If any file in the `overlay` directory changes, the `build-rootfs.sh`
script needs to be re-run in order to copy the changes into the
destination root and regenerate the SquashFS image.
Instead of copying the Portage configuration files to `/etc/portage` and
`/usr/${target}/etc/portage`, the build scripts now use the
configuration directories from the source directory. This avoids issues
with changes (especially removal of files) getting propagated to the
actual configuration paths.
The Portage packages that need to be built and/or installed are now
specified in the `build.packages` and `install.packages` files,
respectively. Similarly, packages to be installed on the host system
are specified in `host-tools.packages`. Finally, the
`installonly.packages` file contains a list of packages that are
installed in the destination root, but not built in the sysroot
beforehand.
This allows `make` to better track when the package sets change. It
will also make it easier to maintain different sets for different
variants in the future.
When running inside a QEMU microvm with the source directory shared
via 9pfs, the kernel build process fails
> Error: Could not mmap file: vmlinux
Thus, we need to run the build in a path on a local filesystem. To
support this, the Makefile now supports an `O` option, and all the build
scripts have been adjusted to make use of it as needed.
Since building in a local filesystem would ultimately discard the final
artifacts when the VM terminates, we need yet a different location for
the files we want to keep. The `IMAGESDIR` option can be used to
specify this path. This path can be on a shared filesystem, thus
saving the artifacts outside the microvm.
Building the OS is now as simple as running `make` on a Gentoo system.
Interestingly, when `make` is executed as a (grand)child process of
another `make` process, it always prints an `Entering directory ...`
message. This breaks the `make kernelversion` command, by adding
extraneous text to the output.
Dustin