Re: [Xen-devel] [BUG] libxenstat and xentop confused by renamed VIF interfaces

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-05-21 at 13:35 +0200, Jacek Konieczny wrote:
> On 05/21/14 12:29, Ian Campbell wrote:
> > On Wed, 2014-05-21 at 09:52 +0200, Jacek Konieczny wrote:
> >> I think the solution would be to look-up the actual interface name or
> >> index in sysfs, e.g. under /sys/devices/vif-${domind}-*.
> > 
> > Sounds plausible.
> > 
> > Or perhaps check that /sys/class/net/${dev}/device/devtype contains
> > "vif"? Might want to handle tap devices too.
> 
> I am not sure we could easily map a renamed tap (can they be renamed?)

I think so, to ${vifname}-emu IIRC.

> device to a domid.

True.

> > Perhaps parse the content of /sys/class/net/vif1.0/device/nodename to
> > get the domid and devid?
> 
> I think I could prepare the patch.

Thank you!

> One question: can I assume /sys is always mounted and the
> '/sys/.../device/nodename', contains 'backend/vif/$domid/*' or should
> there be a fall-back to the old behaviour?

I think on Linux we can assume these days that /sys must exist. I'm less
sure about the content of nodename, in particular WRT the behaviour of
the classic-Xen forward ports. (Jan, CCd, might know).

I'd be inclined to keep the existing code as a fallback for now, I
think.

> BTW, when 'device/nodename' exists and contains 'backend/vif/*' we don't
> need to check 'device/devtype' â one file access less.

Ack.

Ian.


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