Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756318AbYGMUaI (ORCPT ); Sun, 13 Jul 2008 16:30:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755110AbYGMU3z (ORCPT ); Sun, 13 Jul 2008 16:29:55 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:40074 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755090AbYGMU3y (ORCPT ); Sun, 13 Jul 2008 16:29:54 -0400 From: "Rafael J. Wysocki" To: Andi Kleen Subject: Re: [RFT] x86 acpi: normalize segment descriptor register on resume Date: Sun, 13 Jul 2008 22:32:00 +0200 User-Agent: KMail/1.9.6 (enterprise 20070904.708012) Cc: "H. Peter Anvin" , Andy Lutomirski , Matthew Garrett , Ingo Molnar , public-kernel-testers-u79uwXL29TY76Z2rM5mHXA@lo.gmane.org, ACPI Devel Maling List , LKML , pm list , Pavel Machek References: <200807010148.02135.rjw@sisk.pl> <487A62B3.8010207@zytor.com> <487A63D2.9040006@firstfloor.org> In-Reply-To: <487A63D2.9040006@firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200807132232.01489.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1652 Lines: 43 On Sunday, 13 of July 2008, Andi Kleen wrote: > H. Peter Anvin wrote: > > Andi Kleen wrote: > >> > >> Hmm, but the change was not supposed to break the s3 bios. Something > >> fishy is going on. It sounds like the s3 bios relies on some earlier > >> segment register setup. > >> > >> If true this means the segment register reset would need to be moved > >> later after S3 bios ran. Saving/restoring is unfortunately not possible > >> because we cannot save/restore the hidden state loaded from the GDT > >> earlier. > >> > > > > That really doesn't make sense, though. The VESA BIOS has to be entered > > in clean real mode; it's designed to be entered from reset, after all. > > There is definitely something fishy going on, but I don't think this > > particular aspect is it. > > It probably switches to protected mode. I noticed this on my old > Fujitsu laptop when I tried to make the S3 wakeup run in the s2ram x86 emulator > and found it entered protected mode at some point, which x86emu > didn't support. > > I guess Lenovo is doing the same. > > And that protected mode code relies on some GDT values that have been > loaded earlier when the BIOS also went into protected mode. > > It seems the BIOS programmers really don't like real mode anymore. > Somehow understandable. So should we check if we are in real mode at the entry point? That would compilcate things a lot. Thanks, Rafael -- 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/