Re: configure and mmap on Cygwin

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Wed, Jul 16, 2003 at 05:39:22PM -0300, Fr?d?ric L. W. Meunier wrote:
> I noticed configure always return
> 
> checking for working mmap... no

Yeah, that's unfortunate.  I'm seeing the same all the time.

> I found the following posts from Corinna
> 
> http://www.cygwin.com/ml/cygwin/2002-04/msg00412.html
> http://mail.gnu.org/archive/html/autoconf-patches/2000-10/msg00241.html
> 
> The question is if I should just ignore this test or add
> #define HAVE_MMAP 1 to config.h before make.

It depends.  The Cygwin mmap implementation should work in 99% of the
cases.  There's one case which will never work:

   mem = malloc(sizeof(blah));
   mmap (mem, ..., MAP_FIXED, ...);

since Windows doesn't support memory maps on already allocated memory.
If your application does this (not many today), you're out of luck. 
Otherwise you should be fine using mmap.

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin@cygwin.com
Red Hat, Inc.

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