From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: [PATCH 1/2] igb: Implement reading of reg RQDPC (Receive Queue Drop Packet Count) Date: Thu, 14 May 2009 10:03:08 +0200 Message-ID: <1242288188.18487.127.camel@localhost.localdomain> References: <1241703346.18487.22.camel@localhost.localdomain> <1241703431.18487.25.camel@localhost.localdomain> <1242035422.18487.78.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "e1000-devel@lists.sourceforge.net" , "netdev@vger.kernel.org" , "Waskiewicz Jr, Peter P" , "Ronciak, John" , "Kirsher, Jeffrey T" , "David S. Miller" To: "Williams, Mitch A" Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: e1000-devel-bounces@lists.sourceforge.net List-Id: netdev.vger.kernel.org On Wed, 2009-05-13 at 15:07 -0600, Williams, Mitch A wrote: > > >-----Original Message----- > >From: Jesper Dangaard Brouer [mailto:hawk@comx.dk] > >Sent: Monday, May 11, 2009 2:50 AM > > > >I have now tested it on a 82575 chip NIC. (I just got my 82575 NIC > >working again (This 12 port monster from Hotlava Systems, just needed > >more power on PCIe 100Watt)). > > > >I don't see the reason for doing special checks for the 82575. Reading > >the RQDPC registers on 82575 always returns 0. I don't see any harm in > >that!? (it also returns zero in overload situations) > > > >What do you want to redraw your NAK? > > > > Jesper, I still stand by my NAK. It's never ever a good idea to read > non-existent hardware registers. You don't know what effect those > reads will have on the hardware. These addresses may be aliased to other > registers without being documented. Hardware designers do this all the > time to save a few gates in the address decode logic, and these aliases > may or may not be documented. If this is the case, reading these > registers will have unintended consequences. You might be clearing some > other statistic, or worse. > > Since we just don't know, it's better to be safe than sorry. Wrap > those register reads so they only happen on 82576, and I'll happily > ack your patch. Fine, you argumented well for your case. I'll repost some patches when time permits... -- Med venlig hilsen / Best regards Jesper Brouer ComX Networks A/S Linux Network developer Cand. Scient Datalog / MSc. Author of http://adsl-optimizer.dk LinkedIn: http://www.linkedin.com/in/brouer ------------------------------------------------------------------------------ The NEW KODAK i700 Series Scanners deliver under ANY circumstances! Your production scanning environment may not be a perfect world - but thanks to Kodak, there's a perfect scanner to get the job done! With the NEW KODAK i700 Series Scanner you'll get full speed at 300 dpi even with all image processing features enabled. http://p.sf.net/sfu/kodak-com