Re: gdb reload-uefi missing EFI_SYSTEM_TABLE_POINTER [was: Source code debugging of OVMF]

[Gary Lin <glin@suse.com>]

On Fri, Apr 20, 2018 at 04:54:06PM +0200, Johannes Swoboda wrote:
> Hello,
> 
> Thank you all for your insights.
> 
> You advised me to use the scripts from [1].
> I did so following this guide [2] (thank you also for putting it back up!),
> with the minor adaptions that I made the script python3-compatible[3], and
> applied the patches mentioned in [2] manually. I assume they failed because
> they could only be applied to older versions of the files to be patched.
> 
> In particular, I added the line DebugPkg/GdbSyms/GdbSyms.inf right below
> line OvmfPkg/PlatformDxe/Platform.inf in line 830 of the vUDK2018 release.
> That makes sense, right?
> 
> The guide looks promising; I think this would give me everything I need.
> However I ran into a problem when executing
> > (gdb) reload-uefi -o
> > ./Build/OvmfX64/DEBUG_GCC5/X64/DebugPkg/GdbSyms/GdbSyms/DEBUG/GdbSyms.dll
> 
> gdb complained:
> > Python Exception <class 'gdb.error'> No type named
> > EFI_SYSTEM_TABLE_POINTER.:
> > Error occurred in Python command: No type named
> > EFI_SYSTEM_TABLE_POINTER.
> 
> The EFI_SYSTEM_TABLE_POINTER is defined in
> [WORKSPACE]/MdeModulePkg/Core/Dxe/Misc/DebugImageInfo.c, so I'm guessing I
> lack that file respectively its corresponding module.
> 
I encountered the issue before and it seems caused by the linker option,
"--whole-archive", which drops the symbols not used.

As a workaround, I add the following lines to Initialize():

  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &ESTP));
  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &EDIITH));
  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &EIDH));
  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &EIOHU));
  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &EIDDE));
  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &EIDCNE));
  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &EIDCRE));
  DEBUG ((DEBUG_VERBOSE, "%a: %llx\n", __FUNCTION__, &EIDCME));

It at least makes the linker believe the symbols are important.
Maybe you can try it.

Cheers,

Gary Lin

> I compiled OVMF with nice OvmfPkg/build.sh -a X64 -n $(getconf
> _NPROCESSORS_ONLN).
> 
> If you could tell me whether my guess make sense and how I would include
> [WORKSPACE]/MdeModulePkg/Core/Dxe/Misc/DebugImageInfo.c, that would be
> great.
> 
> Kind regards,
> Johannes
> 
> [1]: https://github.com/andreiw/andreiw-wip.git
> [2]: https://code.bluestop.org/w/tianocore/debugging-with-gdb/
> [3]: https://github.com/johannesswoboda/andreiw-wip/blob/master/uefi/DebugPkg/Scripts/gdb_uefi.py
> - in case someone else needs it one day
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