https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90419
--- Comment #4 from Jim Wilson <wilson at gcc dot gnu.org> --- GCC worked out of the box before we started upstreaming the toolchain. And it will work out of the box again when we are done with the upstreaming. But meanwhile, we are still in the middle of upstreaming and some things only work if you have the right collection of patches or the right collection of source trees. If I change the FSF gcc tree to try to fix this, then I break the github riscv/riscv-gnu-toolchain tree, which is using the same gcc sources, and has working multilib support. I don't want to have to maintain two different gcc source trees, so I'm leaving the FSF gcc broken temporarily because I don't want to break the riscv/riscv-gnu-toolchain tree. This problem will go away when glibc is finished upstreaming. This is a problem I keep raising inside SiFive and the RISC-V Foundation because a number of things are blocked on this glibc upstreaming problem. It isn't clear when it will get fixed though. I might have to volunteer to do it myself at some point, but I'm still hoping someone else does it.