On Monday 07 December 2015 10:26:34 Daniel Cashman wrote:

quoted

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