[libvirt] [PATCH V3 1/2] Intorduce file descriptor set for QEMU domains

[Stefan Berger]

On 02/07/2013 12:58 PM, Daniel P. Berrange wrote:
> On Thu, Feb 07, 2013 at 12:56:45PM -0500, Stefan Berger wrote:
>> On 02/07/2013 10:12 AM, Daniel P. Berrange wrote:
>>> On Mon, Feb 04, 2013 at 07:12:37PM -0500, Stefan Berger wrote:
>>>> Create field in virDomainDeviceInfo structure to hold
>>>> file descriptor set the device is associated with. Have
>>>> the number written into the Device Info XML and parsed
>>> >from the XML.
>>>> Remember the next-toy use file descriptor set in the QEMU
>>>> private domain structure.
>>>> Upon libvirt restart determine the maximum file descriptor
>>>> set used in the Device Info XML and remember the
>>>> next-to-use file descriptor set in the QEMU private domain
>>>> structure.
>>>>
>>>> Upon termination of a domain, reset the next-to-use file
>>>> descriptor set to its initial value '1'.
>>>>
>>>> Stefan Berger <stefanb at linux.vnet.ibm.com>
>>>>
>>>> ---
>>>>   src/conf/capabilities.h |    5 ++++-
>>>>   src/conf/domain_conf.c  |   20 +++++++++++++++++---
>>>>   src/conf/domain_conf.h  |    1 +
>>>>   src/lxc/lxc_domain.c    |    3 ++-
>>>>   src/qemu/qemu_domain.c  |   23 ++++++++++++++++++++++-
>>>>   src/qemu/qemu_domain.h  |    2 ++
>>>>   src/qemu/qemu_process.c |    2 ++
>>>>   7 files changed, 50 insertions(+), 6 deletions(-)
>>> I really don't like the fact that we're modifying the virDomainDef
>>> structs, which are intended to hold static config description, to
>>> also hold QEMU specific dynamic state. We did this in the past
>>> before we had the per-driver 'privateData' associated with
>>> virDomainObjPtr instances.
>> In these patches we are storing the fdset that's in use by a
>> particular device in the virDomainDeviceInfo structure and are
>> persisting that fdset number next to the device's alias into XML
>> written into /var/run/libvirt/qemu to be able to restore it upon
>> libvirt restart. Now we would either need a similar per-device
>> structure in parallel to those virDomainDeviceInfo structures or
>> connect a QEMU private data structure to that virDomainDeviceInfo
>> structure for storing the dynamic data and to keep reference back to
>> the device. Not sure what's the best path ...
> Just have a hashtable mapping device alias names -> fd set numbers
> in the qemuDomainObjPrivatePtr, and write that out in the QEMU
> private XML. There's no need to directly mirror the structs.
>

you agree to this XML ?

   <fdsets>
     <entry alias='ide0-0-0' fdset='1'/>
     <entry alias='serial0' fdset='2'/>
     <entry alias='serial1' fdset='3'/>
   </fdsets>


  Stefan