Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261605AbVCNAge (ORCPT ); Sun, 13 Mar 2005 19:36:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261608AbVCNAge (ORCPT ); Sun, 13 Mar 2005 19:36:34 -0500 Received: from mail17.syd.optusnet.com.au ([211.29.132.198]:12466 "EHLO mail17.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S261605AbVCNAg1 (ORCPT ); Sun, 13 Mar 2005 19:36:27 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16948.56475.116221.135256@wombat.chubb.wattle.id.au> Date: Mon, 14 Mar 2005 11:36:43 +1100 From: Peter Chubb To: Jon Smirl Subject: Re: User mode drivers: part 1, interrupt handling (patch for 2.6.11) In-Reply-To: <9e473391050312075548fb0f29@mail.gmail.com> References: <16945.4650.250558.707666@berry.gelato.unsw.EDU.AU> <9e473391050312075548fb0f29@mail.gmail.com> X-Mailer: VM 7.17 under 21.4 (patch 15) "Security Through Obscurity" XEmacs Lucid Comments: Hyperbole mail buttons accepted, v04.18. X-Face: GgFg(Z>fx((4\32hvXq<)|jndSniCH~~$D)Ka:P@e@JR1P%Vr}EwUdfwf-4j\rUs#JR{'h# !]])6%Jh~b$VA|ALhnpPiHu[-x~@<"@Iv&|%R)Fq[[,(&Z'O)Q)xCqe1\M[F8#9l8~}#u$S$Rm`S9% \'T@`:&8>Sb*c5d'=eDYI&GF`+t[LfDH="MP5rwOO]w>ALi7'=QJHz&y&C&TE_3j! Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1494 Lines: 31 >>>>> "Jon" == Jon Smirl writes: Jon> On Fri, 11 Mar 2005 14:36:10 +1100, Peter Chubb Jon> wrote: >> As many of you will be aware, we've been working on infrastructure >> for user-mode PCI and other drivers. The first step is to be able >> to handle interrupts from user space. Subsequent patches add >> infrastructure for setting up DMA for PCI devices. Jon> I've tried implementing this before and could not get around the Jon> interrupt problem. Most interrupts on the x86 architecture are Jon> shared. Disabling the IRQ at the PIC blocks all of the shared Fortunately, most interrupts on IA64, ARM, etc., are unshared. And with PCI-Express, the problem will go away. Even on X86, things aren't all bad: one can usually find a PCI slot which doesn't share interrupts with anything you care about. The scenario I'm thinking about with these patches are things like low-latency user-level networking between nodes in a cluster, where for good performance even with a kernel driver you don't want to share your interrupt line with anything else. -- Dr Peter Chubb http://www.gelato.unsw.edu.au peterc AT gelato.unsw.edu.au The technical we do immediately, the political takes *forever* - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/