[libvirt] [PATCHv2 2/8] doc: schema: Add basic documentation for the virtual RNG device support

[Peter Krempa]

On 02/25/13 22:01, Eric Blake wrote:
> On 02/25/2013 02:08 AM, Peter Krempa wrote:
>> On 02/22/13 19:20, Eric Blake wrote:
>>> On 02/21/2013 07:47 AM, Peter Krempa wrote:
>>>> This patch documents XML elements used for (basic) support of virtual
>>>> RNG devices.
>>>>
>>>>
>>>> For the slightly more advanced EGD backend:
>>>>     <devices>
>>>>       <rng model='virtio'>
>>>>         <backend model='egd' type='udp'>
>>>>           <!-- this is a definition of a character device -->
>>>>           <source mode='bind' service='1234'/>
>>>>           <source mode='connect' host='1.2.3.4' service='1234'/>
>>>>           <!-- or other valid character device configuration -->
>>>
>
>>> Do we really want two <source> in a single <backend> in the example, or
>>> would it be easier to show multiple <rng> devices, one for each type of
>>> backend?
>>
>> That actually is valid for the character device backends. The UDP
>> backend has to use two separate sources for bi-directional
>> communication. The definition of that source type is declared as a type
>> in our RNG schema an I merely reused that.
>
> Oh, I didn't realize that.  Do we want to ENFORCE that there are two
> <source> elements present then?  Or can we always provide a sane default
> when the user provides only 0 or 1 source?  Depending on that answer, it
> might be worth additional documentation on why two <source> elements are
> present, as well as mentioning that order is significant in how they are
> listed.
>
I reused the code to facilitate the operations done with character 
devices. There's present infrastructure [1] that allows to parse, format 
and create commandlines for qemu. The defaults for the syntax of the XML 
and the expected values should be documented in the section describing 
character devices. (But I did not really check if the description is 
exhaustive)

In hindsight I should have linked that section in the description of the 
egd backend model explicitly rather than by just mentioning it.

Peter


[1]: virDomainChrSourceDefParseXML, virDomainChrSourceDefFormat, 
qemuBuildChrChardevStr