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Created page with "{{IBM-Reprint}} {{KernelDebugRef}} <p>Before you begin debugging in a VM Start session, you must establish interrupt vectors 1 and 3. Issue the command DD %%0 to see what the vectors should be, and then issue the following commands to set them to their correct values:</p> <pre> E &amp.0:4 12 67 00 1d E &amp.0:c 57 67 00 1d </pre> <p>To debug a trap 6 or an incorrect-output problem, set a breakpoint at the <h2>VMINT21</h2> entry point.</p> <p>You..."
 
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<p>Before you begin debugging in a VM Start session, you must establish interrupt vectors 1 and 3. Issue the command DD %%0 to see what the vectors should be, and then issue the following commands to set them to their correct values:</p>
<p>Before you begin debugging in a VM Start session, you must establish interrupt vectors 1 and 3. Issue the command DD %%0 to see what the vectors should be, and then issue the following commands to set them to their correct values:</p>
<pre>
           E &0:4 12 67 00 1d
 
           E &0:c 57 67 00 1d
           E &amp.0:4 12 67 00 1d
           E &amp.0:c 57 67 00 1d
 
 
</pre>
<p>To debug a trap 6 or an incorrect-output problem, set a breakpoint at the <h2>VMINT21</h2> entry point.</p>
<p>To debug a trap 6 or an incorrect-output problem, set a breakpoint at the <h2>VMINT21</h2> entry point.</p>
<p>You can find the segment of FSFILTER by looking at the <h2>INT 20h</h2> or <h2>INT 21h</h2> vectors (0:80 and 0:84, respectively). The offset of <h2>VMINT21</h2> is hex 330. Trace through all of the <h2>INT 21</h2> calls until the error is observed. Run the test again to the last successful <h2>INT 21</h2>, then begin stepping through the code until the error is found.</p>
<p>You can find the segment of FSFILTER by looking at the <h2>INT 20h</h2> or <h2>INT 21h</h2> vectors (0:80 and 0:84, respectively). The offset of <h2>VMINT21</h2> is hex 330. Trace through all of the <h2>INT 21</h2> calls until the error is observed. Run the test again to the last successful <h2>INT 21</h2>, then begin stepping through the code until the error is found.</p>
<p>A method of eliminating FSFILTER as the component with the problem is to set up a test case that is executed from the diskette. This way, you can execute a VM Start session without installing FSFILTER. If the problem still occurs, then FSFILTER is not the cause of the problem.</p>
<p>A method of eliminating FSFILTER as the component with the problem is to set up a test case that is executed from the diskette. This way, you can execute a VM Start session without installing FSFILTER. If the problem still occurs, then FSFILTER is not the cause of the problem.</p>

Revision as of 00:47, 4 May 2025

Reprint Courtesy of International Business Machines Corporation, © International Business Machines Corporation

Kernel Debugger Reference
  1. Introduction
  2. Installing the Kernel Debugger
  3. The T Terminal Emulator
  4. Entering the Debugger
  5. Expressions
  6. Operator Precedence
  7. Binary Operators
  8. Unary Operators
  9. Numbers
  10. Strings
  11. Symbol Files
  12. Using Kernel Debugger Commands
  13. The Breakpoint (BP) Command
  14. Breakpoint Commands
  15. External Commands
  16. Using Default Commands
  17. External Debugger Commands
  18. Setting Useful Breakpoints
  19. Debugging Kernel Device Drivers
  20. Debugging VM Start Sessions
  21. Debugging a Remote System
  22. Notices

Before you begin debugging in a VM Start session, you must establish interrupt vectors 1 and 3. Issue the command DD %%0 to see what the vectors should be, and then issue the following commands to set them to their correct values:

          E &0:4 12 67 00 1d
          E &0:c 57 67 00 1d

To debug a trap 6 or an incorrect-output problem, set a breakpoint at the

VMINT21

entry point.

You can find the segment of FSFILTER by looking at the

INT 20h

or

INT 21h

vectors (0:80 and 0:84, respectively). The offset of

VMINT21

is hex 330. Trace through all of the

INT 21

calls until the error is observed. Run the test again to the last successful

INT 21

, then begin stepping through the code until the error is found.

A method of eliminating FSFILTER as the component with the problem is to set up a test case that is executed from the diskette. This way, you can execute a VM Start session without installing FSFILTER. If the problem still occurs, then FSFILTER is not the cause of the problem.

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