[Libvir] [RFC] Device attach/detach on virsh
Daniel Veillard
veillard at redhat.com
Thu May 10 16:50:40 UTC 2007
On Thu, May 10, 2007 at 06:50:53PM +0900, Masayuki Sunou wrote:
> I want to add I/F to do attach/detatch of VIF and VBD to virsh with
> virDomainAttachDevice()/virDomainDetachDevice().
> And, I have two proposals about I/F for virsh to do attach/detach of VIF and VBD.
>
> proposal 1:
> Virsh catches MAC, bridge name, device name (physical,virtual), and another
> by the command option.
[...]
> <advantage>
> - I/F is easy to use than proposal 1. (Because the user does not have to
> make XML)
> <disadvantage>
> - I/F increases because I/F of VIF and VBD becomes separate. (So, the
> addition of I/F is necessary at any time for supporting devices other
> than VIF and VBD. )
> - Handling of optional analysis, handling of XML making are necessary
> in virsh.c, and processing becomes complicated.
To me this proposal is not okay as-is because it looks completely tied to
Xen. But maybe I didn't understand, suppose I use KVM what would be the vbd
or vif parameter looking like ? We need at least to change the terminology
i.e. replace vif and vbd terms, but I'm afraid
One important problem is naming, suppose you want to remove a network
device, how will you name that device ? Using a vif Xen device number is
not proper in my opinion it makes it really hard for the user (i.e. you
have to dig in Xen internal to find the number).
>
> proposal 2:
> virsh catches a definition of a device by XML
>
> ex)
> ------------------------------------------------------------------
> # virsh help attach(detach)-device
> NAME
> attach(detach)-device - attach(detach) device from an XML file
>
> SYNOPSIS
> attach(detach)-device <domain> <file>
>
> DESCRIPTION
> Attach(Detach) device from an XML <file>
>
> OPTIONS
> <domain> domain name, id or uuid
> <file> XML file of device description
> ------------------------------------------------------------------
>
> <advantage>
> - I/F is unified without affecting a device type. (I/F is simple)
> - Handling of virsh.c is simple. (Optional analysis is not necessary)
> <disadvantage>
> - The user has to describe XML.(It is troublesome)
>
>
> I think that specifications that a user is easy to use (proposal 1)
> are better.
> Please, give me an opinion which proposal is better.
it looks to me that only proposal 2 is not tied to a given engine and
would work even if we add very different system with more complex devices.
But I agree it's not perfect from a user point of view either.
Daniel
--
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard | virtualization library http://libvirt.org/
veillard at redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/
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