[Qemu-devel] libvirt doesn't work with qemu 1.0

[Qemu-devel] libvirt doesn't work with qemu 1.0

[Gerd Hoffmann]

  Hi,

$subject says all.  The error message is:

error: internal error cannot parse /home/kraxel/bin/qemu-default version
number in 'QEMU emulator version 1.0, Copyright (c) 2003-2008 Fabrice
Bellard'

cheers,
  Gerd

PS: libvirt-0.9.4-23.el6.x86_64

Re: [Qemu-devel] libvirt doesn't work with qemu 1.0

[Anthony Liguori]

On 12/02/2011 08:21 AM, Gerd Hoffmann wrote:
>    Hi,
>
> $subject says all.  The error message is:
>
> error: internal error cannot parse /home/kraxel/bin/qemu-default version
> number in 'QEMU emulator version 1.0, Copyright (c) 2003-2008 Fabrice
> Bellard'

Parsing help output for the version number is a really bad idea.  query-version 
in QMP does the right thing:

(QEMU) query-version
{u'return': {u'qemu': {u'micro': 0, u'major': 1, u'minor': 0}, u'package': ''}}

This is the supported way of figuring out the version number and it's what 
libvirt should be using.

Regards,

Anthony Liguori

>
> cheers,
>    Gerd
>
> PS: libvirt-0.9.4-23.el6.x86_64
>

Re: [Qemu-devel] libvirt doesn't work with qemu 1.0

[Jiri Denemark]

On Fri, Dec 02, 2011 at 08:50:11 -0600, Anthony Liguori wrote:
> On 12/02/2011 08:21 AM, Gerd Hoffmann wrote:
> >    Hi,
> >
> > $subject says all.  The error message is:
> >
> > error: internal error cannot parse /home/kraxel/bin/qemu-default version
> > number in 'QEMU emulator version 1.0, Copyright (c) 2003-2008 Fabrice
> > Bellard'
> 
> Parsing help output for the version number is a really bad idea.  query-version 
> in QMP does the right thing:
> 
> (QEMU) query-version
> {u'return': {u'qemu': {u'micro': 0, u'major': 1, u'minor': 0}, u'package': ''}}

Which of course only works with new enough QEMU that is known to support QMP
(which BTW we detect by checking the version number). Anyway, the fix is easy,
we just need to assume micro is 0 if it's missing instead of requiring it to
be present. A fix will come soon.

Jirka

Re: [Qemu-devel] libvirt doesn't work with qemu 1.0

[Anthony Liguori]

On 12/02/2011 09:08 AM, Jiri Denemark wrote:
> On Fri, Dec 02, 2011 at 08:50:11 -0600, Anthony Liguori wrote:
>> On 12/02/2011 08:21 AM, Gerd Hoffmann wrote:
>>>     Hi,
>>>
>>> $subject says all.  The error message is:
>>>
>>> error: internal error cannot parse /home/kraxel/bin/qemu-default version
>>> number in 'QEMU emulator version 1.0, Copyright (c) 2003-2008 Fabrice
>>> Bellard'
>>
>> Parsing help output for the version number is a really bad idea.  query-version
>> in QMP does the right thing:
>>
>> (QEMU) query-version
>> {u'return': {u'qemu': {u'micro': 0, u'major': 1, u'minor': 0}, u'package': ''}}
>
> Which of course only works with new enough QEMU that is known to support QMP
> (which BTW we detect by checking the version number).

Or you could just try the -qmp option and if QEMU exits, it doesn't support it. 
  That's going to be a lot more reliable than checking a version number.

Regards,

Anthony Liguori

> Anyway, the fix is easy,
> we just need to assume micro is 0 if it's missing instead of requiring it to
> be present. A fix will come soon.
>
> Jirka
>

Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Eric Blake]

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On 12/02/2011 08:15 AM, Anthony Liguori wrote:
>> Which of course only works with new enough QEMU that is known to
>> support QMP
>> (which BTW we detect by checking the version number).
> 
> Or you could just try the -qmp option and if QEMU exits, it doesn't
> support it.  That's going to be a lot more reliable than checking a
> version number.

