Changing MTU on cxgbe

[K. Macy]

On Thursday, May 26, 2016, Navdeep Parhar <nparhar at gmail.com> wrote:

> On Fri, May 27, 2016 at 12:57:34AM -0400, Garrett Wollman wrote:
> > In article <
> CAJpsHY4vF5Ky6GuAusLOOROgiQuyD2CcRmVxu8x3cArQRZxcbg at mail.gmail.com
> <javascript:;>> you write:
> >
> > ># ifconfig -m cxgbe0
> > >cxgbe0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST>
> >
> > ># ifconfig cxgbe0 mtu 9000
> > >ifconfig: ioctl SIOCSIFMTU (set mtu): Invalid argument
> >
> > I believe this device, like many others, does not allow the MTU (or
> > actually the MRU) to be changed once the receive ring has been set up
>
> This is not correct.  You can change the MTU of a cxgbe/cxl interface at
> any time (whether it's up or down, passing traffic or idle, etc.).


For some reason the stack needs init to be called when the MTU is changed
for it to actually change the size of the packets passed to the driver. At
least cxgb does not do that. I'm not at my computer right now, but cxgbe
may be the same. If that's the case just up / down the interface. It _will_
take effect without that if it's passed at module load.


>
> Regards,ll
> Navdeep
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