From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264321AbTLIJvK (ORCPT ); Tue, 9 Dec 2003 04:51:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264394AbTLIJvJ (ORCPT ); Tue, 9 Dec 2003 04:51:09 -0500 Received: from 216-239-45-4.google.com ([216.239.45.4]:33407 "EHLO 216-239-45-4.google.com") by vger.kernel.org with ESMTP id S264382AbTLIJuk (ORCPT ); Tue, 9 Dec 2003 04:50:40 -0500 Message-ID: <3FD59AD8.1060507@google.com> Date: Tue, 09 Dec 2003 01:50:16 -0800 From: Paul Menage User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030701 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Arjan van de Ven CC: agrover@groveronline.com, linux-kernel@vger.kernel.org, acpi-devel@lists.sourceforge.net Subject: Re: ACPI global lock macros References: <3FD59441.2000202@google.com> <1070962573.5223.2.camel@laptop.fenrus.com> <3FD5990A.9020908@google.com> <20031209094356.GA19702@devserv.devel.redhat.com> In-Reply-To: <20031209094356.GA19702@devserv.devel.redhat.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Arjan van de Ven wrote: >>>maybe the odd thing is that it exists at all? >>>(eg why does ACPI need to have it's own locking primitives...) >> >>Because the ACPI spec defines its own locking protocol for >>synchronization between the OS and the BIOS. > > > ... which can't be written based on linux locks ? I assume (hope!) there's already a higher-level linux lock serializing access to acpi_acquire_global_lock() although I've not delved deeply into the code. This is the lock described on p112 of http://www.acpi.info/DOWNLOADS/ACPIspec-2-0c.pdf, which has the semantics that if the OS wants to take the lock while the BIOS holds it, it sets a bit and waits for an interrupt from the BIOS. I don't see that it could be naturally implemented using a linux lock. Paul