this on the 820c yet, but I just used dd on the 410c. I suspect the file names and partition numbers will be different, but it might work: Extracting eMMC content of Dragonboard 410c - #3 by ljking

#3

I haven’t tried this on the 820c yet, but I just used dd on the 410c. I suspect the file names and partition numbers will be different, but it might work: https://discuss.96boards.org/t/extracting-emmc-content-of-dragonboard-410c/1038/3?u=ljking

#4

Yes that should work. Little kernel must be written to aboot partition, you can use the partlabel symlink:
dev/disk/by-partlabel/aboot
The kernel and DT are part of the boot image (boot.img) that you can write as well with dd (or cat) into, e.g: cat boot.img > /dev/disk/by-partlabel/boot; sync

For more fine grained changes, like only changing the kernel or DTB, you ca use the dbootimg tool which is part of https://github.com/96boards/dt-update

# install tool to extract blob from boot partition
git clone https://github.com/96boards/dt-update.git
cd dt-update && make
sudo make install

# Example, update boot partition with the update devicetree blob
dbootimg /dev/disk/by-partlabel/boot -u dtb 820c.dtb
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