From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751295AbVLPDTQ (ORCPT ); Thu, 15 Dec 2005 22:19:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751296AbVLPDTQ (ORCPT ); Thu, 15 Dec 2005 22:19:16 -0500 Received: from mail.kroah.org ([69.55.234.183]:44186 "EHLO perch.kroah.org") by vger.kernel.org with ESMTP id S1751295AbVLPDTQ (ORCPT ); Thu, 15 Dec 2005 22:19:16 -0500 Date: Thu, 15 Dec 2005 16:51:38 -0800 From: Greg KH To: Benjamin Herrenschmidt Cc: Linux Kernel list , linux-pci Subject: Re: MSI and driver APIs Message-ID: <20051216005138.GA20547@kroah.com> References: <1134617893.16880.17.camel@gaston> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1134617893.16880.17.camel@gaston> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 15, 2005 at 02:38:12PM +1100, Benjamin Herrenschmidt wrote: > So I want to start looking into separate implementation for powerpc, and > based on what I come up with, find the commonalities and split the > generic code. That would be great, as it really is i386/x86-64 specific right now. > However, there is at least one assumption that annoys me: > > Currently, we assume that MSIs are disabled upon discovery of a device. > That is, a driver probe() routine is called with MSIs off. > > This is annoying on platforms with "intelligent" firmwares like POWER > with hypervisor, as the firmware will have already configured MSIs for > the full system & assigned them to devices. If you are curious as to why this is, look at the lkml archives about a month or two ago, where I tried to enable MSI by default. It was a real mess and caused way more problems than it tried to solve. So, as David said, I don't think this is going to work out, sorry. thanks, greg k-h