[libvirt] XML support for arbitrary command line arguments

[Venkateswararao Jujjuri (JV)]

On 9/21/2010 10:02 AM, Daniel P. Berrange wrote:
> On Mon, Sep 20, 2010 at 04:07:32PM -0700, Venkateswararao Jujjuri (JV) wrote:
>> On 9/14/2010 9:34 AM, Venkateswararao Jujjuri (JV) wrote:
>>> On 9/14/2010 2:43 AM, Daniel P. Berrange wrote:
>>>> On Tue, Sep 14, 2010 at 11:03:04AM +0530, Harsh Bora wrote:
>>>>> As QEMU provides support for accessing such shared directory with the
>>>>> help of 9p server, and therefore need to be passed additional
>>>>> commandline argument while starting, I wanted to test it using XML and
>>>>> libvirt.
>>>>
>>>>> So, if the idea looks good to everyone, we can have something like:
>>>>>
>>>>> <shareddir fstype=local path='/folder/to/share' mount_tag='unique_tag'
>>>>> security_model='as_applicable'>
>>>
>>> fstype may not be 'local' all the time. So in the XML description, I would
>>> propose something like
>>> fstype='filesystem type' or something like that. For now only QEMU
>>> supports local.
>>> This keyword represents all local filesystems like ext3/ext4 etc.
>>>>
>>>> We already have an XML syntax defined for filesystems using
>>>> the<filesystem>  element. I've proposed an impl for QEMU using
>>>> p9fs before, but we didn't apply it yet.
>>>>
>>>> http://www.redhat.com/archives/libvir-list/2010-July/msg00458.html
>>
>>
>> Taking a closer look at the Danial's patch above, it covers almost all our
>> needs.
>> Except that the fstype and security models are hard coded.
>
> fstype is hardcoded to local only in so much as there aren't
> any other options in QEMU for fstype. If QEMU adds other
> fstype options, we'll extend<filesystem type='XXXX'>  to
> cover them. Currently type='bind' in the XML maps to fstype=local
> in QEMU.

local is the only option now. But we expect it to have more options sooner if
not later. It will be great if there is a way we can make it a tag/variable in 
this attempt.
If you think it is better to deal with it later..sure we can live with that. :)

>
>>
>> +    virBufferAddLit(&opt, "local,security_model=mapped");
>>
>> Any reason why it was not taken yet?
>
> I wanted to decide on best setting for security model. I think it
> might be better to make it use passthrough by default, since that
> gives better interoperability for users with matching host/guest
> IDs.

Sure passthrough is the most compatible option. Can you please explain
what do you mean by "best setting"? you mean the tag name?
Can we introduce new tags for security_mode and fstype(instead of overloading 
type=bind)?

Thanks,
JV

>
> Daniel