From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757816Ab0HCV6P (ORCPT ); Tue, 3 Aug 2010 17:58:15 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:39694 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757597Ab0HCV6O (ORCPT ); Tue, 3 Aug 2010 17:58:14 -0400 To: Matthew Garrett Cc: Huang Ying , "Tang\, Feng" , Bjorn Helgaas , "linux-kernel\@vger.kernel.org" Subject: Re: EFI runtime-services on x86_64 References: <201007301458.50263.bjorn.helgaas@hp.com> <20100802103535.6442ab49@feng-i7> <1280716920.2771.1519.camel@yhuang-dev> <20100803215346.GA4476@srcf.ucam.org> From: ebiederm@xmission.com (Eric W. Biederman) Date: Tue, 03 Aug 2010 14:58:10 -0700 In-Reply-To: <20100803215346.GA4476@srcf.ucam.org> (Matthew Garrett's message of "Tue\, 3 Aug 2010 22\:53\:46 +0100") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=67.188.4.80;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 67.188.4.80 X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Scanned: No (on in01.mta.xmission.com); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Matthew Garrett writes: > On Tue, Aug 03, 2010 at 02:45:33PM -0700, Eric W. Biederman wrote: > >> EFI runtime calls have the nasty fact that they don't work in general even >> if EFI is present because you may have the wrong word size EFI running on >> your machine. A 32bit EFI and a 64bit kernel or a 64bit EFI and a 32bit kernel. > > You've already failed to boot in that case. Only if you have EFI runtime services enabled in your kernel. You can skip the efi junk and the kernel runs just fine. Doing what we do on every other platform which appears to be a combination of ACPI and direct hardware access appears to be good enough, and that is a path that actually gets tested regularly. Eric