Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752258Ab3DSRPT (ORCPT ); Fri, 19 Apr 2013 13:15:19 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:39349 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751211Ab3DSRPP (ORCPT ); Fri, 19 Apr 2013 13:15:15 -0400 Date: Fri, 19 Apr 2013 18:14:56 +0100 From: Catalin Marinas To: Peter Maydell Cc: Will Deacon , "linaro-kernel@lists.linaro.org" , Patch Tracking , Marc Zyngier , "linux-kernel@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" , "linux-arm-kernel@lists.infradead.org" , Pranavkumar Sawargaonkar Subject: Re: [RFC] arm64: Early printk support for virtio-mmio console devices. Message-ID: <20130419171455.GA43450@MacBook-Pro.local> References: <20130419092752.GB13283@mudshark.cambridge.arm.com> <20130419093953.GD13283@mudshark.cambridge.arm.com> <20130419161201.GA5383@localhost.cambridge.arm.com> <20130419162226.GB5383@localhost.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1111 Lines: 24 On Fri, Apr 19, 2013 at 05:33:18PM +0100, Peter Maydell wrote: > On 19 April 2013 17:22, Catalin Marinas wrote: > > earlyprintk is used for debugging early problems, like DT parsing. You > > don't have to use it unless you are debugging something. Without > > earlyprintk you just get a normal console during boot, based on the DT > > description. > > The command line lives in the DTB anyway so if you can't look > in the DTB you can't get at earlyprintk config either way. Linux indeed looks in the DT for the command line and that's what's triggering the earlyprintk console but at that stage the DT is flat. Unflattening the DT happens later (it requires slab allocator). I initially thought about extracting the early console device from the DT but when it is flat you can't parse the full hierarchy to get its address. -- Catalin -- 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/