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

[Johannes Swoboda <johannes.swoboda@student.tuwien.ac.at>]

Hello again,

Thank you again for taking the time to help me with this.

On 2018-04-20 17:58, Palmer, Thomas wrote:
> Also, did you start qemu with the "-s" option before you started gdb?

Unfortunately, I start qemu with -s -S; then, I attach gdb. I know the 
attaching works because I gdb accepts the continue command which 
instructs qemu to begin execution of the virtual machine.
The source [...]/gdb_uefi.py command seems to work find, but reload-efi 
-o [...]/DEBUG/GdbSyms.dll throws the error "No type named 
EFI_SYSTEM_TABLE_POINTER".

Here is my .gdbinit
set height 0
set architecture i386:x86-64:intel
target remote localhost:1234
source ~/18S/bakk/work/debug_w_andreiw/edk2/DebugPkg/Scripts/gdb_uefi.py
reload-uefi -o 
~/18S/bakk/work/debug_w_andreiw/edk2/Build/OvmfX64/DEBUG_GCC5/X64/DebugPkg/GdbSyms/GdbSyms/DEBUG/GdbSyms.dll

which is executed on gdb startup:
[johannes@johannes-laptop efi_app_only]$ gdb
[...]
The target architecture is assumed to be i386:x86-64:intel
warning: No executable has been specified and target does not support
determining executable automatically.  Try using the "file" command.
0x000000000000fff0 in ?? ()
Python Exception <class 'gdb.error'> No type named 
EFI_SYSTEM_TABLE_POINTER.:
.gdbinit:5: Error in sourced command file:
Error occurred in Python command: No type named 
EFI_SYSTEM_TABLE_POINTER.
(gdb)

Do you have any other suggestions?

Kind regards,
Johannes

> -----Original Message-----
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> On 04/20/18 16:54, Johannes Swoboda wrote:
>> 
>> 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?
> 
> You can add GdbSyms.inf anywhere near the other DXE phase modules.
> Just make sure that you patch the DSC file(s) that you build and run
> afterwards. (I.e., avoid the case where you patch e.g. the X64 DSC but
> then build & boot the IA32 binary.)
Allright, I should be safe there.

>> 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.
> 
> This command will only work after you attach gdb to qemu. In general,
> python extensions for gdb can only look up non-standard typenames etc.
> if gdb is connected to a live image that uses those types.