PPC64 supports two ABIs: ELF v1 and v2.
ELFv1 is historically what GCC and most packages expect, but this is
changing because musl outright does not work with ELFv1. So any distro
which uses musl must use ELFv2. Many other platforms are moving to ELFv2
too, such as FreeBSD (as of v13) and Gentoo (as of late 2020).
Since we use musl extensively, let's default to ELFv2.
Nix gives us the power to specify this declaratively for the entire
system, so ELFv1 is not dropped entirely. It can be specified explicitly
in the target config, e.g. "powerpc64-unknown-linux-elfv1". Otherwise the
default is "powerpc64-unknown-linux-elfv2". For musl,
"powerpc64-unknown-linux-musl" must use elfv2 internally to function.
Looks like these got left behind in the
kernelArch -> linuxArch migration.
Fixes:
* pkgsCross.powernv.linuxHeaders
* pkgsCross.riscv64.linuxHeaders
* pkgsCross.riscv32.linuxHeaders
and dependees
The `platform` field is pointless nesting: it's just stuff that happens
to be defined together, and that should be an implementation detail.
This instead makes `linux-kernel` and `gcc` top level fields in platform
configs. They join `rustc` there [all are optional], which was put there
and not in `platform` in anticipation of a change like this.
`linux-kernel.arch` in particular also becomes `linuxArch`, to match the
other `*Arch`es.
The next step after is this to combine the *specific* machines from
`lib.systems.platforms` with `lib.systems.examples`, keeping just the
"multiplatform" ones for defaulting.
Since 40e7be1 all ARM platforms that didn't have a parsed cpu version
(e.g. arm-none-eabi) would be handled as armv7l-hf-multiplatform which
did break building arm-trusted-platform packages for some targets (e.g.
rk3399).
Using pcBase as fallback, instead of armv7l-hf-multiplatform,
corresponds with the behaviour we had before 40e7be1.
The last use of `kernelMajor` in Nixpkgs was removed in 2018.
Even then, I'm not positive it was actually in an exercised code path.
AFAIUI this is now totally redundant and useless as it really was meant
for the 2.4 -> 2.6 transition.
newlib is the default for most tools when no kernel is provided. Other
exist, but this seems like a safe default.
(cherry picked from commit 8009c20711)
