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Problem suspending Cygwin-based GDB from Eclipse/CDT (and some findings)


Hi,

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Until now, we have only supported Windows XP but recently we were forced to upgrade to a newer version of the cygwin1.dll (1.5.24-2) since we had to support Windows Vista, and Cygwin-based GCCs didn't work correctly with cygwin1.dll 1.5.19-4 on Windows Vista due to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 Windows Vista.

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 another process.

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
pthread functions.

* 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.


Best Regards, Stefan Bylund


-- --------------------------------- Stefan Bylund Senior Software Engineer Enea Skalholtsgatan 9, Box 1033, SE-164 21 Kista, Sweden Direct: +46 8 50 71 43 25 Mobile: +46 709 71 43 25 stefan.bylund@enea.com www.enea.com --------------------------------- Enea - Embedded for Leaders ---------------------------------


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