On Mon, Sep 02, 2024 at 11:49:43AM +0200, Vitaly Kuznetsov wrote: > Yan Zhao <yan.y.zhao@xxxxxxxxx> writes: > > > On Fri, Aug 30, 2024 at 03:47:11PM +0200, Vitaly Kuznetsov wrote: > >> Gerd Hoffmann <kraxel@xxxxxxxxxx> writes: > >> > >> >> Necroposting! > >> >> > >> >> Turns out that this change broke "bochs-display" driver in QEMU even > >> >> when the guest is modern (don't ask me 'who the hell uses bochs for > >> >> modern guests', it was basically a configuration error :-). E.g: > >> > > >> > qemu stdvga (the default display device) is affected too. > >> > > >> > >> So far, I was only able to verify that the issue has nothing to do with > >> OVMF and multi-vcpu, it reproduces very well with > >> > >> $ qemu-kvm -machine q35,accel=kvm,kernel-irqchip=split -name guest=c10s > >> -cpu host -smp 1 -m 16384 -drive file=/var/lib/libvirt/images/c10s-bios.qcow2,if=none,id=drive-ide0-0-0 > >> -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 > >> -vnc :0 -device VGA -monitor stdio --no-reboot > >> > >> Comparing traces of working and broken cases, I couldn't find anything > >> suspicious but I may had missed something of course. For now, it seems > >> like a userspace misbehavior resulting in a segfault. > > Could you please share steps launch the broken guest desktop? > > (better also with guest kernel version, name of desktop processes, > > name of X server) > > I think the easiest would be to download the latest Centos Stream 10 > iso, e.g: > > https://composes.stream.centos.org/stream-10/development/CentOS-Stream-10-20240902.d.0/compose/BaseOS/x86_64/iso/CentOS-Stream-10-20240902.d.0-x86_64-dvd1.iso > (the link is probably not eternal but should work for a couple weeks, > check https://composes.stream.centos.org/stream-10/development/ it it > doesn't work anymore). > > Then, just run it: > $ /usr/libexec/qemu-kvm -machine q35,accel=kvm,kernel-irqchip=split -name guest=c10s -cpu host -smp 1 -m 16384 -cdrom CentOS-Stream-10-20240902.d.0-x86_64-dvd1.iso -vnc :0 -device VGA -monitor stdio --no-reboot > > and connect to VNC console. To speed things up, pick 'Install Centos > Stream 10' in the boot menu to avoid ISO integrity check. > > With "KVM: VMX: Always honor guest PAT on CPUs that support self-snoop" > commit included, you will see the following on the VNC console: > installer tries starting Wayland, crashes and drops back into text > console. If you revert the commit and start over, Wayland will normally > start and you will see the installer. Hmm, looks this issue can't be reproduced on physical machine "Coffee Lake-S". The installer can show up to ask for language selection. But it can be reproduced on the machine "Sapphire Rapids XCC". > If the installer environment is inconvenient for debugging, then you can > install in text mode (or with the commit reverted :-) and then the same > problem will be observed when gdm starts. > Same to the gdm. > FWIW, I use QEMU-9.0 from the same C10S (qemu-kvm-9.0.0-7.el10.x86_64) > but I don't think it matters in this case. My CPU is "Intel(R) Xeon(R) > Silver 4410Y". Will have a debug to check what's going wrong. Thanks!
