However, On 7/13/20 4:19 PM, Hans van Kranenburg wrote: > (Adding more To:; Note that mailing the bug number does not make it end > up at the submitter automatically, only the package maintainer). > > Hi Christian, > > thanks for the hints! > > On Mon, 13 Jul 2020 09:01:18 +0200 Christian Ehrhardt > <christian.ehrha...@canonical.com> wrote: >> Hi, >> I was seeing the bug updates flying by and just wanted to mention that we >> have seen something similar in Ubuntu - but back then things weren't >> replicable on Debian so we couldn't contribute things back. >> It seemed to be due to the newer and different-defaults toolchain that we >> had in Ubuntu at the time. >> >> But here qemu/xen crashes + new toolchain come together again which >> reminded me. >> >> So without any promises that it really is related I wanted to FYI you to >> these two fixes we needed for Xen: >> https://git.launchpad.net/ubuntu/+source/xen/tree/debian/patches/1001-strip-note-gnu-property.patch?h=ubuntu/groovy-devel > > I guess this first one would be one needed? "Force fcf-protection off > when using -mindirect-branch". > > In that case want this one, it's not backported to 4.11-stable: > > "x86/build: Unilaterally disable -fcf-protection" > > https://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=3a218961b16f1f4feb1147f56338faf1ac8f5703
However, this is a workaround for a gcc bug that is fixed in: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=a03efb266f This fix is included in gcc-9 in Debian since 9.3.0-12: https://salsa.debian.org/toolchain-team/gcc/-/blob/gcc-9-debian/debian/changelog#L55 (it's the PR target/93654 (x86)) Reporter says the 4.11.4-1 package is used, which is built using gcc 9.3.0-13: https://buildd.debian.org/status/fetch.php?pkg=xen&arch=all&ver=4.11.4-1&stamp=1590602099&raw=0 >> https://git.launchpad.net/ubuntu/+source/xen/tree/debian/patches/1000-flags-fcs-protect-none.patch?h=ubuntu/groovy-devel > > This one is about the build failing. > >> This would seem more applicable if the new toolchain would have recently >> rebuilt xen and not qemu as in this case. But as an FYI it is still worth a >> ping. > > 小太, can you do... > > xl create -vvv <domU.cfg> > > ...which should show how qemu is invoked. Can you show that command? > > I can provide you with some test packages with the mentioned upstream > patch applied (on top of 4.11.4+24-gddaaccbbab-1), so you can test if > your domU starts with them. > > If so, we can request the backport upstream and/or maybe pick it for > Debian 4.11 into the patch queue, whatever happens earlier. So, the above info tells us that this probably is not the issue that we're looking at. (I'm fine with still making some test packages for reporter to test with to 100% check this.) Then, let's see what shows up in the xl -vvv output and if there's anything that can be debugged when starting the qemu process with those args? > Thanks, > Hans (Debian Xen Team) >
