Defrag Tools: #21 - WinDbg - Memory User Mode

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Description

In this episode of Defrag Tools, Andrew Richards, Chad Beeder and Larry Larsen continue looking at the Debugging Tools for Windows (in particular WinDbg). WinDbg is a debugger that supports user mode debugging of a process, or kernel mode debugging of a computer.

This installment goes over the commands used to show the memory used in a user mode debug session. We cover these commands:

  • !address -summary
  • !address <addr>
  • !vprot <addr>
  • !mapped_file <addr>

Make sure you watch Defrag Tools Episode #1 for instructions on how to get the Debugging Tools for Windows and how to set the required environment variables for symbols and source code resolution.

Resources:
Microsoft Windows SDK for Windows 7 and .NET Framework 4
Sysinternals VMMap
Performance and Memory Consumption Under WOW64
MEMORY_BASIC_INFORMATION structure
Memory Protection Constants

Timeline:
[00:50] - Live Debug of Notepad
[01:10] - VMMap of Notepad
[02:08] -
Virtual Address Space summary (!address -summary)
[04:30] - 'Large Address Space Aware' increases the VA space from 2GB to 4GB

[08:11] - Memory Mapped Files
[10:11] - Memory Type, State and Protection (inc. Guard Pages)
[21:22] - Allocation Base vs. Base Address (!address <addr>)
[26:52] - Virtual Protection shows the Alloc. Base Protection (!vprot <addr>)
[29:14] - Mapped Files (!mapped_file <addr>)

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    The Discussion

    • User profile image
      tgrt

      I love this series. I know they're all about the tools, but don't be afraid to go on a slight tangent to cover some topic that isn't necessarily well understood. You guys seem to know where these points are and you do a great job of explaining briefly, but in some cases I don't think it'd hurt to expound on it.

    • User profile image
      Andres

      Richard, you really need to stop drinking sodas before a session like this, you are burping all the time, it is really irritating.

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