Re: [PATCH v5 3/4] arm64: mm: support ARCH_MMAP_RND_BITS.

[Arnd Bergmann]

On Monday 07 December 2015 10:26:34 Daniel Cashman wrote:
> > Ideally we'd remove the #ifdef around the mmap_rnd_compat_bits declaration
> > and change this code to use
> > 
> >       if (IS_ENABLED(CONFIG_COMPAT) && test_thread_flag(TIF_32BIT))
> > 
> That would result in "undefined reference to mmap_rnd_compat_bits" in
> the not-defined case, no?

No. The compiler eliminates all code paths that it knows are unused.
The IS_ENABLED() macro is designed to let the compiler figure this out.

	Arnd
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