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Re: [libvirt] cont command failing via JSON monitor on restore



Jim Fehlig wrote:
> Agreed.  What error do you get back from the text monitor when cont cmd
> fails?  I'd be interested in the following output from
> $root/src/qemu/qemu_monitor_text.c:qemuMonitorCommandWithHandler()
>
>     VIR_DEBUG("Receive command reply ret=%d errno=%d %d bytes '%s'",
>               ret, msg.lastErrno, msg.rxLength, msg.rxBuffer);
>   

Since I cannot reproduce the issue with qemu 0.13 using the text
monitor, I hacked qemu to simulate the error and got the following from
the debug message

Receive command reply ret=0 errno=0 71 bytes 'An incoming migration is
expected before this command can be executed'

msg.lastErrno is 0 (which is why ret is 0), but we've received the "An
incoming migration ..." error message.  The message is available in
reply variable in
$root/src/qemu/qemu_monitor_text.c:qemuMonitorTextStartCPUs(), but
that's not a very robust way to check for error.  Seems qemu should
return an error in addition to the message.  I'm not familiar with the
qemu monitor code, but I suspect the qemu patch you referenced [1] was
insufficient wrt the text monitor.

I think a patch addressing the issue in the JSON monitor, where we can
reliably detect the error, is a good start.  Would that be okay?  Also,
recall that I cannot reproduce the issue with qemu 0.13.  Perhaps other
post-0.12.5 changes have "fixed" the bug in the text monitor.

 
Regards,
Jim

[1] http://lists.gnu.org/archive/html/qemu-devel/2010-07/msg01574.html


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