ld.bfd requires an explicit emulation for MIPS for ld -r.

[jhb]

Test Plan

• build mips64 with mips-gcc6 toolchain (32-bit mips builds fine)

[jhb]

• Fixup to MIPS ld flags.

[emaste]

Hmm, I guess it is what it is. I presume we don't need ld emulation anywhere else?

[jhb]

MIPS is kind of special as we use the same toolchain for multiple ABIs whereas for most other platforms we use a dedicated toolchain for each ABI where the default ABI matches. lld is a bit better about this as it will infer the emulation from the object files. If powerpc were fixed to use a shared GCC toolchain for powerpc and powerpc64 it would probably need this, similar to if we had a shared amd64/i386 GCC.

[emaste]

@jhb thanks for the info, although I meant are there other places we're passing -m <emulation> (which presumably need or already have something similar) rather than are there other archs that would need it.

[jhb]

In D25728#578014, @emaste wrote:

@jhb thanks for the info, although I meant are there other places we're passing -m <emulation> (which presumably need or already have something similar) rather than are there other archs that would need it.

The kernel uses an explicit LD for the link of the kernel itself and we have LD_EMULATION_<machine_arch> helper variables in kern.post.mk IIRC to deal with that. I think we also use those for some of the firmware blob stuff. We mostly avoid explicit LD though (and arguably we should avoid it whenever possible, though ld -r is a case we can't use the compiler driver to do)