Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753886Ab0ADTPx (ORCPT ); Mon, 4 Jan 2010 14:15:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753728Ab0ADTPx (ORCPT ); Mon, 4 Jan 2010 14:15:53 -0500 Received: from terminus.zytor.com ([198.137.202.10]:56316 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753628Ab0ADTPw (ORCPT ); Mon, 4 Jan 2010 14:15:52 -0500 Message-ID: <4B423E24.90106@zytor.com> Date: Mon, 04 Jan 2010 11:14:44 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Thunderbird/3.0 MIME-Version: 1.0 To: "Eric W. Biederman" CC: Yinghai Lu , Jesse Brandeburg , Ingo Molnar , Thomas Gleixner , "linux-kernel@vger.kernel.org" , Andrew Morton , NetDEV list , Jesse Brandeburg Subject: Re: Subject: [PATCH 1/2] x86: get back 15 vectors References: <4B347AEE.6030705@kernel.org> <20091228094707.GH24690@elte.hu> <4B398ECD.1080506@kernel.org> <4807377b1001031906s6b1ee576jc021da2642bb4147@mail.gmail.com> <4B415E73.1050801@kernel.org> <4B419113.1090204@kernel.org> <4B42362F.7040302@kernel.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1179 Lines: 29 On 01/04/2010 11:04 AM, Eric W. Biederman wrote: >> >> any reason that we can not use 0x40? > > Not that I now of. Reading the comment it looks like it was only > skipped so that the initial assignment of vectors would be. > > 0x31, 0x41, 0x51, 0x61, 0x71, 0x81, 0x91, 0xa1, 0xb1, 0xc1, 0xd1, 0xe1 > Instead of. > 0x30, 0x40, 0x50, 0x60, 0x70, 0x90, 0xa0, 0xb0, 0xc0, 0xc0, 0xe0 > > Which doesn't seem to be the worst notion, but at the point we are looking > for every vector we can get it does seem to be problematic. > This can presumably be worked around by tweaking the initial assignment algorithm slightly, without losing a whole vector to that. Also, if we abuse vector 0x1f as the IRQ reassignment vector, we free up a full 16 vectors per CPU -- this seems worthwhile especially since it is a decision that can be trivially undone in the future: this is all kernel internal, we're not creating any kind of API. -hpa -- 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/