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Re: HEADSUP: cygserver now has MSG, SEM and SHM support

On Wed, Nov 26, 2003 at 10:38:29PM -0500, Harold L Hunt II wrote:
> Christopher Faylor wrote:
> >The gotcha here, though, is that you still have to install cygserver
> >and get it running.  Corinna has provided install scripts to make
> >that to happen but experience shows us that there will probably be
> >some tweaking required before everything is perfect.

You just have the same gotcha with cygipc.  So nothing really new
with this.

> Ah, well, in the case of XWin.exe, it detects whether the an SHM 
> allocation succeeds or fails and enables/disables the X SHM extension 
> appropriately.  Each X application tests for presence of the SHM 
> extension and doesn't try to use it if it is not there.
> Thus, all of our apps and libs link against cygipc.  We can still build 
> with SHM support but it won't actually be used unless things are setup 
> properly, as you described.

Ok, I don't know how that's implemented in cygipc so I think it might
be necessary to mention that:

The implementation of the MSG, SEM and SHM functions in Cygwin are so
that if the functions are not available (be it that CYGWIN doesn't
contain the word "server" or Cygserver isn't running) not only set
errno to ENOSYS, but they also raise a SIGSYS.

So it's crucial that your code handles that signal.  At least, it
should ignore it (signal(SISYS, SIG_IGN)).


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                      
Red Hat, Inc.

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