From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936566AbXHHTre (ORCPT ); Wed, 8 Aug 2007 15:47:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758997AbXHHTrZ (ORCPT ); Wed, 8 Aug 2007 15:47:25 -0400 Received: from ns.suse.de ([195.135.220.2]:56210 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756674AbXHHTrY (ORCPT ); Wed, 8 Aug 2007 15:47:24 -0400 To: ebiederm@xmission.com (Eric W. Biederman) Cc: "Huang, Ying" , akpm@linux-foundation.org, Yinghai Lu , Randy Dunlap , Chandramouli Narayanan , linux-kernel@vger.kernel.org, "Mao, Bibo" Subject: Re: [PATCH 0/5] x86_64 EFI support -v3 References: <1185851569.23149.25.camel@caritas-dev.intel.com> <1186378838.3769.27.camel@caritas-dev.intel.com> From: Andi Kleen Date: 08 Aug 2007 22:41:43 +0200 In-Reply-To: Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ebiederm@xmission.com (Eric W. Biederman) writes: > > Since there are people actively investigating things like booting > OpenBSD via kexec things get even worse. Nothing hardly runs > on ia64 so that issue doesn't come up. If you want to do a popularity contest I expect there are far more ia64 linux users than kexec-of-openbsd users. > As for not using EFI at all. If we can avoid it/not use it in the > dump kernel there is very little point in having it in the primary > kernel. One interesting area is to use it for saving oops data. But that has to be simple. I'm not sure complicated context switches are a good idea here. However I agree it probably doesn't make sense to do virtual mode just for the clock services -- so far we seem to be fine just talking to the hardware directly. > So far there don't seem to be any compelling advantages to running > EFI in virtual address mode and several compelling disadvantages > included having to change the permissions on the kernels memory > map to running EFI in virtual mode. I don't think it's a big issue to have a few less NX bits. Just the original patch for it was ugly. > Please let's stick to a physical mode trampoline and only revisit > the topic when users start having problems because of the performance > hit of going through our trampoline to the EFI runtime services. So you want to switch to new page tables when calling EFI services after boot? Potential problems: - Interrupts have to be disabled. Is that ok? - When EFI BIOS start crashing how do we set up exception handlers for this? I guess it would get complex long term. Also doesn't really sound attractive. -Andi