FIX: CVW 4.0 Does Not Always Stop on Breakpoints in DLL

The information in this article applies to:

• Microsoft CodeView for Windows, versions 4.0 and 4.01

SYMPTOMS

Microsoft CodeView for Windows versions 4.0 and 4.01 may not stop on a breakpoint in a DLL. When setting the breakpoint, the breakpoint list (BL) shows that this breakpoint is virtual. Even after the DLL is loaded, this breakpoint is still listed as virtual.

CAUSE

This problem occurs when you have more than one copy of the same DLL on your disk. CodeView differentiates between these DLLs even if they are exactly the same.

CodeView is allowing the user to load the symbolic information for one copy, but Windows itself is loading the other copy. Because the symbolic information is used to set breakpoints, breakpoints that are set on symbolic information of a DLL that is not ever loaded by Windows will always be virtual.

RESOLUTION

The best resolution for this problem is to remove all but one copy of the DLL from the disk.

This problem was corrected in CodeView 4.1. When loading multiple copies of symbolic information for the same DLL or .EXE, CodeView 4.1 generates the following warning:

   CV2213 Warning: preloaded symbols may not match 'MyDLL.DLL'

STATUS

Microsoft has confirmed this to be a problem in Microsoft CodeView versions 4.0 and 4.01. This problem was corrected in Microsoft CodeView version 4.1.

MORE INFORMATION

CodeView will only stop on a breakpoint that is associated with an address. Virtual breakpoints are breakpoints that are set on a section of code that has not been loaded into memory yet. When the code is loaded into memory, the breakpoint becomes a physical breakpoint, and is associated with a memory address.

Virtual breakpoints are displayed with a "V" before the "D" or "E" for disabled or enabled, respectively.