Hi Fredrik, > Many thanks for your review, Maciej,
You are welcome! > > Eventually you'll have to remove all these instructions (plus LL and SC) > > from the system emulation mode. In fact I think it would make sense to do > > that right away, because I believe it will be a reasonably simple update. > > However if it turns out to be a can of worms after all, then I think we > > can defer it, because we do not have a bare-metal environment ready for > > this CPU anyway (or do we?). > > Indeed, very simple. I added a new check function check_insn_opc_user_only, > similar to check_insn_opc_removed, conditional on USER_ONLY and so a simple > > check_insn_opc_user_only(ctx, INSN_R5900); > > has to be added for these OPC cases. To test this I tried to build GCC with > the target mips64r5900el but it unfortunately didn't work as GCC failed to > compile itself: > > ../sysdeps/mips/mips64/mul_1.S:49: Error: opcode not supported on > this processor: r5900 (mips3) `dmultu $8,$7' That file is a part of GMP rather that GCC I believe. A copy is used by glibc too. I think you'll have to arrange for GMP and glibc builds to avoid this file for R5900 targets, either by supplying a handcoded R5900 assembly alternative that avoids the missing instruction (possibly by using a sequence of MULTU operations), or by using the generic C-language version from mul_1.c. I wouldn't recommend placing an architecture override within the generic 64-bit MIPS assembly so as to force it to build, as any kernel DMULTU emulation is bound to be slower, because it'll have to do all that we need to do here anyway, and then it'll add the overhead of calling an exception handler. I suspect there will be more such cases to handle in GMP and glibc. As GMP holds the master copies of code you'll need to submit any updates to that project first, and once accepted they can be carried over to glibc. As I suggested before you may wish to focus on making o32 work first rather than keeping being distracted by 64-bit issues, so that we have at least some functional code upstream before diving into enhancements and corner cases. HTH, Maciej
