[RFC] powerpc/mm: honor O_SYNC flag for memory map

[Segher Boessenkool]

>> You need to be a bit more careful tho. You must not allow RAM  
>> managed by
>> the kernel to be mapped non-cachable.
>
> Even if the user explicitly sets the O_SYNC flag?  IMHO, it's a bug of
> the application if it uses O_SYNC on main memory to be mmap'ed later.
> And we don't need to cover up the bug.

Is that "embedded thinking"?  Conflicts like this cause machine  
checks or
checkstops on many PowerPC implementations, we do not normally allow  
such
to be caused by userland.


Segher