From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932222AbWESEPq (ORCPT ); Fri, 19 May 2006 00:15:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932224AbWESEPq (ORCPT ); Fri, 19 May 2006 00:15:46 -0400 Received: from ozlabs.org ([203.10.76.45]:29330 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S932222AbWESEPq (ORCPT ); Fri, 19 May 2006 00:15:46 -0400 Subject: Re: [RFC/PATCH] Make printk work for really early debugging From: Michael Ellerman Reply-To: michael@ellerman.id.au To: Andi Kleen Cc: linux-kernel@vger.kernel.org, Benjamin Herrenschmidt In-Reply-To: <200605181800.21829.ak@suse.de> References: <20060518091410.CC527679F4@ozlabs.org> <1147966886.8469.4.camel@localhost.localdomain> <200605181800.21829.ak@suse.de> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-ArSm8HUt+1BXJWalsCtU" Date: Fri, 19 May 2006 14:15:33 +1000 Message-Id: <1148012134.8515.10.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --=-ArSm8HUt+1BXJWalsCtU Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, 2006-05-18 at 18:00 +0200, Andi Kleen wrote: > On Thursday 18 May 2006 17:41, Michael Ellerman wrote: > > On Thu, 2006-05-18 at 15:55 +0200, Andi Kleen wrote: > > > Michael Ellerman writes: > > >=20 > > > > Currently printk is no use for early debugging because it refuses t= o actually > > > > print anything to the console unless cpu_online(smp_processor_id())= is true. > > >=20 > > > On x86-64 this is simply solved by setting the boot processor online = very early. > >=20 > > Yeah, someone suggested that. Unfortunately it doesn't work, we actuall= y > > want to call printk before we even know which cpu we're on :D >=20 > You mean smp_processor_id() returns a random value? >=20 > Then your patch is broken too because iirc it tested smp_processor_id() > before that other flag No it returns 0, but that seems to be the result of good luck rather than good management. I think I owe you a beer :) cheers --=20 Michael Ellerman IBM OzLabs wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person --=-ArSm8HUt+1BXJWalsCtU Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (GNU/Linux) iD8DBQBEbUZldSjSd0sB4dIRAj7/AJ9YA75HofsrOZH2stoQelVaHZpkfQCgjlXR faH523DCxqqBKWOtkrJ0VR8= =buwq -----END PGP SIGNATURE----- --=-ArSm8HUt+1BXJWalsCtU--