Re: [Xen-devel] [PATCH] set mtu from bridge also on vif interface

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Sun, 2011-02-06 at 13:41 +0000, Olaf Hering wrote:
> Apply mtu size from bridge interface also in vif interface.
> This depends on a kernel change which allows arbitrary mtu sizes until
> the frontend driver has connected to the backend driver. Without this
> kernel change, the vif mtu size will be limited to 1500 even with this
> change to the vif-bridge script.
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

In my experience the bridge will only allow it's MTU to be set to the
minimum of all the ports (or 1500ish if there are no ports) and will
reset to the new minimum when you add a new port.

So does this patch do anything in the absence of the ability to
configure the MTU of a VIF from the toolstack?

Ian.

> 
> ---
>  tools/hotplug/Linux/vif-bridge |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> --- xen-unstable.hg-4.1.22870.orig/tools/hotplug/Linux/vif-bridge
> +++ xen-unstable.hg-4.1.22870/tools/hotplug/Linux/vif-bridge
> @@ -82,6 +82,11 @@ fi
>  case "$command" in
>      online)
>          setup_virtual_bridge_port "$dev"
> +        mtu="`ip link show $bridge | awk '/mtu/ { print $5 }'`"
> +        if [ -n "$mtu" ] && [ "$mtu" -gt 0 ]
> +        then
> +                ip link set $dev mtu $mtu || :
> +        fi
>          add_to_bridge "$bridge" "$dev"
>          ;;
>  
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel