Stuart Henderson [[email protected]] wrote:
> On 2014/08/21 08:45, Chris Cappuccio wrote:
> > Stuart Henderson [[email protected]] wrote:
> > > On 2014/08/20 17:17, Chris Cappuccio wrote:
> > > > David Gwynne [[email protected]] wrote:
> > > > > sthen@ says this is likely a bit optimistic. while most of our 
> > > > > drivers unconditionally configure their max mru, there's some stupid 
> > > > > ones that still interpret the configured mtu as a what the mru should 
> > > > > be.
> > > > > 
> > > > 
> > > > All the more reason to make this change, I'd say :)
> > > 
> > > it's not just that - there are some like et(4) with obvious trade-offs 
> > > visible
> > > in the driver source code which are only wanted in the case where jumbos 
> > > are
> > > actually in use. and who knows what various chips will do internally when 
> > > the
> > > command to permit jumbos or raise the valid packet size is sent.
> > > 
> > 
> > I don't think this is relevant. If a chip or driver is buggy in the jumbo 
> > MTU
> > non-vlan case, now it will be buggy in the (somewhat unique) vlan jumbo MTU
> > case as well....
> 
> Oh I was thinking of the case where we changed those drivers to fix things
> so that the "1500 MTU untagged / high MTU tagged" state worked which would
> involve downsides for non-jumbo. If you don't care if the new support
> actually works on some chips then that wouldn't apply..
> 

Well in the case of if_et, the change the dlg proposes in if_vlan would not
make a difference to the if_et behavior at all. My first glance at et says
hardmtu == mtu 

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