Re: [PATCH 0 of 2] pci passthrough: support "managed" pci device in xend for libvirt usage

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Jan 17, 2013 at 06:00:56PM +0000, George Dunlap wrote:
> On Thu, Jan 17, 2013 at 5:29 AM, <cyliu@suse.com> wrote:
> 
> > One of our customers requests parallel pci passthrough functionality
> > between xen
> > (xend and libxl) and kvm, including support managed host pci devices. A
> > "managed" pci device will be made assignable before vm start  and reattach
> > to
> > its original dirver after vm shut off.
> >
> > Currently, libvirt supports "managed=yes/no" options in pci device
> > definition.
> > Qemu driver already supports managed pci devices, libxl driver will add
> > that
> > support in libvirt source code. For xend driver, since it's stateful,
> > libvirt
> > can't do much things because libvirt doesn't store much informtion and most
> > work is done by calling xend directly. Even "managed" option won't be
> > stored if
> > xend doesn't support it. For that reason, this patch series tries to add
> > code in
> > xend toolstack to support managed pci devices first, then libvirt can call
> > xend
> > operations directly to support "managed" host pci devices.
> >
> > Syntax for managed pci device could be:
> > pci=['0000:00:1a.0,managed=1']
> >
> > Please share your comments. Thanks!
> >
> 
> The first question (before I look at the code closely) is whether we want
> to accept new features into xend.  It's not being actively maintained, and
> we would like to get rid of it at some point.
> 
> Given that you seem primarily to be using libvirt, after the 4.3 release,
> will there be a strong reason to use xend, instead of just using libxl?
> 
> Note I'm not rejecting it outright; I just think a case needs to be made.

I am actually in favour of adding things in both. There are multiple distros
that are still using Xen 4.1 and some of them have a long life-cycle. Adding in
features that are also reflected in 'xl' looks to be the doing the right
thing for the customers and with the future in mind.

> :-)
> 
>  -George

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