Re: [PATCH v1] selftests/mm: add simple VM_PFNMAP tests based on mmap'ing /dev/mem

[David Hildenbrand]

> > Is this not pretty much equivalent to a volatile read where you're forcing
> > the compiler to not optimise this unused thing away? In guard-regions I set:
> >
> > #define FORCE_READ(x) (*(volatile typeof(x) *)x)
> >
> > For this purpose, which would make this:
> >
> > FORCE_READ(addr);
> > FORCE_READ(&addr[pagesize]);
>
> Hmmm, a compiler might be allowed to optimize out a volatile read.

Looking into this, the compiler should not be allowed to do that. So 
FORCE_READ() should work!

--
Cheers,

David / dhildenb