[resend] Allow use of MAP_TRYFIXED for better mmap()

[Todd Vierling]

On Wed, 27 Aug 2003, Alexandre Julliard wrote:

: It's not really a question of shuffling back and forth, it's that
: different users have different kernels; so if you want to ship a
: binary that works for everybody, with your method you have to stick to
: the lowest common denominator. With run-time checks you can have a
: binary that takes advantage of new kernel features, while still
: running everywhere.

That's why there is a "#ifdef MAP_TRYFIXED".  If this is available at
compile time, it is known to be available at runtime regardless of CPU
platform -- it's not an optional kernel feature.

(Besides all this, detecting this particular feature at runtime is ...
difficult at best.  The "protected" memory range is different depending on
the CPU platform.)

-- 
-- Todd Vierling <tv at pobox.com>