When running a shell app twice, I ran into an interesting problem: global variables that had initializers were not initialized to the defaults specified in the source. Running the same shell app under the old NT32 seems to work. It turns out that the shell app was not being reloaded, but rather being relaunched. I deduced this from the following behavior:

 

1.	The value of the global variables was the same as the last known value from the previous invocation.
2.	The following line in WinHost.c was returning the exact same value for the DLL being loaded

Library = LoadLibraryEx (DllFileName, NULL, DONT_RESOLVE_DLL_REFERENCES); (around line 901)

3.	The corresponding code in Nt32’s PeCoffExtractionLib had the following lines in PeCoffLoaderUnloadImageExtraAction

  VOID *ModHandle;

 

  ASSERT (ImageContext != NULL);

  ModHandle = RemoveModeHandle (ImageContext);

  if (ModHandle != NULL) {

    mWinNt->FreeLibrary (ModHandle);

  }

 

However, the same function in EmulatorPkg’s WinHost.c has:

 

ASSERT (ImageContext != NULL);

 

So it appears that the DLL is never being unloaded and the subsequent invocation of the shell app uses the same instance of the DLL, leaving the global variables with the previous values. There are two related functions: AddModHandle and RemoveModHandle.

 

Am I missing something? Or heading in the right direction? 

 

Thanks,

Tim

 

From: devel@edk2.groups.io <devel@edk2.groups.io> 
Sent: Saturday, August 17, 2019 6:30 PM
To: devel@edk2.groups.io
Subject: [edk2-devel] Upcoming Event: TianoCore Design Meeting - APAC/NAMO - Thu, 08/22/2019 6:30pm-7:30pm #cal-reminder

 

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