I've updated the instructions on the gist. The good news is that the bootstrap process now finishes without errors. The bad news is that TIL that LLVM's libunwind doesn't support MIPS :-/. This means that you won't be able to use unwinding at all in your programs if you use this statically linked version of the mips-musl target. The other bad news is that I can't build "hello world" with the bootstrapped rustc. I get linker errors about undefined references to libunwind functions. These errors may go away if I stub the missing functions like this patch does though.