Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968435Ab3DSQW6 (ORCPT ); Fri, 19 Apr 2013 12:22:58 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:38400 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967726Ab3DSQW4 (ORCPT ); Fri, 19 Apr 2013 12:22:56 -0400 Date: Fri, 19 Apr 2013 17:22:26 +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: <20130419162226.GB5383@localhost.cambridge.arm.com> References: <20130419090558.GA13283@mudshark.cambridge.arm.com> <20130419092752.GB13283@mudshark.cambridge.arm.com> <20130419093953.GD13283@mudshark.cambridge.arm.com> <20130419161201.GA5383@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: 1466 Lines: 31 On Fri, Apr 19, 2013 at 05:14:36PM +0100, Peter Maydell wrote: > On 19 April 2013 17:12, Catalin Marinas wrote: > > On Fri, Apr 19, 2013 at 11:05:47AM +0100, Peter Maydell wrote: > >> Please make the kernel pick the device out of the device tree > >> blob. The whole point of device tree is that it's how to tell > >> the kernel where things live -- making kvmtool/QEMU and/or the > >> user also have to mess with the kernel command line is awkward > >> and annoying. > > > > For a normal console device, it indeed needs to get it from the DT. For > > early console, you want it earlier than DT parsing so we pass it on the > > kernel command line via the earlyprintk= parameter. > > You should fix your DT handling code so you can get at the info > when you need it rather than pushing the problem into bootloaders > and QEMU, please. DT is your data structure so feel free to > (re)design it so relevant information can be accessed early > if that's useful. 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. -- 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/