Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753344AbaKQOwx (ORCPT ); Mon, 17 Nov 2014 09:52:53 -0500 Received: from arrakis.dune.hu ([78.24.191.176]:59741 "EHLO arrakis.dune.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752797AbaKQOwv (ORCPT ); Mon, 17 Nov 2014 09:52:51 -0500 MIME-Version: 1.0 In-Reply-To: <3480616.V2TMJFc7uE@wuerfel> References: <1416097066-20452-1-git-send-email-cernekee@gmail.com> <50587083.ieLlCR4VrM@wuerfel> <3480616.V2TMJFc7uE@wuerfel> From: Jonas Gorski Date: Mon, 17 Nov 2014 15:52:15 +0100 Message-ID: Subject: Re: [PATCH V2 22/22] MIPS: Add multiplatform BMIPS target To: Arnd Bergmann Cc: Kevin Cernekee , Ralf Baechle , Florian Fainelli , Jon Fraser , dtor@chromium.org, Thomas Gleixner , Jason Cooper , Linux MIPS Mailing List , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 17, 2014 at 1:16 PM, Arnd Bergmann wrote: > I still think this is different in the sense that ARM multiplatform > support is about combining platforms from separate mach-* directories, > while your approach was to rewrite multiple mach-* directories into > a single new one that remains separate from the others. While this is > a great improvement, it doesn't get you any closer to having a > combined BMIPS+RALINK+JZ4740+ATH79 kernel for instance. I don't know > if such a kernel is something that anybody wants, or if it's even > technically possible. > > If you wanted to do that however, starting with BMIPS you'd have > to make it possible to define a new platform without the > arch/mips/include/asm/mach-bmips/ directory (this should be possible > already, so the hardest part is done), replace all global function > calls (arch_init_irq, prom_init, get_system_type, ...) with generic > platform-independent implementations or wrappers around per-platform > callbacks, and move the Kconfig section for CONFIG_BMIPS_MULTIPLATFORM > outside of the "System type" choice statement. > Until you do that, your platform isn't "more multipliplatform" than > the others really, it just abstracts the differences between some > SoCs nicer than most. I guess a big blocker for such a real mips multiplatform kernel is that there is still no defined (standard) interface for passing a device tree to the kernel from the bootlader on mips, unlike on arm (at least I'm not aware of any). And unless there is one, having a multiplatform kernel does not make much sense, as there is no sane way to tell apart different platforms on boot. But maybe we should just define a way, and require new platforms to use it ;-) Jonas -- 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/