But we already have to call 'qemu -h' for other reasons; so we might as
well be efficient and learn as much as possible from that result than by
calling both 'qemu -h' and 'qemu -qmp ...', in order to probe what qemu
supports.

Also, 'qemu -qmp' doesn't work.  What's the proper syntax for invoking
qemu in order to query QMP capabilities, but without also starting up a
guest?

At any rate, yes, we want to improve libvirt to cache qemu capabilities,
to do the probing once at startup and then again any time the mtime of
the qemu binary changes, rather than the current policy of doing it on
every VM startup; once we cache information, making multiple probes will
still be more efficient in the long ran than the current probe per guest.

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Anthony Liguori]

On 12/02/2011 01:29 PM, Eric Blake wrote:
> On 12/02/2011 08:15 AM, Anthony Liguori wrote:
>>> Which of course only works with new enough QEMU that is known to
>>> support QMP
>>> (which BTW we detect by checking the version number).
>>
>> Or you could just try the -qmp option and if QEMU exits, it doesn't
>> support it.  That's going to be a lot more reliable than checking a
>> version number.
>
> But we already have to call 'qemu -h' for other reasons; so we might as
> well be efficient and learn as much as possible from that result than by
> calling both 'qemu -h' and 'qemu -qmp ...', in order to probe what qemu
> supports.
>
> Also, 'qemu -qmp' doesn't work.  What's the proper syntax for invoking
> qemu in order to query QMP capabilities, but without also starting up a
> guest?


anthony@titi:~/build/qemu$ (sleep 1; echo -e '{"execute": 
"qmp_capabilities"}\n{"execute": "quit"}') | x86_64-softmmu/qemu-system-x86_64 
-qmp stdio -S -display none | head -1
{"QMP": {"version": {"qemu": {"micro": 94, "minor": 15, "major": 0}, "package": 
""}, "capabilities": []}}

The sleep 1 is due to a bug.  What I would suggest libvirt due is run this 
command but connect to the monitor properly, execute those two commands, and use 
the monitor greeting to figure out the version number.

If you really want a command to invoke, we could also add a command line switch 
that took a QMP command or something like that.

>
> At any rate, yes, we want to improve libvirt to cache qemu capabilities,
> to do the probing once at startup and then again any time the mtime of
> the qemu binary changes, rather than the current policy of doing it on
> every VM startup; once we cache information, making multiple probes will
> still be more efficient in the long ran than the current probe per guest.

That's all well and good but please use the interfaces that we support.

Parsing help output is not the supported way of getting the version.  We happen 
to provide a nice, programmatic and stable interface for getting the version 
information.  Please use it.

Regards,

Anthony Liguori

Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Eric Blake]

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On 12/02/2011 01:32 PM, Anthony Liguori wrote:
>> But we already have to call 'qemu -h' for other reasons; so we might as
>> well be efficient and learn as much as possible from that result than by
>> calling both 'qemu -h' and 'qemu -qmp ...', in order to probe what qemu
>> supports.
>>
>> Also, 'qemu -qmp' doesn't work.  What's the proper syntax for invoking
>> qemu in order to query QMP capabilities, but without also starting up a
>> guest?
> 
> 
> anthony@titi:~/build/qemu$ (sleep 1; echo -e '{"execute":
> "qmp_capabilities"}\n{"execute": "quit"}') |
> x86_64-softmmu/qemu-system-x86_64 -qmp stdio -S -display none | head -1
> {"QMP": {"version": {"qemu": {"micro": 94, "minor": 15, "major": 0},
> "package": ""}, "capabilities": []}}

Doesn't work on 0.12 (the first version with qmp):

$ /usr/libexec/qemu-kvm -qmp stdio -S -display none
qemu-kvm: -display: invalid option
$ /usr/libexec/qemu-kvm -qmp stdio -S -nographic
chardev: opening backend "stdio" failed
qemu: could not open serial device 'stdio': Argument list too long

but if a temporary vnc port is okay, I was indeed able to get a list of
commands.

