[XS] Change in coreboot[main]: util/crossgcc/buildgcc: Compile RISC-V GCC with medany

[Nico Huber (Code Review)]

Attention is currently required from: Felix Held, Felix Singer, Lean Sheng Tan, Martin L Roth, Maximilian Brune.

Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/80139?usp=email )

Change subject: util/crossgcc/buildgcc: Compile RISC-V GCC with medany
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Patch Set 2:

(1 comment)

File util/crossgcc/buildgcc:

https://review.coreboot.org/c/coreboot/+/80139/comment/d3330546_68565af7 :
PS1, Line 779: CFLAGS_FOR_TARGET_EXTRA
> Building using clang works fine. […]

No idea why you'd want to drop libgcc? It's essential for some language
internal things (like 64-bit operations when compiling for 32-bit).

There's a comment in `util/xcompile/xcompile:403` explaining a little about
the Clang situation:
> Right now, the clang reference toolchain is not building compiler-rt builtins
> for any of the cross compile architectures. Hence we use libgcc for now,
> because that is available and lets us proceed with getting coreboot clang
> ready. Toggle CLANG_RUNTIME if you want to experiment with compiler-rt.