From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758310Ab1LNWor (ORCPT ); Wed, 14 Dec 2011 17:44:47 -0500 Received: from terminus.zytor.com ([198.137.202.10]:34518 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758231Ab1LNWop (ORCPT ); Wed, 14 Dec 2011 17:44:45 -0500 Message-ID: <4EE926D2.3030803@zytor.com> Date: Wed, 14 Dec 2011 14:44:34 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111115 Thunderbird/8.0 MIME-Version: 1.0 To: Matthew Garrett CC: Mike Waychison , linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 3/4] EFI: Add support for variables longer than 1024 bytes References: <1323896791-10858-1-git-send-email-mjg@redhat.com> <1323896791-10858-4-git-send-email-mjg@redhat.com> <20111214223950.GA29264@srcf.ucam.org> In-Reply-To: <20111214223950.GA29264@srcf.ucam.org> X-Enigmail-Version: 1.3.4 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 12/14/2011 02:39 PM, Matthew Garrett wrote: > >> We need to be careful here. The store_raw ABI is broken, in the sense >> that the ABI from compat mode differs from that in 32bit mode (there >> is a long in the efi_variable structure which changes the offsets). I >> don't know how to fix it properly and still maintain proper ABI >> compatibility. > > True. > >> What are your thoughts on _not_ wrapping efi_variable with >> extended_efi_variable, and instead just using a >> "internal_efi_variable" structure that we copy stuff into/outof. I >> think that would make the memory management for dealing with the >> different sizes a lot easier to follow. > > Hm. I think that'd only work if we expose a new interface. Writes would > be easy enough to handle, but reads still need to work for old apps. > Would making the old ABI readonly and add a new write interface resolve the problem with compat mode? -hpa