Jeff Law <l...@redhat.com> writes: > On 01/06/2013 03:56 PM, "Jürgen Urban" wrote: >> Hello, >> >> I created a patch from scratch to support MIPS r5900 used in the >> Playstation 2, but I have some problems with it. The attached patch >> only works with the latest binutils from CVS. The binutils forces the >> compiler to use r5900 compatible instructions which is good to find >> errors in the GCC. Later I will try to submit a patch here, but first >> I need some help. The MIPS r5900 supports 32 bit, 64 bit and 128 bit >> data accesses on a 32 Bit address bus. It supports instructions from >> MIPS ISA I, II, III, IV and has additional instructions, but none of >> them are complete. On each ISA level there are instructions missing. >> It can run MIPS ABI o32, n32 and o64 code, as long as unsupported >> instructions are not used or emulated by the operating system and the >> addresses keep in the first 32 bit. My patch adds support for r5900 >> and tries to disable the following unsupported instructions: ll, sc, >> dmult, ddiv, cvt.w.s, 64 bit FPU instructions. ll and sc is disabled >> with "-mno-llsc" and works. cvt.w.s is replaced by trunc.w.s. This >> seems to work. I disabled 64 bit FPU instructions by "-msoft-float". >> This works, but using "-msingle-float" fails. This would be the >> better configuration. There are still 64 bit FPU instructions used >> (e.g. "dmfc1 $2,$f0" when using "long double" multiplication). So >> "-msingle-float" doesn't seem to work on generic mips64-linux-gnu. I >> tried to disable dmult and ddiv (see mips.md). Disabling worked, but >> now muldi3 calls itself in libgcc2. I thought this should work, >> because I got this working with GCC 4.3, but the latest GCC version >> is a problem. multi3 is calling muldi3, so that muldi3 should be able >> to use mulsi3, because it is the same C code in libgcc2. Can someone >> get me some hints or comments? How can this be debugged? >> >> Does someone know how to enable TImode in MIPS ABI o32 (this doesn't >> need to use the 128 bit instructions at the moment)? There is some >> old code for the Playstation 2 which needs this. I know that TImode >> is supported in ABI n32, but some code uses also the 32 bit FPU and >> FPU registers are not available with "-msoft-float" in inline >> assembler. >> >> What is the best way to change the alignment to 128 bit for all >> structures and stack in any MIPS ABI? Much old code for the >> Playstation 2 expects this. > Hmm, I did a R5900 port back in the late 90s... Did that port never get > contributed (yes, my memory is that bad these days)
I remember there was talk in the early 2000s of contributing it, but we never had time. I think the MIPS copro support was from the r5900 port -- so it's effectively dead at the moment -- and the MODE_HAS_* stuff was from a refresh of it. Both of those made their way in, but I think that was about it. Richard
