On 08/11/17 02:39, Laszlo Ersek wrote: > On 08/10/17 16:54, Laszlo Ersek wrote: >> On 08/10/17 14:15, Laszlo Ersek wrote: >> >>> So I think it comes down to another toolchain difference between RHEL-7 >>> and Fedora-26. Likely gcc -- the commit you identified is also related >>> to a C compiler. In particular: >>> >>> - on RHEL-7, the system compiler (gcc-4.8.5) is mapped to the "GCC48" >>> toolchain settings of edk2, which lack support for LTO (link time >>> optimization), >>> >>> - in the Fedora package's SPEC file, the "GCC49" toolchain settings are >>> selected for the build in a fixed manner, which also lack support for >>> LTO, >>> >>> - in kraxel's SPEC file, Fedora-26's gcc-7 compiler is mapped to the >>> "GCC5" toolchain settings, which *enable* LTO (for DEBUG). >>> >>> The test you suggested to David elsewhere in this thread confirms that >>> the Fedora -- well, "virt-preview" -- package, built with GCC49 >>> settings, works, and that Gerd's package, built with GCC5 settings, >>> breaks. >>> >>> I'll spin up a Fedora-26 guest and build OVMF there. >> >> I confirm that building with gcc-7.1.1 on Fedora-26, using the GCC5 >> toolchain settings and the DEBUG target (= optimizations enabled), the >> problem reproduces for me. >> >> Keeping everything the same except switching DEBUG to NOOPT (= >> optimizations disabled) the OVMF binary returns to working state. >> >> So, OVMF is being mis-built / mis-optimized by gcc-7.1, with the DEBUG >> GCC5 settings. I'll try to tweak both the code and the gcc flags. > > Posted a patch (and CC'd you on it): > > https://lists.01.org/pipermail/edk2-devel/2017-August/013125.html > > Testing would be appreciated. Instructions are in the linked message. > > If you reply to edk2-devel, please subscribe first (and wait for the > subscription to complete), otherwise the list will drop your email. It's > bad and I've tried to change it, but so far I've failed. > <https://bugzilla.tianocore.org/show_bug.cgi?id=451>
Thank you Alex for the bisection and for testing the v1 patch. The v2 patch has been pushed to the edk2 repo: https://bugzilla.tianocore.org/show_bug.cgi?id=657#c10 Thanks Laszlo _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://www.redhat.com/mailman/listinfo/vfio-users
