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Major Problem With Latest CYGWIN1.DLL And Serial IO [VERIFIED!]

Hi George,

I've just downloaded your bit of code, and can happily or
sadly (however one takes it) verify that there is a problem
in cygwin regarding the initialization of comports via the
open() method.

I've also had some other problems with cygwin's behaviour
during read() of comports, cygwin doesn't seem to want to
block even when .c_cc[VMIN] is set to something like 1,2,3...

Anywayz seeing your post today has motivated me to write
my own post and bit of code to demonstrate this problem.

Good Catch!

Arash Partow

Be one who knows what they don't know,
Instead of being one who knows not what they don't know,
Thinking they know everything about all things.

* From: "George Abdelmalik" <georgeabdelmalik at hotmail dot com>
* To: cygwin at cygwin dot com
* Date: Fri, 23 Apr 2004 01:01:07 +0000
* Subject: Major Problem With Latest CYGWIN1.DLL And Serail IO
* Bcc:
Hi all,
I've encountered a problem in using serial ports (comm ports) with the latest cygwin snapshots.
The problem was first encountered in snapshot cygwin1-20040416.dll and with further testing i've
concluded that the issue remains with the most recent snapshots. These being:
- cygwin1-20040422.dll
- cygwin1-20040420.dll
- cygwin1-20040416.dll
The problem occurs when a call to open() is made. Under WIN XP the open fails
after a few seconds of blocking. Under WIN 2000, the open is successful however
calls to ioctl with TIOCMGET produce false results (i.e. obtaining the status
of DTR, RTS etc).
I think this is related to the changes 'Corinna Vinschen' made in the cygwin1-20040416.dll
snapshot, specifically:
(fhandler_base::open): Rearrange to use NtCreateFile instead of CreateFile.
This problem does not occur in snapshots previous to cygwin1-20040416.dll.
I've written a piece of code which demonstrates this issue, and have attached it to this
posting. I would appreciate it if people could verify this issue by running the attached
To compile:
make all
To run:
Tested system configurations:
P4 @ 1.6 GHz
- WIN 2000
P4 @ 1.2 GHz
I've also attached the cygcheck for the WIN XP system.



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