$ (sleep .1; printf
'{"execute":"qmp_capabilities"}\n{"execute":"query-commands"}\n{"execute":"quit"}\n')
| /usr/libexec/qemu-kvm -qmp stdio -S
VNC server running on `127.0.0.1:5901'
{"QMP": {"version": {"qemu": {"micro": 1, "minor": 12, "major": 0},
"package": "(qemu-kvm-0.12.1.2)"}, "capabilities": []}}
{"return": {}}
{"return": [{"name": "block_stream"}, {"name": "block_job_cancel"}, ...

> 
> The sleep 1 is due to a bug.  What I would suggest libvirt due is run
> this command but connect to the monitor properly, execute those two
> commands, and use the monitor greeting to figure out the version number.
> 
> If you really want a command to invoke, we could also add a command line
> switch that took a QMP command or something like that.

Yes, that would be nice, especially since it would be the sort of patch
that would be worth backporting into distro qemu instances that insist
on staying at 0.12 (yes, I'm looking at RHEL).  That way, libvirt can
automatically decide if qmp is new enough [basically, if qemu is 0.15 or
newer, or if qemu is 0.12 through 0.14 _and_ has hmp passthrough
backported].  In other words, if 'qemu -h' says -qmp-command is
available, and I could run the above as:

qemu-kvm -qmp-command '{"execute":"query-commands"}'

and have qemu automatically fill in the rest, it would be a bit easier
to use.

> Parsing help output is not the supported way of getting the version.  We
> happen to provide a nice, programmatic and stable interface for getting
> the version information.  Please use it.

I'm still stuck with the fact that with everything I tried, 0.12
temporarily opens a VNC port, and that there's a difference between 0.12
(-display none didn't exist) and newer versions; the best would be a
command sequence that works for all versions of qemu that have qmp, and
if it fails, then fall back to -h scraping.

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Paolo Bonzini]

On 01/26/2012 04:55 AM, Eric Blake wrote:
>
> $ /usr/libexec/qemu-kvm -qmp stdio -S -display none
> qemu-kvm: -display: invalid option
> $ /usr/libexec/qemu-kvm -qmp stdio -S -nographic
> chardev: opening backend "stdio" failed
> qemu: could not open serial device 'stdio': Argument list too long

Have you tried -nodefaults?

Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Markus Armbruster]

Paolo Bonzini <pbonzini@redhat.com> writes:

> On 01/26/2012 04:55 AM, Eric Blake wrote:
>>
>> $ /usr/libexec/qemu-kvm -qmp stdio -S -display none
>> qemu-kvm: -display: invalid option
>> $ /usr/libexec/qemu-kvm -qmp stdio -S -nographic
>> chardev: opening backend "stdio" failed
>> qemu: could not open serial device 'stdio': Argument list too long

The "argument list too long" is of course random crap found errno.  The
real cause is trying to create multiple stdio character devices.  The
other one is the -serial stdio you get by default with -nographic and no
default monitor (-qmp suppresses that one).
 
Character device creation error reporting is generally atrocious.  I'm
working on it.

> Have you tried -nodefaults?

That suppresses the default -serial, so it should work.  I always use
it, because our defaults are a labyrinth I can do without.

Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Eric Blake]

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On 01/26/2012 02:41 AM, Paolo Bonzini wrote:
> On 01/26/2012 04:55 AM, Eric Blake wrote:
>>
>> $ /usr/libexec/qemu-kvm -qmp stdio -S -display none
>> qemu-kvm: -display: invalid option
>> $ /usr/libexec/qemu-kvm -qmp stdio -S -nographic
>> chardev: opening backend "stdio" failed
>> qemu: could not open serial device 'stdio': Argument list too long
> 
> Have you tried -nodefaults?

Just did.  It still spawns a VNC server.

