Am 15.05.2016 um 01:13 schrieb Thomas Lamprecht: > Hi all, > > I recently ran into Problems when trying to install some Windows VMs > this was after an update to QEMU 2.5.1.1, the VM shows Windows loading > files for the installation, then the "Starting Windows" screen appears > here it hangs and never continues. > > Changing the "-vga" option to cirrus solves this, the installation can > proceed and finish. When changing back to std (or also qxl, vmware) the > installed VM also hangs on the "Starting Windows" screen while qemu > showing a little but no excessive load. > > This phenomena appears also with QEMU 2.6.0 but not with 2.6.0-rc4, a > git bisect shows fd3c136b3e1482cd0ec7285d6bc2a3e6a62c38d7 (vga: make > sure vga register setup for vbe stays intact (CVE-2016-3712)) as the > culprit for this regression, as its a fix for a DoS its not an option to > just revert it, I guess. > The (short) bisect log is: > > git bisect start > # bad: [bfc766d38e1fae5767d43845c15c79ac8fa6d6af] Update version for v2.6.0 > release > git bisect bad bfc766d38e1fae5767d43845c15c79ac8fa6d6af > # good: [975eb6a547f809608ccb08c221552f666611af25] Update version for > v2.6.0-rc4 release > git bisect good 975eb6a547f809608ccb08c221552f666611af25 > # good: [2068192dcccd8a80dddfcc8df6164cf9c26e0fc4] vga: update vga register > setup on vbe changes > git bisect good 2068192dcccd8a80dddfcc8df6164cf9c26e0fc4 > # bad: [53db932604dfa7bb9241d132e0173894cf54261c] Merge remote-tracking > branch 'remotes/kraxel/tags/pull-vga-20160509-1' into staging > git bisect bad 53db932604dfa7bb9241d132e0173894cf54261c > > I could reproduce that with QEMU 2.5.1 and QEMU 2.6 on a Debian derivate > (Promox VE) with 4.4 Kernel and also with QEMU 2.6 on an Arch Linux > System with a 4.5 Kernel, so it should not be host distro depended. Both > machines have Intel x86_64 processors. > The problem should be reproducible with said Versions or a build from > git including the above mentioned commit (fd3c136) by starting a VM with > an Windows 7 ISO, e.g.: > > Hanging installation > ./x86_64-softmmu/qemu-system-x86_64 -boot d -cdrom win7.iso -m 1024 > > Working installation: > ./x86_64-softmmu/qemu-system-x86_64 -boot d -cdrom win7.iso -m 1024 -vga > cirrus > > Noteworthy may be that Windows 10 is working, I do not had time to get > other Windows versions and test them, I'll do that as soon as possible. > Various Linux system also seems to work fine, at least I did not ran > into an issue there yet. > > I also tried testing with SeaBIOS and OVMF, as initially I had no idea > what broke, both lead to the same result - without the CVE-2016-3712 fix > they both work, with not. > Further, KVM enabled and disabled does not make any difference. > > If I can take any further step, e.g. open a bug report at another place > or help with testing I'd glad to do so. > > best regards, > Thomas
Hi Thomas, thanks for the bug report. I added Gerd to the address list, so I'm sure your report will be noticed. Bugs can be reported at Launchpad (see http://wiki.qemu.org/Contribute/ReportABug). Maybe your report could be posted there, too, so people looking for known problems will find it at the well known location. Cheers Stefan
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