From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754538Ab2CXEna (ORCPT ); Sat, 24 Mar 2012 00:43:30 -0400 Received: from terminus.zytor.com ([198.137.202.10]:59654 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751844Ab2CXEn3 (ORCPT ); Sat, 24 Mar 2012 00:43:29 -0400 Message-ID: <4F6D50DD.4050306@zytor.com> Date: Fri, 23 Mar 2012 21:43:09 -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: Thomas Renninger CC: eric.piel@tremplin-utc.net, vojcek@tlen.pl, dsdt@gaugusch.at, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, Lin Ming , lenb@kernel.org, robert.moore@intel.com, Al Viro Subject: Re: [PATCH] ACPI: Implement overriding of arbitrary ACPI tables via initrd References: <1332512984-79664-1-git-send-email-trenn@suse.de> <201203240242.07724.trenn@suse.de> <4F6D2AF8.3070707@zytor.com> <201203240402.38749.trenn@suse.de> In-Reply-To: <201203240402.38749.trenn@suse.de> X-Enigmail-Version: 1.4 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 03/23/2012 08:02 PM, Thomas Renninger wrote: >> >> Sorry, it doesn't work that way. > I guess this would not be the first time a good feature has been added, > knowing that a more general API will be build around it later. > 10 lines are really easy to adopt. > No, what you want is to add a new interface, which is going to have to be maintained indefinitely. That's the problem. >> I see two realistic options: >> >> 1. We use cpio encapsulation for everything, with a special namespace >> for items used directly by the kernel, e.g. "kernel/". >> >> + Simple, existing tools can pick apart >> - May lead people to believe that the early-initrd portion can be >> compressed like the "normal" initrd portion, leading to strange >> problems. > Can this be implemented without using dynamic memory allocations? > If not, it's not suitable for early APCI overriding. Yes it can, as long as it is uncompressed. It just becomes a matter of walking the cpio headers which is effectively a linked list. It is more code than the simple header option, though. By the way, if "relying on the bootloader" was an option in any way then we would already have a solution in the form of the kernel data linked list. Unfortunately to the best of my knowledge not a single bootloader provides support for it. -hpa