Date: Sun, 31 May 2020 00:57:12 +0000 From: Will Springer <skirmisher@...tonmail.com> To: Segher Boessenkool <segher@...nel.crashing.org>, linuxppc-dev@...ts.ozlabs.org Cc: libc-alpha@...rceware.org, eery@...erfox.es, daniel@...aforge.org, musl@...ts.openwall.com, binutils@...rceware.org, libc-dev@...ts.llvm.org Subject: Re: ppc64le and 32-bit LE userland compatibility On Saturday, May 30, 2020 12:22:12 PM PDT Segher Boessenkool wrote: > The original sysv PowerPC supplement > http://refspecs.linux-foundation.org/elf/elfspec_ppc.pdf > supports LE as well, and most powerpcle ports use that. But, the > big-endian Linux ABI differs in quite a few places, and it of course > makes a lot better sense if powerpcle-linux follows that. Right, I should have clarified I was talking about Linux ABIs specifically. > What patches did you need? I regularly build >30 cross compilers (on > both BE and LE hosts; I haven't used 32-bit hosts for a long time, but > in the past those worked fine as well). I also cross-built > powerpcle-linux-gcc quite a few times (from powerpc64le, from powerpc64, > from various x86). There was just an assumption that LE == powerpc64le in libgo, spotted by q66 (daniel@ on the CC). I just pushed the patch to . > Almost no project that used 32-bit PowerPC in LE mode has sent patches > to the upstreams. Right, but I have heard concerns from at least one person familiar with the ppc kernel about breaking existing users of this arch-endianness combo, if any. It seems likely that none of those use upstream, though ^^; > The ABI says long longs are passed in the same order in registers as it > would be in memory; so the high part and the low part are swapped > between BE and LE. Which registers make up a pair is exactly the same > between the two. (You can verify this with an existing powerpcle-* > compiler, too; I did, and we implement it correctly as far as I can > see). I'll give it a closer look. This is my first time poking at this sort of thing in depth, so excuse my unfamiliarity! > A huge factor in having good GCC support for powerpcle-linux (or > anything else) is someone needs to regularly test it, and share test > results with us (via gcc-testresults@). Hint hint hint :-) > > That way we know it is in good shape, know when we are regressing it, > know there is interest in it. Once I have more of a bootstrapped userland than a barely-functional cross chroot, I'll get back to you on that :) > gl;hf, > > > Segher Thanks, Will [she/her] : https://github.com/Skirmisher/void-packages/blob/master/srcpkgs/gcc/patches/libgo-ppcle.patch
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