From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Gatliff Subject: Re: UIO - interrupt performance Date: Tue, 21 Oct 2008 06:39:58 -0500 Message-ID: <48FDBF8E.3060700@billgatliff.com> 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> <48FDAEE1.9080503@grandegger.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <48FDAEE1.9080503@grandegger.com> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Wolfgang Grandegger Cc: Ben Nizette , Marco Stornelli , Alessio Igor Bogani , "Douglas, Jim (Jim)" , Embedded Linux mailing list Wolfgang Grandegger wrote: > Ben Nizette wrote: >> 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. > > I known, fortunately it's not that simple or even feasible. Image a > network driver with I/O multiplexing used by various processes. Actually, UIO is pretty useful for that when combined with tun/tap. > That's *not* an option, please read the GPL license conditions. At least > it's legal gray area. Note that it's not my intention to start a > discussion on that. Then I will only contradict you, and not cite my supporting evidence. :) b.g. -- Bill Gatliff bgat@billgatliff.com