This directory contains the prerequisites for cross-building the kernel snap.
Specifically, it contains the dependencies for the ubuntu-core-initramfs tool
built for RISC-V 64-bit, required to build the uc-initrd snap.
Packages were built on a RISC-V 64-bit machine running Ubuntu Server 20.04.
I assume you are likewise on 20.04. On more recent (or older) versions of Ubuntu, you might not need to do this. For instance, dracut-core 051 is available on Impish, so you don't need to install it here - just do so in the usual way.
systemd-bootchart is not built for RISC-V because upstream has abandoned the
project (seems like). If it had kept up with systemd, we probably wouldn't
have to build it ourselves. But here we are.
The ubuntu-core-initramfs tool is not built for RISC-V, and intentionally so.
We must do it ourselves.
To build your initrd...
Install the following:
dpkg -i systemd-bootchart_233-2_riscv64.deb
dpkg -i dracut-core_051-1_riscv64.deb
dpkg -i ubuntu-core-initramfs_51_riscv64.deb
cd uc-initrd/
snapcraft --destructive-mode --target-arch=riscv64 --enable-experimental-target-arch
The initrd snap is required to use the snapcraft plugins to cross-compile the
kernel snap. For instructions, see the kernel snap readme.
It will probably be the case at some future time that I am not actively updating these packages. In such a case, you can follow these more generic instructions to get newer version of these packages (with small tweaks as necessary, left as an exercise for the builder).
Would recommend doing all of this work on the board :)
# Uncomment the deb-src lines in /etc/apt/sources.list and run apt-get update.
apt-get build-dep systemd-bootchart # Needed for initrd, not built for riscv64
apt-get source systemd-bootchart # Requires a patch! Diverged from upstream.
cd systemd-bootchart*/
patch -p1 < ../patches/riscv64.patch
dpkg-buildpackage -us -uc -nc
cd ../
dpkg -i systemd-bootchart_233-2_riscv64.deb
# You might require a more recent version of Dracut!
wget http://ports.ubuntu.com/pool/universe/d/dracut/dracut-core_051-1_riscv64.deb
dpkg -i dracut-core_051-1_riscv64.deb
git clone https://git.launchpad.net/ubuntu-core-initramfs
cd ubuntu-core-initramfs
git checkout core20 # Presumably
patch -p1 < ../patches/ubuntu-core-initramfs.patch
apt-get build-dep .
dpkg-buildpackage -us -uc -nc
cd ../
dpkg -i ubuntu-core-initramfs_51_riscv64.deb
cd uc-initrd/
snapcraft --destructive-mode --target-arch=riscv64 --enable-experimental-target-arch