Re: [PATCH] Introduce compat_u64 and compat_s64 types

From: David Woodhouse
Date: Sat Jun 16 2007 - 05:38:27 EST


On Fri, 2007-06-15 at 11:31 +0200, Arnd Bergmann wrote:
> Hopefully, this patch improves the situation, it introduces two
> new types, compat_u64 and compat_s64. These are defined on all
> architectures to have the same size and alignment as the 32 bit
> version of u64 and s64.

Will GCC know that it needs to emit code to handle that (mis)alignment?
Preliminary tests show that it does load the value bytewise if we use
the 'packed' attribute structure on ppc64, but doesn't if we use
compat_u64. But then, I don't think it actually _needs_ to handle it n
ppc64 anyway, so maybe that's not such a good test.

I'll send a simple patch to fix the bug for now, just making the new
wrapper conditional on X86_64||IA64.

--
dwmw2

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