Re: [libvirt] [PATCH] Add support for 'passthru' mode for direct network interfaces

On 05/11/2011 08:21 AM, Daniel P. Berrange wrote: >On Tue, May 10, 2011 at 04:21:29PM -0600, Eric Blake wrote: >>On 05/10/2011 05:59 AM, D. Herrendoerfer wrote: >>>Hi all, >>> >>>starting with kernel 2.6.38 macvtap supports a 'passthru' mode for >>>attaching virtual functions >>>of a SRIOV capable network card directly to a VM. >>>This patch adds the capability to configure such a device. >>> >>>Signed-off-by: Dirk Herrendoerfer<d.herrendoerfer at herrendoerfer.name> >>> >>>diff --git a/docs/schemas/domain.rng b/docs/schemas/domain.rng >>>index 7163c6e..e2a66ae 100644 >>>--- a/docs/schemas/domain.rng >>>+++ b/docs/schemas/domain.rng >>>@@ -2351,7 +2351,7 @@ >>> </define> >>> <define name="bridgeMode"> >>> <data type="string"> >>>-<param name="pattern">(vepa|bridge|private)</param> >>>+<param name="pattern">(vepa|bridge|private|passthru)</param> >>> </data> >>> </define> >>> <define name="addrMAC"> >>Missing corresponding documentation in docs/formatdomain.html.in to >>describe the new mode. >> >>What happens if you try to use this mode but you have an older kernel? >>Do we need to add any sanity checking to give a saner error message than >>just blindly trying the string and reporting back whatever message gets >>returned about an unknown argument? >> >>The rest of this patch looks okay to me (with my disclaimer that I've >>never used an SRIOV card), but I'd rather wait for a v2 than push this >>without documentation. >The kernel GIT commit actually has some useful info > > >commit eb06acdc85585f28864261f28659157848762ee4 >Author: Sridhar Samudrala&lt;sri(a)us.ibm.com&gt; >Date: Thu Oct 28 13:10:50 2010 +0000 > > macvlan: Introduce 'passthru' mode to takeover the underlying device > > With the current default 'vepa' mode, a KVM guest using virtio with > macvtap backend has the following limitations. > - cannot change/add a mac address on the guest virtio-net > - cannot create a vlan device on the guest virtio-net > - cannot enable promiscuous mode on guest virtio-net I had read that commit notice earlier, and didn't understand the first item - which MAC address needs to be changed? Doesn't the guest have its own MAC address, unrelated to the MAC address of the underlying device on the host?