From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Tue, 6 Nov 2012 21:14:49 +0000 Subject: Building for MMU-less vexpress targets In-Reply-To: References: <20121105173640.GR3351@mudshark.cambridge.arm.com> <201211061733.44781.arnd@arndb.de> Message-ID: <201211062114.49933.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 06 November 2012, Nicolas Pitre wrote: > Maybe you are confused by CONFIG_ARCH_MTD_XIP where special support is > needed in order to make writable MTD devices compatible with a XIP > kernel located on them. That is indeed only available for ARCH_PXA and > ARCH_SA1100. Ok, I see. > I really think that it makes no sense at all to support !MMU kernels in > a multi-platform kernel build, even if the set of included platforms > were all !MMU. The kernel has to be linked for the physical address of > the target and not a common invariant virtual address. There are two separate aspects here: One is to run a kernel on !MMU that is built to support multiple platforms. I agree that this is rather pointless and not interesting. The other point is being able to build such a kernel, and this is what Will seems to be interested in more. We have made VEXPRESS depend on MULTIPLATFORM, which broke support for building a non-MMU vexpress kernel, and I think we should fix that. The two options are either to make vexpress be single-platform when building for !MMU, or to allow multiplatform kernels to be built without MMU support in principle. I think the second option is more logical and avoids complex Kconfig constructs. Arnd