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Re: [Xen-devel] [PATCH] fix build when CONFIG_COMPAT disabled

On 11/1/07 16:31, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

>> Should we bother to #ifdef where we don't need to? It's ugly and the
>> compiler should be able to remove dead code where a condition evaluates to
>> zero at compile time: we already have IS_COMPAT(d) hardcoded to zero if
>> !CONFIG_COMPAT, which is enough to give the compiler a fair chance.
> Generally no, but in the one case in the patch we have to, as the structure
> member (mm_arg_xlat_l3) doesn't exist without CONFIG_COMPAT.

CONFIG_COMPAT isn't a real config option though. It's a function of the
architecture we're building for. So we don't need ifdef CONFIG_COMPAT in any
x86/64-specific code.

I'm very keen to get rid of CONFIG_* where possible. In x86 code we can
variously remove ifdefs or turn them into CONFIG_X86_64. We probably need to
keep CONFIG_COMPAT in some common code I guess.

This really follows my view that much of this new code should simply be
viewed as an always-on x86/64 extension, and that code should be propagated
down into arch/x86 and arch/x86/x86_64 as much as possible to reflect that.

 -- Keir

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