From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030444Ab2CTQnq (ORCPT ); Tue, 20 Mar 2012 12:43:46 -0400 Received: from terminus.zytor.com ([198.137.202.10]:47874 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754271Ab2CTQnp (ORCPT ); Tue, 20 Mar 2012 12:43:45 -0400 Message-ID: <4F68B3A6.4080404@zytor.com> Date: Tue, 20 Mar 2012 09:43:18 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120209 Thunderbird/10.0.1 MIME-Version: 1.0 To: Maarten Lankhorst CC: Matt Fleming , Alan Cox , Shea Levy , linux-kernel@vger.kernel.org Subject: Re: EFI Boot Stub Early Console References: <4F5E46EA.7020602@shealevy.com> <4F5E47E4.2070303@shealevy.com> <4F5E74A0.60001@zytor.com> <4F5E761B.7010608@shealevy.com> <4F5E775D.7080702@zytor.com> <4F648DD3.3000405@shealevy.com> <1332069701.4041.42.camel@mfleming-mobl1.ger.corp.intel.com> <4F65D09B.4050807@shealevy.com> <1332146834.4041.46.camel@mfleming-mobl1.ger.corp.intel.com> <20120319155639.7cff5df6@pyx> <1332172989.4041.52.camel@mfleming-mobl1.ger.corp.intel.com> <4F68A60D.2020303@gmail.com> In-Reply-To: <4F68A60D.2020303@gmail.com> X-Enigmail-Version: 1.3.5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/20/2012 08:45 AM, Maarten Lankhorst wrote: > Hey Matt, > > Op 19-03-12 17:03, Matt Fleming schreef: >> On Mon, 2012-03-19 at 15:56 +0000, Alan Cox wrote: >>>>> any bootloader (including the bootstub) will call ExitBootServices() >>>>> before any printk'ing actually happens?? Or am I misunderstanding the >>>>> spec somehow? I suppose I could just try it and see what happens... >>>> Oops. Good point, that isn't going to work. >>> Surely it works fine if you are using bootstub directly from EFI ? >> Yeah, up until the point you call ExitBootServices(), which is very >> early in the boot process. After that you can't rely on the validity of >> the console pointers in the system table. >> > I think my system spontaneously rebooted when I tried to > do some output right after ExitBootServices when debugging > the efi stub, so not only is this unreliable, it will fail to boot for > at least some systems out there. > I would expect it to fail for just about any system. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.