| Gentoo ARCH | defconfig | boards to test | notes |
| ARM | multi_v7_defconfig | qemu(virt-2.11) | |
| ARM64 | arm64_defconfig | qemu(virt) | |
| alpha | defconfig | qemu(clipper) | defconfig miss CONFIGs |
| hppa/parisc | generic-32bit_defconfig | qemu(hppa) | LAVA need a patch https://git.lavasoftware.org/lava/lava/-/merge_requests/1419 Merged, will be in 2021.[2-x] |
| m68k | mac_defconfig | qemu(q800) | LAVA need a patch https://git.lavasoftware.org/lava/lava/-/merge_requests/1424 Merged, will be in 2021.[2-x] |
| MIPS32 | malta_kvm_guest_defconfig | qemu(malta) | |
| PPC | pmac32_defconfig | qemu(g3beige) | Need CONFIGs |
| PPC64 | pseries_defconfig | qemu(pseries) | |
| riscv | defconfig | qemu(virt) | Need qemu > x (at least buster is too old) |
| sparc64 | sparc64_defconfig | qemu(sun4u) | defconfig miss CONFIGs |
| x86 | i386_defconfig | qemu(pc) | |
| x86_64 | x86_64_defconfig | qemu(pc) |
Note: ia64 is not boot-testable due to lack of qemu hardware
- Each arch could be compiled by more than one toolchain
- Each arch could have more than 1 defconfig
- Each board could be booted by more than 1 defconfig
- earch defconfig could boot more than 1 board
- Filtering board by arch is not a correct way (example lot of ppc boards work with only a subset of ppc defconfigs.)
- So the only viable way to find board to boot is to filter per defconfig or better per CONFIG_ (permiting to use randconfig)
Example: qemu-cubieboard could be booted by
- arm/multi_v7_defconfig/gcc
- arm/multi_v7_defconfig/clang
- arm/sunxi_defconfig/gcc
- arm/sunxi_defconfig/clang
- Each arch should have a list of defconfig to build
- Each defconfig could have a list of CONFIG fixups
- Each arch should have a list of toolchains to use (gcc vs clang for example)
- each build could be identified by its directory source/arch/defconfig/toolchain
- each board should have a list of CONFIG necessary to boot them (mostly CONFIG_ARCH_XXXX)
- For each build, compare the final .config and generate jobs for each matching board.
- A list for lava labs must exists with an user/token.
- the user must not be staff/admin of the lab
- For each lab check device-types availlable and the state of related board (must be Good)
TODO: Different rootfs could be booted
- "classic" multilib
- hardened (SELinux)
- openRC vs systemd
- Gentoo specifics
- general tests
- kselftest
Goal: Compiling kernel using official stage3.
For x86_64, it is easy since no cross-compilation is needed. But for other arches, we cannot use stage3 as-is. Using a worker of the same arch for each arch is not a good solution since lot of arches will be either too slow or hard to find.
So the solution is to use qemu-user-static. On x86_64, using qemu-user-static imply no performance loss, so we can handle all arches the same way.
With qemu-user-static we can chroot in a stage3, and compile kernel using the toolchain present in it. We just need to "mount" sources and output directory in this stage3.
The original stage3 needs some modification:
- It need a buildbot user with the same id than the worker.
- It need bc and libelf
Emerging bc/libelf via qemu-user is long, so we use a binary package cache in a volume. But even with binpkg, it took too many time, so the final stage3 must be cached, so that we have to do nothing when we need it.