https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115284
--- Comment #12 from Hans-Peter Nilsson <hp at gcc dot gnu.org> --- (In reply to r...@cebitec.uni-bielefeld.de from comment #11) > > --- Comment #10 from Hans-Peter Nilsson <hp at gcc dot gnu.org> --- > >> The failure is even earlier here: in a sparc64-unknown-linux-gnu > >> bootstrap, building a libstdc++ .gch file in stage 2 breaks: > > > > Great, thanks! That means that tricking my pc into believing it's a sparc > > by > > means of using the binfmt machinery that Jeff mentioned in the thread where > > I > > mentioned the revert on gcc-patches, would work. (I don't have the details > > and > > don't remember if I'd actually tried it, certainly not recently; I just know > > about the concept.) > > I can't help but wonder if this wouldn't be a total waste of your time: > considering what the qemu wiki docments for SPARC support > > https://wiki.qemu.org/Documentation/Platforms/SPARC > > seems not too encouraging for 64-bit systems. Thanks for the warning, but I'm confused as it doesn't look too bad to me; for example the status field for SPARC64 says "working" at least for non-historic qemu versions. What am I missing? Are you thinking of something specific there? > When I think about what > it took myself to get recent macOS working on qemu-kvm (although the > procedure is resonably well documented, with firmware and all > available), I'd consider such an attempt a positive nightmare. Also, I wouldn't be using qemu-system-sparc64 IIUC: with the binfmt trick I'd be using qemu-user. That "experience" (assuming success) would also lead to a template or identical solution for other targets, which is the most interesting part. The cfarm is nice to have, but the machines are a bit crowded. > When all it takes for you to either get your ssh client working to > access a ready-made and not too slow SPARC system (or in the worst case, > build OpenSSH from source), I know which route I'd take ;-) A different nightmare, leading to a nightmare of chasing a bootstrap failure on a system I'm not familiar with (referring to solaris on the cfarm machine). > > What's not so great is that the described reproducer is a bootstrap, so the > > debug situation is unpleasant. The first step I'd do, would be to just do a > > cross-build (or native --disable-bootstrap) and just run the testsuite > > before/after the patch-set (or just 933ab59c59bdc1) and see if the problem > > manifests there. > I've tried that now on both > > * sparc-sun-solaris2.11 (c and c++ only): no additional testsuite > failures are apparent there, which is not too astonishing given that > the bootstrap failure occurs in stage 3, suggesting a mis-compiled > stage 2 cc1plus, and Oh, too bad. Thanks for doing that! > * sparc64-unknown-linux-gnu (again, c and c++ only): there are testsuite > failures all over the place, but I'd have to perform another bootstrap > with your patches removed to make an exact comparison. Hm, the part where you compare results against a baseline is pretty central. One the one hand, when it doesn't manifest for sparc64-solaris just through the testsuite, the odds are against it manifesting that simple for sparc64-linux. On the other hand, an existing reproducer is so much easier to handle. Thank you and thanks in advance for the last step!
