Using the "BR" Command in WDEB386.EXE

ID: Q105275

The information in this article applies to:

Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1

SUMMARY

The "BR" command in WDEB386.EXE uses the debug registers of the Intel 386 and above processors to break into the debugger on memory accesses. These accesses can be in byte, word, or dword sizes involving a read, write, or execute instruction. Because the BR command is very specific as to the type of memory access it will trap, care must be taken to choose the correct combination of BR settings in order to obtain all possible cases:


   E == execute access
   W == write access
   R == read access

   1 == byte sized access
   2 == word sized access
   4 == dword sized access

When a break into the debugger is required when a memory location is modified, set a few BR breakpoints on a Write operation giving the three different operand sizes:

BR W1 seg:off
BR W2 seg:off
BR W4 seg:off

This should cover all possible cases of the memory being touched.

Additional query words: 3.10 no32bit 3.00 breakpoint br

Keywords : kb16bitonly
Version : WINDOWS:3.0,3.1
Platform : WINDOWS
Issue type :