If you are still interested in this: Building the rootfs for aarch64 seems to work pretty easy when using a current buildroot. I'm not sure about which kernel version to use though, I didn't find one in the repo where we get the other kernels from.
If you are still interested in this: Building the rootfs for aarch64 seems to work pretty easy when using a current buildroot. I'm not sure about which kernel version to use though, I didn't find one in the repo where we get the other kernels from.