Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Mon, 28 Apr 2003 12:00:45 -0600

Chris,

I suspect that your problem with fd_set below is caused by side
effects in the cygwin header files occurring when POSIX_SOURCE
was being defined in CONFIG.Common.win32-x86-cygwin. Some time
back, for lack of a better idea, I removed the definition of
POSIX_SOURCE there but I must confess that I don't know the full
impact of that change.

Executive summary: 
The latest snapshot of EPICS R3.14 is building with cygwin, but
there are still some significant problems detected by the
regression tests. It's possible that these problems could be
resolved with some further effort in the debugger. 

I should add however that the performance of the cygwin layered
approach compared to the native windows port is significantly
worse, and there are some good quality free native windows
targeting compilers such as Borland bcc and gnu gcc if you are
opposed to buying the MS compiler, and you don't need a POSIX
compatibility layer for windows.

I am attaching some messages I sent to Janet awhile back with the
latest status on my efforts to get R3.14 to work with cygwin.
Since that message was sent I have made changes in the
organization of the code that permit avoidance of use of the
broken signaling features of cygwin to interrupt blocking recv()
and send() calls. I currently have the cygwin interface
configured to use shutdown() for this purpose, but I have not yet
confirmed that this is working. 

>   Thanks for the tips I'll give that a try. Does anyone know
> the answer to Eric's question about win98

The answer is that the native windows interface of EPICS R3.14
does link with one function that is available only in NT/2000/XP.
However if you use delayed binding of the DLL's then the code
should successfully detect 95/98/ME and avoid calling this
function. The function involved is TryEnterCriticalSection and
its use permits significantly improved performance on NT/2000/XP.
Given the marginal reliability of 95/98/ME then their use should
probably be avoided in production systems.

The cygwin interface of EPICS R3.14 is another matter. This is
purely dependent on cygwin which probably addresses its windows
version compatibility range within its documentation.

Jeff

> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]
> Sent: Monday, April 28, 2003 5:25 AM
> To: Eric Norum
> Cc: [email protected]
> Subject: Re: Building 3.14.1 under cygwin environment
> 
> Eric Norum wrote:
> 
> > What I usually do in situations like this is to issue the
> compile
> > command with -c changed to -E so I can see exactly what's
> getting passed
> >   on from the preprocessor to the compiler.  The offending
> line is:
> >      fd_set fdSets[fdrNEnums];
> > This makes me think that the likely cause of the problem is
> that
> > 1) fd_set is not typefed properly.  (to check, run the output
> of the
> > '-E' compile through 'grep fd_set'.
> > OR
> > 2) fdSets is being defined as a preprocessor macro somewhere
> in some
> > cygwin header file.  About the only thing to do here is to
> 'grep fdSets'
> > on all the header files.
> >
> > BTW -- is EPICS likely to work on win98???
> >
> 
>   Thanks for the tips I'll give that a try. Does anyone know
> the answer
> to Eric's question about win98 ? This is my first foray into
> running
> Epics/Channel Access from a Windows environment so any help
> would be
> appreciated. Also, does anyone know what the situation is with
> XP ?
> 
>       Chris Mayer
> _______________________________________________________________
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System