CONFIG_* symbols in UAPI headers?

[Christoph Hellwig]

I just stumbled over the MAP_UNINITIALIZED defintion, initially
added by:

commit ea637639591def87a54cea811cbac796980cb30d
Author: Jie Zhang <jie.zhang@xxxxxxxxxx>
Date:   Mon Dec 14 18:00:02 2009 -0800

    nommu: fix malloc performance by adding uninitialized flag

The defintion depends on CONFIG_MMAP_ALLOW_UNINITIALIZED, which
will never be set by userspace.  How is this supposed to work?

Shoudn't we define the symbol unconditionally and just turn it
into a no-op in the implementation?


There are a few similar issues, like struct elf_prstatus having
a different layout depending on CONFIG_BINFMT_ELF_FDPIC, or
MAX_SHARED_LIBS defending on CONFIG_BINFMT_SHARED_FLAT.