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Message-ID: <3A24359B.9CABBE43@delcomsys.com>
Date: Tue, 28 Nov 2000 17:45:47 -0500
From: Patrick Doyle <wpd AT delcomsys DOT com>
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To: cygwin AT cygwin DOT com
Subject: Re: Debugging cygwin1.dll
References: <3A242AC7 DOT 2C9B0DFD AT delcomsys DOT com> <20001128173449 DOT C4114 AT redhat DOT com>
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Thanks... I'll give these ideas & hints a try.

--wpd


Christopher Faylor wrote:
> 
> On Tue, Nov 28, 2000 at 04:59:35PM -0500, Patrick Doyle wrote:
> >I am certain I have seen this on the mailing list before, but I cannot
> >seem to find it.  Could somebody please summarize tips for debugging
> >cygwin1.dll.  I have several specific questions.  If somebody would care
> >to answer them, I would be very grateful.
> >
> >1) Do all of the various _printf calls in the source (debug_printf(),
> >syscall_printf, etc...) wend their way to strace, or do they go
> >somewhere else?  If they go somewhere else, how can I capture them?
> 
> Look at winsup/cygwin/include/sys/strace.h.  This is where most of the
> foo_printf calls are defined.
> 
> "grep is your friend"
> 
> >2) If I wanted to step into cygwin calls with GDB, (how) can I do that?
> 
> You set breakpoints on line numbers in cygwin.  Either set a breakpoint
> on main and wait for the DLL to be loaded or use the 'dll cygwin1'
> command to preload the symbols for the DLL and then set breakpoints.
> 
> For some reason you can't set a breakpoint directly on a cygwin function
> if you preload the symbols with 'dll cygwin1.dll'.
> 
> You can set a breakpoint on the first line of the function, though.  So,
> 
> bp _read
> 
> won't work
> 
> but
> 
> bp syscalls.cc:204
> 
> will.
> 
> >3) I have successfully built cygwin1.dll from the CVS snapshot.  If I
> >want to try it, do I have to exit all of my cygwin apps, install it in
> >/bin, and then restart my cygwin apps?
> 
> Yes.
> 
> >Or can I run a specific cygwin app using my new DLL without going
> >through all of this?
> 
> Not safely.  However, if you configure cygwin with --enable-debugging
> this will produce a DLL which does not interfere as much with other
> cygwin1.dll's on the system.  I keep a gdb with its own stable
> cygwin1.dll, built with --enable-debugging, sitting in its own directory
> for debugging cases where cygwin1.dll is severely broken.
> 
> cgf
> 
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