Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933038AbWKMTfY (ORCPT ); Mon, 13 Nov 2006 14:35:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933039AbWKMTfX (ORCPT ); Mon, 13 Nov 2006 14:35:23 -0500 Received: from e36.co.us.ibm.com ([32.97.110.154]:35821 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S933038AbWKMTfW (ORCPT ); Mon, 13 Nov 2006 14:35:22 -0500 Date: Mon, 13 Nov 2006 14:34:47 -0500 From: Vivek Goyal To: "Eric W. Biederman" Cc: Andi Kleen , linux kernel mailing list , Reloc Kernel List , akpm@osdl.org, hpa@zytor.com, magnus.damm@gmail.com, lwang@redhat.com, dzickus@redhat.com, pavel@suse.cz, "Rafael J. Wysocki" Subject: Re: [RFC] [PATCH 10/16] x86_64: 64bit PIC ACPI wakeup Message-ID: <20061113193447.GB13832@in.ibm.com> Reply-To: vgoyal@in.ibm.com References: <20061113162135.GA17429@in.ibm.com> <200611131822.44034.ak@suse.de> <20061113175947.GA13832@in.ibm.com> <200611131913.32073.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1404 Lines: 35 On Mon, Nov 13, 2006 at 12:21:05PM -0700, Eric W. Biederman wrote: > Andi Kleen writes: > > >> This code (verify_cpu) is called while we are still in real mode. So it has > >> to be present in low 1MB. Now in trampoline has been designed to switch to > >> 64bit mode and then jump to the kernel hence kernel can be loaded anywhere > >> even beyond (4G). So if we move this code into say arch/x86_64/kernel/head.S > >> then we can't even call it. > > > > I didn't mean to call it. Just #include it from a common file > > I believe the duplication winds up happening in setup.S > Yes. So boot cpu code in setup.S is also doing these checks. So one of the options is that I create a new file says verify_cpu.S and this code can be shared by setup.S, trampoline.S and wakeup.S. Or, I can simply drop the verify_cpu bit from trampoline.S and wakeup.S. This looks like a non-essential bit and in the past we did not perform these checks in trampoline.S and wakeup.S At this point of time, I will prefer to go with second option of dropping extended checks in trampoline.S and wakeup.S to keep things simple. Does that make sense? Thanks Vivek - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/