Serial port conformance tests

[Damjan Jovanovic]

On Tue, Mar 24, 2009 at 12:06 AM, Chris Teague <chris.teague at gmail.com> wrote:
> I'm new to wine, looking into serial communications.  I have a failing
> scenario in a application, and I'd like to write a conformance test to
> demonstrate/document the issue.  I looked in dlls/ntdll/tests but did
> not see any serial port related tests - did I miss them or do none
> exist yet?  Assuming none exist, a very useful tool would be a serial
> port loopback device.  Rather than require conformance testers to
> attach a hardware loopback device (NULL modem) to a physical port,
> could we create some virtual ports in wine and connect them together?
> Maybe com98 and com99 for example?  Anything written to one of the
> ports would be sent to the other one.  On Windows this can be done
> with a device driver, one example is com0com
> (http://com0com.sourceforge.net/).
> Is this a reasonable approach?  Thanks,
> Chris
>
>
>

What's wrong, does nobody care or is it not worth it? Well I care, and
I think it's very much worth it. The number of serial port bugs in
Bugzilla alone, seems to indicate a dire need.

I saw one of the BSDs has a null modem driver that emulates a pair of
connected serial ports as a standard part of the kernel
(http://fxr.watson.org/fxr/source/dev/nmdm/nmdm.c), while Linux not
only hasn't got it, but when a guy sent a patch into LKML some years
ago it got... completely ignored (found that mail once by accident
after hours of googling, couldn't find it again).

With a virtual serial port you can do all sorts of nifty things,
serial to RFC 2217 allowing access to remote serial port hardware,
sharing read-only hardware like GPSes over several virtual serial
ports, and monitoring communication between an application and a real
serial port. "Mighty handy for use with serial console in Vmware"
reads a comment in the BSD driver. Regression testing Wine is just one
useful side effect.

So I'll be resuming my work on a virtual serial port kernel module for
Linux. It's a shame we still don't have one in 2009.

Damjan