Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH v2 3/5] ARM: restrict CPU_BIG_ENDIAN configuration option | Date | Tue, 28 Oct 2014 15:37:52 +0100 |
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On Tuesday 28 October 2014 14:00:22 Russell King - ARM Linux wrote: > On Tue, Oct 28, 2014 at 09:31:33PM +0800, Xia Kaixu wrote: > > Some platforms don't work when CPU_BIG_ENDIAN is enabled. > > So It can get a dependency on !ARCH_MULTIPLATFORM_STRICT. > > What if big endian wants to build a multiplatform kernel?
They can turn off ARCH_MULTIPLATFORM_STRICT easily.
> This doesn't look right to me. Instead, we should be arranging for > those which do not work in BE mode to depend on !CPU_BIG_ENDIAN. > Yes, it's a larger patch but IMHO is a much more correct solution.
I've also asked Kaixu to put this one in, mostly for the side-effect of getting an allmodconfig kernel to be little-endian, but also because we don't really know which platforms are ok to run on big-endian. I would assume that most platforms have at least some platform-specific drivers that are not endian-clean, and even if the platform works big-endian in principle, it's unclear if everything works.
The most important aspect is probably user space though: If you build a multiplatform kernel (or one for ARMv4/5 and one for ARMv6/7) that runs on all sorts of machines, you can have a common user space that is built for ARMv4 little-endian and that will run everywhere. As soon as you enable big-endian, you have a fundamental ABI change and nothing works unless you replace the entire user space side.
Arnd
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