Re: updating COMPAT_LINUX for linux 2.6.x support (take 2)

[Chuck Silvers <chuq%chuq.com@localhost>]

On Sat, Jun 05, 2010 at 01:02:12PM +1000, matthew green wrote:
> 
> >  - fix obreak() to honor RLIMIT_AS as well as RLIMIT_DATA.
> >    this will affect native processes as well as linux ones,
> >    but it seems appropriate.
> 
> if you're going to do this, you may as well just make RLIMIT_AS and
> RLIMIT_DATA refer to the same thing (and make that RLIMIT_AS.)
> 
> when implementing RLIMIT_AS i was confused about how these would
> interact, and clearly there was a problem. :)
> 
> there's also RLIMIT_STACK, but it has additional semantics that
> make it different to both _AS and _DATA, further adding to the
> confusion..

combining RLIMIT_AS and RLIMIT_DATA sounds confusing.

I looked at what linux does here: RLIMIT_DATA only affects brk(),
whereas RLIMIT_AS affects all mappings.  that's what we were trying
to do too, but I think we just put the check in the wrong place...
if we move it to uvm_map() instead of uvm_mmap(), that will catch
brk() and stack usage too.  let me try that and see what breaks.

-Chuck