Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752783AbZKPQ53 (ORCPT ); Mon, 16 Nov 2009 11:57:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752494AbZKPQ53 (ORCPT ); Mon, 16 Nov 2009 11:57:29 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:55417 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751927AbZKPQ52 (ORCPT ); Mon, 16 Nov 2009 11:57:28 -0500 Date: Mon, 16 Nov 2009 16:57:16 +0000 From: Russell King - ARM Linux To: Brian Swetland Cc: Pavel Machek , Arve Hj?nnev?g , kernel list , linux-arm-kernel Subject: Re: [PATCH 2/3] msm: add minimal board file for HTC Dream device Message-ID: <20091116165716.GD3568@n2100.arm.linux.org.uk> References: <20091102104949.GA23456@elf.ucw.cz> <20091116163659.GB3568@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1441 Lines: 33 On Mon, Nov 16, 2009 at 08:43:20AM -0800, Brian Swetland wrote: > What's the best way to handle a situation where there is no valid > debug uart? Could the arch/platform require DEBUG_LL be unset via > Kconfig directives if it is configured in a way where there is no > valid debug uart? You're the first to have that issue. Everyone else has a UART they can always direct stuff at. However, I believe you're making the issue far larger than it really is. 1. If you define the DEBUG_LL macros to be empty, printascii() etc will not touch any mapping. 2. If no mapping is going to be touched by printascii(), does it matter whether a UART is mapped via this early mapping stuff? The answer to (2) is no. So, you can still arrange for these fields to be populated with a valid value even if you don't intend to use the resulting mapping. And so there's no need to force DEBUG_LL to be unset. If you really have no values you can use, make sure you set io_pg_offst to 0x3ffc - the last offset in the L1 page table. This will cause the code to write a single dummy entry at the very top of the page table, which will then be overwritten by the generic ARM arch code for its own use. -- 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/