WinDbg Breakpoint NOT Being Hit But Code is Executed

WINDBG
1

I am using WinDbg version 6.3.9600.17298 for AMD64 on a Windows 7 x64 system to inspect a Unidrv Print Driver’s code.

The source path and breakpoints have been setup correctly. I am able to break and walk through the source code; however, there are some breakpoints that do NOT happen (and I have therefore been unable to step through the code) even though I am sure the code is executed. These breakpoints are all set in the optional rendering plugin methods and/or the DDI Hook-out functions. I know that the break points for these functions are set because the bl WindDbg command lists them as such with addresses, et cetera. I should also note that the built-in debug messages (via VERBOSE macro) are also NOT being sent to the Windbg console for these sections of code, but other sections, even code sections in the same file, are.

I know that the associated code is executed because the resulting printout is correct and the resulting *.prn file (when using print to file) is correct and it would NOT be otherwise.

Any thoughts on what might be happening and how to work around it?

2

Is it possible you are tracing through an optimised build? You may need to step through at instruction level
(‘Disassembly’ debug) to see exactly what’s happening.

-----Original Message-----
From: xxxxx@lists.osr.com [mailto:bounce-612448-
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Sent: 13 July 2016 22:08
To: Kernel Debugging Interest List
Subject: [windbg] WinDbg Breakpoint NOT Being Hit But Code is Executed

I am using WinDbg version 6.3.9600.17298 for AMD64 on a Windows 7 x64
system to inspect a Unidrv Print Driver’s code.

The source path and breakpoints have been setup correctly. I am able
to break and walk through the source code; however, there are some
breakpoints that do NOT happen (and I have therefore been unable to
step through the code) even though I am sure the code is executed.
These breakpoints are all set in the optional rendering plugin methods
and/or the DDI Hook-out functions. I know that the break points for
these functions are set because the bl WindDbg command lists them as
such with addresses, et cetera. I should also note that the built-in
debug messages (via VERBOSE macro) are also NOT being sent to the
Windbg console for these sections of code, but other sections, even
code sections in the same file, are.

I know that the associated code is executed because the resulting
printout is correct and the resulting *.prn file (when using print to
file) is correct and it would NOT be otherwise.

Any thoughts on what might be happening and how to work around it?

3

David,

Thanks for the response. I have compiler optimizations off (/0d), but stepping through the assembly may be the best way to figure out what is happening. I will give it a shot and see what I can come up with…

Thanks,
Ian