Re: [libvirt] PATCH: Generic internal API for domain XML parser/formatter
On Wed, Jun 25, 2008 at 10:05:30AM +0200, Gerd Hoffmann wrote:
Daniel P. Berrange wrote:
> In the <graphics> element for VNC we have a 'port' attribute. For a
running
> VM this contains the actual port number. For an inactive VM it contains
> the pre-allocated fixed port number, or -1 to indicate that a automatically
> allocated port should be used.
>
> There is an obvious flaw here - if the VM is running it is impossible to
> tell if its port was fixed or automatically allocated.
Oh, there are some other places where something simliar happens. For
example the network interface target device name, which also can be
either auto-allocated or hardcoded.
We deal with that slightly differently - if we see a target interface
passed in called 'vnetXXXX' or 'vifX.Y' then we ignore it & treat it
as a autogenerated interface.
IMHO it is a fundamental design flaw that dumpxml gives different
results depending on whenever the domain is running or not. Hard to fix
by now though :-(
Actually there is another way to access the info - pass the flag
VIR_DOMAIN_XML_INACTIVE to the DumpXML method to explicitly request
the inactive XML.
If you change the domain config using dumpxml/edit/define while the
domain is running you change the current auto-assigned values into
hardcoded config items as (unwanted) side effect. You can easily end up
with two domains being configured with tap device vnet0 and/or vnc port
5900 without noticing. And then you wounder why trying to start both
domains at the same time doesn't fly ...
With this patch we now correctly handle the the VNC and vnetXX case.
I also fixed the PV text console PTY issue too when we added the full
serial/parallel port support. I'm not aware of any other problems like
this besides these.
Regards,
Daniel.
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