From patchwork Tue Nov 6 18:34:44 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 1706081 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id F2D4DDFE75 for ; Tue, 6 Nov 2012 18:37:36 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TVnzG-0001SM-FR; Tue, 06 Nov 2012 18:34:58 +0000 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TVnzA-0001Rx-1P for linux-arm-kernel@lists.infradead.org; Tue, 06 Nov 2012 18:34:55 +0000 Received: from mudshark.cambridge.arm.com (mudshark.cambridge.arm.com [10.1.79.58]) by cam-admin0.cambridge.arm.com (8.12.6/8.12.6) with ESMTP id qA6IYkE7009874; Tue, 6 Nov 2012 18:34:46 GMT Date: Tue, 6 Nov 2012 18:34:44 +0000 From: Will Deacon To: Arnd Bergmann Subject: Re: Building for MMU-less vexpress targets Message-ID: <20121106183444.GJ30931@mudshark.cambridge.arm.com> References: <20121105173640.GR3351@mudshark.cambridge.arm.com> <201211051908.34291.arnd@arndb.de> <20121106122011.GE29853@mudshark.cambridge.arm.com> <201211061733.44781.arnd@arndb.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <201211061733.44781.arnd@arndb.de> User-Agent: Mutt/1.5.21 (2010-09-15) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20121106_133452_369931_BEEBFD72 X-CRM114-Status: GOOD ( 18.39 ) X-Spam-Score: -7.6 (-------) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-7.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at http://www.dnswl.org/, high trust [217.140.96.50 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.7 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Pawel Moll , "linux-arm-kernel@lists.infradead.org" X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org On Tue, Nov 06, 2012 at 05:33:44PM +0000, Arnd Bergmann wrote: > On Tuesday 06 November 2012, Will Deacon wrote: > > nommu-XIP kernels are a different kettle > > of fish, but we don't care about a decompressor there. > > XIP is only supported on ARCH_PXA and ARCH_SA1100. I don't see either > of them moving to CONFIG_MULTIPLATFORM any time soon, given how much > work that would be. ARCH_MMP should be possible in the future, but > has never supported XIP so far. Indeed, although I expect systems with M-class CPUs to make more use of XIP (I believe Uwe's board does this and uses the framebuffer for main memory). > > The real problem will hit with things like CONFIG_DRAM_BASE, where !MMU > > can't realistically support multiple platforms, so allowing > > ARCH_MULTIPLATFORM doesn't feel quite right either... > > Anybody who wants to build a !MMU kernel already needs to tweak the > configuration quite a lot and usually knows more about the system than > a typical end user. Having to pick the correct DRAM_BASE probably > isn't too bad in that case, as long as the kernels actually build. Ok, that's fair enough. Patch below. Cheers, Will --->8 ARM: nommu: remove MMU dependency from ARCH_MULTIPLATFORM ARCH_MULTIPLATFORM is the only way to select ARCH_VEXPRESS, so remove the dependency on MMU and instead use it to predicate the selection of ARM_PATCH_PHYS_VIRT. Although running a multi-platform kernel on a selection of MMU-less targets might not yet be possible, the thing should build and targetting a nommu platform is already a fairly involved exercise. Cc: Arnd Bergmann Cc: Pawel Moll Signed-off-by: Will Deacon Acked-by: Arnd Bergmann diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 335e220..5758cfb 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -264,8 +264,7 @@ choice config ARCH_MULTIPLATFORM bool "Allow multiple platforms to be selected" - depends on MMU - select ARM_PATCH_PHYS_VIRT + select ARM_PATCH_PHYS_VIRT if MMU select AUTO_ZRELADDR select COMMON_CLK select MULTI_IRQ_HANDLER