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Problem suspending Cygwin-based GDB from Eclipse/CDT (and some findings)
- From: Stefan Bylund <steby at enea dot se>
- To: cygwin at cygwin dot com
- Date: Mon, 03 Dec 2007 16:04:26 +0100
- Subject: Problem suspending Cygwin-based GDB from Eclipse/CDT (and some findings)
We have a source code debug solution based on Eclipse / CDT / GDB / GCC
/ Cygwin DLL. We are using Eclipse 3.2.2 / CDT 3.1.2 / GDB 6.3 / GCC
3.4.4 / Cygwin DLL 1.5.19-4 (cygwin1.dll).
Until now, we have only supported Windows XP but recently we were forced
to upgrade to a newer version of the cygwin1.dll (1.5.24-2) since we had
to support Windows Vista, and Cygwin-based GCCs didn't work correctly
with cygwin1.dll 1.5.19-4 on Windows Vista due to heap errors in
cygwin1.dll. However, GDB works fine with cygwin1.dll 1.5.19-4 on
Unfortunately, I just discovered that suspending GDB from Eclipse/CDT no
longer works. So I tried all versions of the cygwin1.dll from 1.5.19-4
to the forthcoming 1.5.25-3 and found that starting from version
1.5.20-1, the signal handling in cygwin1.dll seems to have changed in
such a way that suspending GDB from Eclipse/CDT no longer works. Note
that versions before 1.5.19-4 of the cygwin1.dll also works correct with
respect to suspending GDB from Eclipse/CDT.
By searching the cygwin mailing list, it seems that it is a general
problem when trying to programatically send a SIGINT from one process to
I looked at the cygwin change list from 1.5.19-4 to 1.5.20-1
(http://cygwin.com/ml/cygwin-announce/2006-07/msg00000.html) and noticed
the following signal-related changes:
* cgf: When sending signals, assume that any code which is not directly
associated with a DLL or an executable is user code.
* cgf: Pass cygwin signals to gdb. Fix the dreaded SIGSEGV found in some
* corinna: Implement sigignore and sigset.
* cgf: Make SA_RESTART sigaction flag work more like linux.
It seems that one or more of the changes listed above (or some other
change(s) described in
http://cygwin.com/ml/cygwin-announce/2006-07/msg00000.html) is the cause
of this problem. It is a bit ironic that one of the changes mentions
passing cygwin signals to gdb since it is exactly this functionality
that is now broken but, from our experience, worked in 1.5.19-4.
I'm cross posting this mail to the CDT mailing list as well, since there
may be other Eclipse/CDT users interested in this issue.
Is there anything I can do to help in finding out why versions starting
from 1.5.20-1 of the cygwin1.dll no longer supports programatically
sending a SIGINT from one process to another? If nothing else, I can at
least help out with testing.
Senior Software Engineer
Box 1033, SE-164 21 Kista, Sweden
Direct: +46 8 50 71 43 25
Mobile: +46 709 71 43 25
Enea - Embedded for Leaders
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