Red Hat Bugzilla – Bug 618332
CPUID_EXT_POPCNT enabled in qemu64 and qemu32 built-in models.
Last modified: 2014-07-24 23:46:00 EDT
Description of problem:
Upstream qemu commit 910628f39676ee65211727245809eec7ca4d75f5 adds
POPCNT to qemu64/qemu32. This can break migration when using
these guest models should migration be attempted to a cpu lacking
# /usr/libexec/qemu-kvm -cpu ?dump
x86 [qemu64] QEMU Virtual CPU version 0.12.1
feature_ecx 00802001 (popcnt cx16 pni|sse3)
x86 [qemu32] QEMU Virtual CPU version 0.12.1
feature_ecx 00800001 (popcnt pni|sse3)
"popcnt" should not be present.
The addition of popcnt to what is intended as a least common
denominator seems rather odd, as only select CPUs support this
feature. This was specifically enabled by the commit called
out above and understanding what motivated this change needs
to be part of the case resolution.
This issue has been proposed when we are only considering blocker
issues in the current Red Hat Enterprise Linux release.
** If you would still like this issue considered for the current
release, ask your support representative to file as a blocker on
your behalf. Otherwise ask that it be considered for the next
Red Hat Enterprise Linux release. **
Not just popcnt, the other flags should be reviewed against hardware in the field.
Tested with qemu-kvm-0.12.1.2-2.108.el6,
1. # /usr/libexec/qemu-kvm -cpu ?dump
x86 cpu64-rhel5 QEMU Virtual CPU version (cpu64-rhel5)
feature_ecx 00000001 (pni|sse3)
x86 cpu64-rhel6 QEMU Virtual CPU version (cpu64-rhel6)
feature_ecx 00002001 (cx16 pni|sse3)
2. Boot guest with -M rhel6.0.0 & -M rhel5.5.0 & -M rhel5.4.4 & -M rhel5.4.0, guest can be boot up successfully with related cpu model.
# /usr/libexec/qemu-kvm -m 4G -smp 2 -monitor stdio -drive file=/home/RHEL-Server-6.0-64-virtio.qcow2,if=none,format=qcow2,boot=on,cache=none,id=test -device virtio-blk-pci,drive=test -device virtio-net-pci,mac=20:20:20:12:23:15,netdev=hostnet0 -netdev tap,script=/etc/qemu-ifup,vhost=on,id=hostnet0 -usbdevice tablet -vnc :10 -M xxxx
Based on above, change status to verified.
Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.