From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030318AbWGKH3i (ORCPT ); Tue, 11 Jul 2006 03:29:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965250AbWGKH3i (ORCPT ); Tue, 11 Jul 2006 03:29:38 -0400 Received: from mail-in-03.arcor-online.net ([151.189.21.43]:64418 "EHLO mail-in-03.arcor-online.net") by vger.kernel.org with ESMTP id S965237AbWGKH3h (ORCPT ); Tue, 11 Jul 2006 03:29:37 -0400 In-Reply-To: References: <1152571162.1576.122.camel@localhost.localdomain> <1152595205.6346.26.camel@localhost.localdomain> Mime-Version: 1.0 (Apple Message framework v750) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <9ABD3384-5829-4365-988C-43310D374CE5@kernel.crashing.org> Cc: Benjamin Herrenschmidt , Andrew Morton , Dave Olson , linux-kernel@vger.kernel.org Content-Transfer-Encoding: 7bit From: Segher Boessenkool Subject: Re: [PATCH 2/2] Initial generic hypertransport interrupt support. Date: Tue, 11 Jul 2006 09:29:29 +0200 To: ebiederm@xmission.com (Eric W. Biederman) X-Mailer: Apple Mail (2.750) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > As for supporting multiple irqs in plain MSI mode, I don't think > we want to do that. The problem is that multiple interrupts > in msi mode cannot be individually routed. On some(/many/most) platforms that isn't a problem. Platforms for which it is can just refuse to allocate more than one MSI at once. > I think we really want > to encourage vendors who are building cards with multiple MSI irqs > to use MSI-X. MSI-X has a lot fewer ugly special cases and all > architectures can individually route the irqs. We still should support whatever hardware already exists, if possible. > If there are interesting cards that support just MSI mode and really > need more than one irq I would be happy to reconsider that decision > but my impression was that plain MSI was basically not quite flexible > enough to really be interesting, and supporting just one MSI irq was > ok but any more would lead to all kinds of strange special cases. Individual drivers can deal with those special cases if they are device- specific; and the platform can just refuse to do more than one MSI if something platform-specific would prevent correct operation. It would be nice to have the MSI and MSI-X interfaces have the same calling convention; in fact, they can probably be folded into one. Segher