From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sat, 13 Dec 2008 01:29:35 +0100 From: "Hans J. Koch" Subject: Re: [PATCH 1/1] Userspace I/O (UIO): Add support for userspace DMA Message-ID: <20081213002934.GB3084@local> References: <43FC624C55D8C746A914570B66D642610367F29B@cos-us-mb03.cos.agilent.com> <1228379942.5092.14.camel@twins> <20081204180809.GB3079@local> <1228461060.18899.8.camel@twins> <20081205094447.GA3081@local> <208aa0f00812051632h38fc0a5g58d233190436cc90@mail.gmail.com> <1229102712.13566.14.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1229102712.13566.14.camel@twins> Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Peter Zijlstra Cc: Edward Estabrook , "Hans J. Koch" , edward_estabrook@agilent.com, linux-kernel@vger.kernel.org, gregkh@suse.de, edward.estabrook@gmail.com, hugh , linux-mm , Thomas Gleixner List-ID: On Fri, Dec 12, 2008 at 06:25:12PM +0100, Peter Zijlstra wrote: > On Fri, 2008-12-05 at 16:32 -0800, Edward Estabrook wrote: > > > Well, UIO already rapes the mmap interface by using the "offset" parameter to > > > pass in the number of the mapping. > > > > Exactly. > > Had I known about it then, I'd NAK'd it, but I guess now that its > already merged changing it will be hard :/ It was in -mm for half a year before it went to mainline in 2.6.23, the documentation being present all the time. It was discussed intensively on lkml, and several core kernel developers reviewed it. The special use of the mmap() offset parameter was never even mentioned by anybody. I remember that so well because I actually expected critizism, but everybody was fine with it. And to be honest, even though it's unusual, I still find it a good solution. Thanks, Hans