$ (sleep .1; printf
'{"execute":"qmp_capabilities"}\n{"execute":"quit"}\n') |\
   /usr/libexec/qemu-kvm -qmp stdio -S -nodefaults
VNC server running on `127.0.0.1:5902'
{"QMP": {"version": {"qemu": {"micro": 1, "minor": 12, "major": 0},
"package": "(qemu-kvm-0.12.1.2)"}, "capabilities": []}}
{"return": {}}
{"return": {}}
{"timestamp": {"seconds": 1327581922, "microseconds": 434736}, "event":
"SHUTDOWN"}

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Paolo Bonzini]

On 01/26/2012 01:46 PM, Eric Blake wrote:
> On 01/26/2012 02:41 AM, Paolo Bonzini wrote:
>> On 01/26/2012 04:55 AM, Eric Blake wrote:
>>>
>>> $ /usr/libexec/qemu-kvm -qmp stdio -S -display none
>>> qemu-kvm: -display: invalid option
>>> $ /usr/libexec/qemu-kvm -qmp stdio -S -nographic
>>> chardev: opening backend "stdio" failed
>>> qemu: could not open serial device 'stdio': Argument list too long
>>
>> Have you tried -nodefaults?
> 
> Just did.  It still spawns a VNC server.
> 
> $ (sleep .1; printf
> '{"execute":"qmp_capabilities"}\n{"execute":"quit"}\n') |\
>     /usr/libexec/qemu-kvm -qmp stdio -S -nodefaults
> VNC server running on `127.0.0.1:5902'
> {"QMP": {"version": {"qemu": {"micro": 1, "minor": 12, "major": 0},
> "package": "(qemu-kvm-0.12.1.2)"}, "capabilities": []}}
> {"return": {}}
> {"return": {}}
> {"timestamp": {"seconds": 1327581922, "microseconds": 434736}, "event":
> "SHUTDOWN"}

What about both? :)

$ (sleep .1; echo $'{"execute":"qmp_capabilities"}\n{"execute":"quit"}') | \
  /usr/libexec/qemu-kvm -qmp stdio -S -nographic -nodefaults
{"QMP": {"version": {"qemu": {"micro": 1, "minor": 12, "major": 0}, "package": "(qemu-kvm-0.12.1.2)"}, "capabilities": []}}
{"return": {}}
{"return": {}}
{"timestamp": {"seconds": 1327582368, "microseconds": 685740}, "event": "SHUTDOWN"}

(I was a bit too terse, -nodefaults is a way to fix the error message,
not the whole mess).

Paolo

Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Luiz Capitulino]

On Wed, 25 Jan 2012 20:55:14 -0700
Eric Blake <eblake@redhat.com> wrote:

> On 12/02/2011 01:32 PM, Anthony Liguori wrote:
> >> But we already have to call 'qemu -h' for other reasons; so we might as
> >> well be efficient and learn as much as possible from that result than by
> >> calling both 'qemu -h' and 'qemu -qmp ...', in order to probe what qemu
> >> supports.
> >>
> >> Also, 'qemu -qmp' doesn't work.  What's the proper syntax for invoking
> >> qemu in order to query QMP capabilities, but without also starting up a
> >> guest?
> > 
> > 
> > anthony@titi:~/build/qemu$ (sleep 1; echo -e '{"execute":
> > "qmp_capabilities"}\n{"execute": "quit"}') |
> > x86_64-softmmu/qemu-system-x86_64 -qmp stdio -S -display none | head -1
> > {"QMP": {"version": {"qemu": {"micro": 94, "minor": 15, "major": 0},
> > "package": ""}, "capabilities": []}}
> 
> Doesn't work on 0.12 (the first version with qmp):

There's another problem lurking here, and I think it's a more serious one:
I don't we are doing proper integration tests with libvirt (we == qemu, but
mostly me).

My tests are sporadic and mostly manual (I used to use libvirt-tck, but it's
been a while since I ran it last time).

Is libvirt-tck the recommended way to run integration tests? If it's we should
be running it frequently.

Re: [Qemu-devel] [libvirt] libvirt doesn't work with qemu 1.0

[Dave Allan]

On Fri, Dec 02, 2011 at 03:21:54PM +0100, Gerd Hoffmann wrote:
>   Hi,
> 
> $subject says all.  The error message is:

Thanks for the heads up.

Dave

> error: internal error cannot parse /home/kraxel/bin/qemu-default version
> number in 'QEMU emulator version 1.0, Copyright (c) 2003-2008 Fabrice
> Bellard'
> 
> cheers,
>   Gerd
> 
> PS: libvirt-0.9.4-23.el6.x86_64
> 
> --
> libvir-list mailing list
> libvir-list@redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list