Via Velocity minimum MTU size

[Jay Cliburn]

On Mon, 2006-05-22 at 08:46 -0400, Dave Jones wrote:
> On Mon, May 22, 2006 at 10:06:22AM +0100, Matt Davey wrote:
>  > On Sun, 2006-05-21 at 21:57 -0500, Jay Cliburn wrote:
>  > > On Sun, 2006-05-21 at 15:48 -0400, Dave Jones wrote:
>  > > >  > Can someone explain why the driver might constrain the NIC to a minimum
>  > > >  > MTU size of 1500?
>  > > > 
>  > > > Asking the developers on netdev at vger.kernel.org is going to get
>  > > > you the answer faster than asking here.
>  > 
>  > There is a patch:
>  > http://bugme.osdl.org/show_bug.cgi?id=4001
> 
> I think this may be a separate issue.
> 
> That last comment on 2006-03-01 mentions that it was included in mainline.
> The patch referenced in the other bug (http://bugzilla.kernel.org/show_bug.cgi?id=4380)
> does seem to be included in the kernel Jay was running (I just doublechecked
> the Fedora sources for that version).

There appear to be two issues in the referenced bug:

(1) VELOCITY_MIN_MTU is hardcoded at 1500 bytes in via-velocity.h, and
(2) An earlier version of the via-velocity driver couldn't handle
on-the-fly MTU changes.

Number (2) was resolved with a patch.  Number (1) was not.  I intend to
submit a patch to kernel.org, but first, can someone confirm that the
proper way to alter MTU size is:

ifconfig <interface> mtu <size>
service network restart

I can't get it to work unless I bounce the network service after making
the MTU change.  I just need to know if that's normal.

Thanks,
Jay