23.09.2014 18:40, Michael Tokarev wrote: > It boils down to just this: > > qemu-system-x86_64 -enable-kvm -kernel /tmp/xen-4.1-amd64 -initrd > /boot/vmlinuz-$(uname -r) -cpu host > > (where /tmp/xen-4.1-amd64 is the regular xen hypervisor, from > /boot/xen-4.1-amd64.gz, > just uncompressed; -cpu host is not mandatory, but you'll see why I used it > in a moment). > > So the above command fails with this 8254 timer not connected message. But > this: > > qemu-system-x86_64 -enable-kvm -kernel /tmp/xen-4.1-amd64 -initrd > /boot/vmlinuz-$(uname -r) -cpu host,-x2apic > > works fine (it fails down the line for me because I used kernel which is not > capable > of running as a dom0 but that's obviously a different issue). > > There's another data point. This: > > qemu-system-x86_64 -enable-kvm -kernel /tmp/xen-4.1-amd64 -initrd > /boot/vmlinuz-$(uname -r) -M pc-i440fx-1.7 > > works, while this: > > qemu-system-x86_64 -enable-kvm -kernel /tmp/xen-4.1-amd64 -initrd > /boot/vmlinuz-$(uname -r) -M pc-i440fx-2.0 > > fails. So basically, x2apic in 2.0 behaves wrongly here (from xen PoV > anyway), > while x2apic in 1.7 (and also 1.5 and some other previous versions) worked > fine.
One more data point about all this. This bugreport says that 2.0 version of qemu is affected, and the above test shows that previous versions are not affected. The problem in 2.0 is that since 2.0, x2apic is turned on by default, while in previous versions it weren't. The same command as above, but with -cpu whatever,-x2apic will work too, the same way as all previous versions worked, and as shown by second command above. Thanks, /mjt > As Michael Tsirkin said, "I know our x2apic is somewhat unusual but I forgot > the details. > I think at this point it will be easier for the xen guys to debug". > > So here it goes.. ;) -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
