From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262312AbTELQkw (ORCPT ); Mon, 12 May 2003 12:40:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262316AbTELQkw (ORCPT ); Mon, 12 May 2003 12:40:52 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:38297 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S262312AbTELQku (ORCPT ); Mon, 12 May 2003 12:40:50 -0400 Date: Mon, 12 May 2003 17:53:31 +0100 From: Matthew Wilcox To: Jeff Garzik Cc: linux-kernel@vger.kernel.org, Ivan Kokshaysky , willy@debian.org, davem@redhat.com Subject: Re: Message Signalled Interrupt support? Message-ID: <20030512165331.GZ29534@parcelfarce.linux.theplanet.co.uk> References: <20030512163249.GF27111@gtf.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030512163249.GF27111@gtf.org> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 12, 2003 at 12:32:49PM -0400, Jeff Garzik wrote: > Has anybody done any work, or put any thought, into MSI support? Work -- no. Thought? A little. Seems to me that MSIs need to be treated as a third form of interrupts (level/edge/message). The address that the MSI will write to is clearly architecture dependent (may even be irq-controller-dependent, depending on your architecture). request_irq() is an insufficient function to deal with this -- request_msi() may be needed instead. It'll need to return an address to pass to the card. (We need a mechanism to decide whether it's a 32-bit or 64-bit address). Oh, and don't make this too PCI-specific -- native PARISC interrupts are MSI and you can see how handled it in arch/parisc/kernel/irq.c. > Would things massively break if I set up MSI manually in the driver? Might do, might not. -- "It's not Hollywood. War is real, war is primarily not about defeat or victory, it is about death. I've seen thousands and thousands of dead bodies. Do you think I want to have an academic debate on this subject?" -- Robert Fisk