From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751784AbaJOV5H (ORCPT ); Wed, 15 Oct 2014 17:57:07 -0400 Received: from mail-pd0-f169.google.com ([209.85.192.169]:49874 "EHLO mail-pd0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751059AbaJOV5F (ORCPT ); Wed, 15 Oct 2014 17:57:05 -0400 Date: Wed, 15 Oct 2014 14:57:01 -0700 From: Benjamin Poirier To: =?iso-8859-1?Q?Llu=EDs?= Batlle i Rossell Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Carles =?iso-8859-1?Q?Pag=E8s?= , linux-arm-kernel@lists.infradead.org Subject: Re: Regarding tx-nocache-copy in the Sheevaplug Message-ID: <20141015215701.GA4109@f1.synalogic.ca> References: <20141013105246.GD1972@vicerveza.homeunix.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20141013105246.GD1972@vicerveza.homeunix.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/10/13 12:52, Lluís Batlle i Rossell wrote: > Hello, > > on the 7th of January 2014 ths patch was applied: > https://lkml.org/lkml/2014/1/7/307 > > [PATCH v2] net: Do not enable tx-nocache-copy by default > > In the Sheevaplug (ARM Feroceon 88FR131 from Marvell) this made packets to be > sent corrupted. I think this machine has something special about the cache. > > Enabling back this tx-nocache-copy (as it used to be before the patch) the > transfers work fine again. I think that most people, encountering this problem, > completely disable the tx offload instead of enabling back this setting. > > Is this an ARM kernel problem regarding this platform? This is odd, only x86 defines ARCH_HAS_NOCACHE_UACCESS. On arm, skb_do_copy_data_nocache() should end up using __copy_from_user() regardless of tx-nocache-copy.