[Libvir] Re: support for hvm guests

[Anthony Liguori]

Jim Fehlig wrote:
> Daniel Veillard wrote:
>
>> On Wed, May 03, 2006 at 09:43:36AM -0600, Jim Fehlig wrote:
>>  
>>
>>> Currently I can get info on hvm domains but unable to create them.  
>>> The create request is sent to xend but then blocks reading from xend 
>>> in xend_req().  No problem creating the domain using xm.  I have 
>>> looked at the config coming into xend and it is identical between xm 
>>> and virsh/libvirt.  Need to poke around xend and see why there is no 
>>> response to the virsh/libvirt create request for hvm domains.
>>>   
>>
>>  Hum, basically to debug this kind of things I spend my time in
>> /var/log/xend.log especially since it prints what it received at 
>> creation
>> time, you can at least check the informations coming from libvirt and
>> from xm look alike.
>>  Unfortunately I won't be able to help you, first because I'm about to
>> take vacations for 3 weeks :-), second because I don't have one of those
>> new Intel CPUs, but I am sure others will give an hand if needed.
>>  
>>
>
> Well, I have found the problem but not a fix :-).  When posting the 
> create op to xend, the libvirt code currently waits for a response 
> from xend (xend_req() is called after posting in xend_post()).  For 
> hvm guests, xend does not respond and libvirt blocks indefinitely on 
> read.  If I skip over the call to xend_req() for the create operation, 
> wait_for_devices() and subsequently unpause() are called and the hvm 
> guest is launched.

What do you mean by Xend does not respond?

The path is a normal domain_create().  The path within Xend is 
server/XMLRPCServer.py but that's a very thin wrapper around a direct 
call to XendDomain.py:domain_create().  domain_create() should always 
return.  If it's not, there's a bug in Xend I think.

Can you give me a very concrete test case for this?  The exact 
parameters being passed to domain_create() (it should just be an 
S-Expression config).

Regards,

Anthony Liguori

> This "fix" is just an experimental hack and an appropriate fix would 
> be to have xend respond to the create op for hvm guests.  Being 
> unfamiliar with the xend code, perhaps someone (Anthony :-)) could 
> direct me to the appropriate module in xend?  Recall that all of this 
> works for paravirtualized guests so it may not be hard to find even 
> for someone that has just dabbled in the code.
>
> Regards,
> Jim
>