Date: Fri, 27 May 2016 00:38:07 -0700 From: "K. Macy" <kmacy@freebsd.org> To: "K. Macy" <kmacy@freebsd.org>, Garrett Wollman <wollman@hergotha.csail.mit.edu>, "dmarquess@gmail.com" <dmarquess@gmail.com>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: Changing MTU on cxgbe Message-ID: <CAHM0Q_NsVP=nzB6gUeB4qZAf4uVNR-_pNw=Oou3G2mPT99-bYA@mail.gmail.com> In-Reply-To: <20160527072951.GC10148@ox> References: <CAJpsHY4vF5Ky6GuAusLOOROgiQuyD2CcRmVxu8x3cArQRZxcbg@mail.gmail.com> <201605270457.u4R4vYqu018911@hergotha.csail.mit.edu> <20160527063731.GB10148@ox> <CAHM0Q_P-BJXZf4pXqTpqUx4x4C7ZBTWXOeBxR=7r1BqzhXgU2w@mail.gmail.com> <20160527072951.GC10148@ox>
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On Friday, May 27, 2016, Navdeep Parhar <nparhar@gmail.com> wrote: > On Fri, May 27, 2016 at 12:23:02AM -0700, K. Macy wrote: > > On Thursday, May 26, 2016, Navdeep Parhar <nparhar@gmail.com > <javascript:;>> wrote: > > > > > On Fri, May 27, 2016 at 12:57:34AM -0400, Garrett Wollman wrote: > > > > In article < > > > CAJpsHY4vF5Ky6GuAusLOOROgiQuyD2CcRmVxu8x3cArQRZxcbg@mail.gmail.com > <javascript:;> > > > <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. Sorry. Continue on. -M > > The problem that was reported was that the ioctl that sets the MTU > failed, not that the ioctl succeeded but the MTU change did not take > effect. > Regards, > Navdeep >
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