* Paolo Bonzini (pbonzini(a)redhat.com) wrote:
host-passthrough documentation menions that the source and
destination
hosts are not identical in both hardware and configuration. Configuration
actually includes microcode version and QEMU version, but this is not
clear so make it explicit
Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com>
---
docs/formatdomain.html.in | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index f5c882141a..6d084d7c04 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1590,8 +1590,8 @@
hand, the ABI provided to the guest is reproducible. During
migration, complete CPU model definition is transferred to the
destination host so the migrated guest will see exactly the same CPU
- model even if the destination host contains more capable CPUs for
- the running instance of the guest; but shutting down and restarting
+ model for the running instance of the guest, even if the destination
+ host contains more capable CPUs or newer kernel; but shutting down and
restarting
the guest may present different hardware to the guest according to
the capabilities of the new host. Prior to libvirt 3.2.0 and QEMU
2.9.0 detection of the host CPU model via QEMU is not supported.
@@ -1625,10 +1625,10 @@
environment cannot be reproduced on different hardware. Thus, if you
hit any bugs, you are on your own. Further details of that CPU can
be changed using <code>feature</code> elements. Migration of a
guest
- using host-passthrough is dangerous if the source and destination
- hosts are not identical in both hardware and configuration. If such
- a migration is attempted then the guest may hang or crash upon
- resuming execution on the destination host.</dd>
+ using host-passthrough is dangerous if the source and destination hosts
+ are not identical in both hardware, QEMU version, microcode version
+ and configuration. If such a migration is attempted then the guest may
+ hang or crash upon resuming execution on the destination host.</dd>
If libvirt is driving qemu with 'exact' on the cpu option, under what
situation would it hang/crash on the destination?
All of the microcode changes I think have caused a flag to appear, and
thus it would be required on the destination.
Dave
</dl>
Both <code>host-model</code> and
<code>host-passthrough</code> modes
--
2.21.0
--
Dr. David Alan Gilbert / dgilbert(a)redhat.com / Manchester, UK