On Fri, Feb 17, 2017 at 12:12 PM, Andy Lutomirski [off-list ref] wrote:

At the very least, I'd want to see
MAP_FIXED_BUT_DONT_BLOODY_UNMAP_ANYTHING.  I *hate* the current
interface.

That's unrelated, but I guess w could add a MAP_NOUNMAP flag, and then
you can use MAP_FIXED | MAP_NOUNMAP or something.

But that has nothing to do with the 47-vs-56 bit issue.

How about MAP_LIMIT where the address passed in is interpreted as an
upper bound instead of a fixed address?

Again, that's a unrelated semantic issue. Right now - if you don't
pass in MAP_FIXED at all, the "addr" argument is used as a starting
value for deciding where to find an unmapped area. But there is no way
to specify the end. That would basically be what the process control
thing would be (not per-system-call, but per-thread ).

                 Linus