SCSIPORT debugging

Microsoft provides useful extensions for debugging SCSIPORT drivers in WinDbg. But with some versions of scsiport.sys, the symbol files don’t contain type information. This produces fun errors like the following.

kd> !scsikd.scsiext 8a392a38
*************************************************************************
***                                                                   ***
***                                                                   ***
***    Your debugger is not using the correct symbols                 ***
***                                                                   ***
***    In order for this command to work properly, your symbol path   ***
***    must point to .pdb files that have full type information.      ***
***                                                                   ***
***    Certain .pdb files (such as the public OS symbols) do not      ***
***    contain the required information.  Contact the group that      ***
***    provided you with these symbols if you need this command to    ***
***    work.                                                          ***
***                                                                   ***
***    Type referenced: scsiport!_DEVICE_OBJECT                       ***
***                                                                   ***
*************************************************************************
scsikd error (3): ...\storage\kdext\scsikd\scsikd.c @ line 188

This makes the common task of getting your device extension object very daunting. After some digging, I came up with this code to at least get my device extension object from SCSIPORT’s device extension object.

!drvobj mydriver
* get relevant DevObj
!devobj <devobj>
* get DevExt
dt mydriver!MY_DEVICE_EXTENSION poi(<DevExt> + b4)

I’ve only tried it on Windows XP SP3. The offset may be different with other configurations. Anyone knows a better way around this? Preferable method would naturally be making scsikd work.