Messages in this thread | | | Date | Tue, 28 Oct 2014 14:31:18 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH v2 4/5] ARM: allow errata and XIP options to be enabled without ARCH_MULTIPLATFORM_STRICT |
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On Tue, Oct 28, 2014 at 03:24:38PM +0100, Arnd Bergmann wrote: > On Tuesday 28 October 2014 14:02:31 Russell King - ARM Linux wrote: > > On Tue, Oct 28, 2014 at 09:31:34PM +0800, Xia Kaixu wrote: > > > With the ARCH_MULTIPLATFORM_STRICT option, it becomes much easier to > > > enable the ERRATA options when we know at configuration time that we > > > don't care about the generic case. The previous configuration makes > > > XIP_KERNEL option fundamentally non-MULTIPLATFORM, but it's still > > > valid to select it when building for !ARCH_MULTIPLATFORM_STRICT and > > > selecting only the one machine that you want to run on. > > > > XIP_KERNEL isn't supported on anything past ARMv5 though. > > I would really like to get some of the platforms that currently use > XIP_KERNEL to use ARCH_MULTIPLATFORM in the long run. One of them > is EFM32, which is ARMv7-M.
Right, and on ARMv7-M, the restrictions against XIP_KERNEL don't apply. The restrictions on XIP_KERNEL only apply with MMU-full kernels, because of the remapping needed - the kernel is executed from flash, which is mapped separately, and that mapping needs to be setup in order to turn the MMU on.
With ARMv7-M, there is no MMU to worry about, no other mappings are required, so there is no special platform specific setup applicable.
So, I don't see any reason why XIP_KERNEL can't depend on !ARCH_MULTIPLATFORM || CPU_V7M.
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