From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Kerr Subject: Re: [PATCH 06/11] arm-dt: postpone machine detection until setup_arch with CONFIG_ARM_DEVTREE Date: Tue, 5 Jan 2010 06:26:54 +0800 Message-ID: <201001050926.54286.jeremy.kerr@canonical.com> References: <1261479296.247430.731563214048.6.gpush@pororo> <4B421903.4050200@simtec.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B421903.4050200-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Ben Dooks Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Ben, > > When we're using CONFIG_ARM_DEVTREE, we need to postpone machine > > detection until later in setup_arch. Because ARM_DEVTREE depends on > > !DEBUG_LL, we don't need the mdesc this early anyway. > > > > We'll add support for ARM_DEVTREE && DEBUG_LL later. > > Why not add a specific machine type for 'this is device tree' and > then these routines don't even need to #ifdef. It would especially > be good as it allows dt and non-dt machines to coexist in the same > kernel together. Mainly because this doesn't gain us much; the machine_desc that is discovered from this new machine type would not have the correct data (phys_io & io_pg_offset) required for early setup (used for DEBUG_LL). We could conditionally skip the detection if we see a DT machine type, but then we'd need to add similar checks for all the paths where the machine_desc is used. However, my goal is indeed to allow DT and non-DT machines to coexist as much as possible, this patch is more a temporary workaround while I figure out how to handle the DEBUG_LL stuff nicely for DT cases. Cheers, Jeremy