Enable powerpc in make tinderbox using clang.

[jhb]

Summary

powerpcspe is disabled for now until it has been fixed.

This also adjusts the dependencies for kernels so that we
do not build kernels which for a TARGET_ARCH unless that
TARGET_ARCH is enabled in TARGET_ARCHES_${TARGET}. In
particular, this avoids building powerpcspe kernels for
now, but can also be useful to only build, e.g. mips64
via 'make TARGETS=mips TARGET_ARCHES_mips=mips64'.

Test Plan

• make tinderbox builds powerpc using clang while skipping powerpcspe worlds and kernels

[jhb]

I would probably commit the universe_kernconfs change first and then powerpc second.

[imp]

Makefile

723 ↗

(On Diff #66339)

Is the nesting right on the target arch part of this? It looks weird and makes no sense to me

[jhb]

Makefile

723 ↗

(On Diff #66339)

It works. :)

You end up with the following dependency chain for powerpc (for example):

universe_kernconfs -> universe_kernconfs_{powerpc,powerpc64}

Then:

universe_kernconfs_powerpc -> universe_kernconfs_powerpc_{GENERIC,LINT}
universe_kernconfs_powerpc64 -> universe_kernconfs_powerpc64_{GENERIC64,LINT64}
universe_kernconfs_powerpcspe -> universe_kernconfs_powerpcspe_MPC58XXSPE

As a result, no powerpcspe kernels are built since universe_kernconfs only depends on powerpc and powerpc64 kernels. Once powerpcspe works with clang, we will add it to TARGET_ARCHES_powerpc which will then enable universe_kernconfs_powerpcspe.

Today what happens is that all of the powerpc kernels regardless of TARGET_ARCH are dependencies of universe_kernconfs_powerpc.

For a non-powerpc example, try the following command:

make TARGETS=mips TARGET_ARCHES_mips=mips64 MAKE_JUST_KERNELS=yes -n tinderbox NO_CLEAN=yes

Stock head will build all mips kernels including o32 and n32 kernels. With this patch it only builds n64 kernels. Worlds already DTRT. If you do MAKE_JUST_WORLDS it will only build the mips64 world.

Part of the weirdness is that universe_kernconfs is built in a nested make invocation where there is only one TARGET active, so using universe_kernconfs_${TARGET}_${TARGET_ARCH} would be redundant. Of course, this means that universe_kernconf_${TARGET}_${kernel} is also kind of redundant and could instead just be universe_kernconf_${kernel} and it would DTRT.

One side effect of this change btw is that kernel builds are now sorted first by target_arch then alphabetically, so now all the armv6 kernels build first rather than v6 and v7 kernels interleaved in alphabetical order.

[imp]

Ok. Things make sense now....