Monday, November 27, 2017

Windbg Useless Mex Rule "Issue 9912"

SCENARIO

If you are using Windbg to view a crash dump and you are using the mex extension, then you might recieved the following when running the known issue checker (!kic):

0: kd> !kic
[Rule 9912] Found issue from rule 9912!
[Rule 9912] Additional Data
[Rule 9912]  ---------------------
[Rule 9912] mex has no win32k export
[Rule 9912]
[Rule 9912]  ---------------------
[Rule 9912]
Stats:
Rules Ran: 92 Success: 76 Failed: 0 Skipped: 16
Number of Issues Found: 1
Total Number of Rules: 189
Scan Ended:  11/16/2017 10:52:50 AM (00:10:19.0159146)

I had a 2016 server that was bug-checking every time we ran robocopy to copy large amounts of files to it.

Using the debugger with the mex extension, you can run !kic and sometimes it will find a known issue. In my case, rule 9912 fired. However, no win32k export was found.

So I contacted Microsoft regarding this rule and one of the guys who works on the mex extension told me that this rule looks for oddities within open sessions.  But he said that this rule should be ignored.

So if you get this rule from the known issue checker, you should ignore it and continue searching through the crash dump for the cause of the issue.

Don't let this dissuade you from using the mex extension, it's a great extension!

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