From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco Stornelli Subject: Re: UIO - interrupt performance Date: Tue, 21 Oct 2008 12:24:41 +0200 Message-ID: <48FDADE9.3080107@coritel.it> References: <5958B8D7916AB84781FE0E7B57C218CB75AB98@306900ANEX2.global.avaya.com> <48FC71BD.9070703@coritel.it> <48FCAE16.70509@billgatliff.com> <48FD94AA.8070900@coritel.it> <63a49ef40810210201x36249476tcc75141d87a610f2@mail.gmail.com> <48FDA13F.3030303@coritel.it> <1224581853.3954.127.camel@moss.renham> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1224581853.3954.127.camel@moss.renham> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Ben Nizette Cc: Alessio Igor Bogani , Bill Gatliff , "Douglas, Jim (Jim)" , Embedded Linux mailing list No I don't think you can decide kernel or user space, indeed you can read my previous posts, I quite agree with you, I meant the same to Bill Gatliff. Ben Nizette ha scritto: > On Tue, 2008-10-21 at 11:30 +0200, Marco Stornelli wrote: >> I could agree, but "the facto" due to UIO license condition, a company >> often uses UIO drivers, regardless performance, debug, etc, only as not >> to public the code under GPL. > > It sounds to me like you think that driver authors can sit down and > decide whether they want to implement their driver in userspace or > kernel space. For 99% of drivers that's simply not true. You *cannot* > write userspace drivers for most hardware, the hooks just aren't > available. UIO is Userspace I/O, not a set of general hooks for > userspace drivers. > > If people want drivers not under the GPL then they can distribute a > binary-only module (though thank $DEITY there aren't many of those > left). Userspace I/O exists to provide good performance interfacing to > a family of devices - those which exist just to shuffle data around and > have an interrupt to tell you when they're done. > > Do you have any example of a userspace i/o driver which exists to get > around licencing constraints? > > --Ben. > > -- Marco Stornelli Embedded Software Engineer CoRiTeL - Consorzio di Ricerca sulle Telecomunicazioni http://www.coritel.it marco.stornelli@coritel.it +39 06 72582838