From mboxrd@z Thu Jan 1 00:00:00 1970 From: Len Brown Subject: Re: Any difference between disabling ACPI in BIOS and acpi=off Date: Tue, 6 Mar 2007 01:01:56 -0500 Message-ID: <200703060101.56599.lenb@kernel.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:34670 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965795AbXCFGDP (ORCPT ); Tue, 6 Mar 2007 01:03:15 -0500 In-Reply-To: Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Zhao Forrest Cc: linux-acpi@vger.kernel.org On Tuesday 06 March 2007 00:56, Zhao Forrest wrote: > Hi, > > For RHEL4-U4-64bit, we can boot up kernel with ACPI enabled in BIOS > whether we add the kernel parameter "acpi=off" or not; however kernel > can't boot with ACPI disabled in BIOS whether we add kernel parameter > "acpi=off" or not. > > My question is, is there any difference between disabling ACPI in BIOS > and acpi=off from the kernel's point of view? There shouldn't be. However, it may be that the BIOS is doing something stupid when disabling ACPI, such as mucking up e820 -- which is technically part of ACPI, but Linux uses it in both ACPI and legacy mode. if you have the "debug" console log from the failed boot, that may give a clue. -Len