[PATCH v5 0/5] Allow ld.lld to link the MIPS VDSO

[Nathan Chancellor]

Hi all,

This series allows ld.lld to properly and completely link the MIPS vDSO.

Patch 1 adds ld.lld support to Kconfig so that we can avoid certain
ld.bfd checks.

Patch 2 moves disabling of the VDSO to Kconfig. This allows us to avoid
a warning with LD=ld.lld during the clean phase, when we do not have
access to CONFIG_LD_IS_LLD.

Patch 3 prepares for the shift from $(CC) to $(LD) and is probably a
worthwhile change aside from this series because GCC 4.6 is the minimum
version allowed to build the kernel.

Patch 4 does the actual shift from $(CC) to $(LD) to link the VDSO.

Patch 5 allows LD=ld.lld to build the VDSO fully through Kconfig.

I have build tested 32r2_defconfig, 32r2el_defconfig, 64r2_defconfig,
and 64r2el_defconfig with GCC and 32r2el_defconfig and
malta_kvm_guest_defconfig with clang. There is a separate issue with the
64-bit configs (https://github.com/ClangBuiltLinux/linux/issues/884) and
ld.lld does not support the triple OUTPUT_FORMAT linker script macro so
32r2_defconfig errors out in a manner similar to GCC without patch 3:
https://github.com/llvm/llvm-project/blob/46a75436f811d0e6a2c76c669140a7e9471cd2a3/lld/ELF/ScriptParser.cpp#L430
TODO: File an LLVM bug upstream

Please let me know if there are any issues!

Cheers,
Nathan