From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 28 Jan 2001 12:23:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 28 Jan 2001 12:23:44 -0500 Received: from pcep-jamie.cern.ch ([137.138.38.126]:61189 "EHLO pcep-jamie.cern.ch") by vger.kernel.org with ESMTP id ; Sun, 28 Jan 2001 12:23:34 -0500 Date: Sun, 28 Jan 2001 18:22:15 +0100 From: Jamie Lokier To: "H. Peter Anvin" Cc: Rogier Wolff , "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: Linux Post codes during runtime, possibly OT Message-ID: <20010128182215.D9106@pcep-jamie.cern.ch> In-Reply-To: <200101281012.LAA04278@cave.bitwizard.nl> <3A73F1EB.B6F69A93@transmeta.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <3A73F1EB.B6F69A93@transmeta.com>; from hpa@transmeta.com on Sun, Jan 28, 2001 at 02:18:19AM -0800 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org H. Peter Anvin wrote: > It is; you'd have to specify "eax" as a clobber value, and that is > undesirable. For outb_p, EAX is used, usually for the last time, in the preceding "out" instruction so clobbering it is not a big deal. For inb_p, you first have to copy EAX to another register before outputting the post_byte. That's a small penalty. Are in[bwl]_p used anywhere time critical? (Richard Johnson's explanation for outb_p implies that inb_p is not required, but perhaps that explanation doesn't tell the whole story). > And you're still overwriting the POST value written by the BIOS. Can the BIOS-written value be read from port 0x80? -- Jamie - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/