On Nov 29, 2012, at 1:59 AM, nicolas wrote:
> hi, Andrew:
> Thanks for your response!
> So, take ArmPkg\Drivers\CpuDxe as an example:
> In Build\...\CpuDxe\CpuDxe\DEBUG directory, there are 3 files:
> ArmCpuDxe.dll
This is usually the file that was processed to produce ArmCpuDxe.efi PE/COFF
image and it contains the symbols. (not true for VC++ as the symbols end up in
a .pdb file)
> ArmCpuDxe.efi
EFI PE/COFF image
> ArmCpuDxe.map
Human readable map file to show you where stuff got linked
> So, which file is the debug symbol file ?
> It seems uefi code would get the symbol file from ArmCpuDxe.dll .
>
> If i want to use gdb to debug ArmCpuDxe.efi, what is the steps?
add-symbol-file ArmCpuDxe.efi 0xABC00240
Where 0xABC00240 is the load address + sizeof the PE/COFF header.
It is possible to write gdb scripts to load EFI symbols, I'm not sure if one
exists in the edk2?
>
> best wishes,
>
> 发件人: Andrew Fish [mailto:af...@apple.com]
> 发送时间: 2012年11月29日 17:39
> 收件人: edk2-devel@lists.sourceforge.net
> 主题: Re: [edk2] objcopy option "--add-gnu-debuglink"
>
>
> On Nov 29, 2012, at 1:14 AM, nicolas wrote:
>
>
> hi, Andrew:
> Thanks for your response!
> I found gcc has "-g " parameter in tools_def.txt.
> So, it means :
> the produced efi image file has included debug info sections?
>
> -g means produce debug information for the symbols file.
>
>
> And the efi code could retrieve the symbol file from the loaded EFI image?
>
>
> From a PE/COFF point of view the debug information is just the file name of
> the symbol file. So for example this looks like this flag is used to point
> the EFI PE/COFF image at the symbol file.
>
> DEBUG_*_*_OBJCOPY_ADDDEBUGFLAG =
> --add-gnu-debuglink=$(DEBUG_DIR)\$(MODULE_NAME).debug
> RELEASE_*_*_OBJCOPY_ADDDEBUGFLAG =
>
>
>
>
> best wishes,
>
> 发件人: Andrew Fish [mailto:af...@apple.com]
> 发送时间: 2012年11月27日 4:05
> 收件人: edk2-devel@lists.sourceforge.net
> 主题: Re: [edk2] objcopy option "--add-gnu-debuglink"
>
> Nicolas,
>
> I don't know the specific answer for your tools, but I can give you a hint on
> how things work in general.
>
> The general answer is no one actually uses the debug definitions defined in
> COFF or PE/COFF. The PE/COFF file points to another file that contains the
> debug information. For Visual Studio this is a .PDB file, for clang we point
> to a DWARF or DSYM (DWARF + objects).
>
> If you look in the PE/COFF specification
> (http://msdn.microsoft.com/en-us/library/windows/hardware/gg463119.aspx)
> there is something called the Optional Header Data Directories, the term
> optional here is confusing as it is optional for COFF, but required for
> PE/COFF. For most EFI images you will see a Base Relocation Entry, and Debug
> Data Directories entries (assuming it is debug build). The Base Relocation
> Entry contains the fix up info so an image can be loaded at other than its
> linked address (usually zero). The Debug Data Directory entry looks like
> EFI_IMAGE_DEBUG_DIRECTORY_ENTRY
> and it points to a EFI_IMAGE_DEBUG_CODEVIEW_RSDS_ENTRY or one of the other
> types you can find in
> https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/MdePkg/Include/IndustryStandard/PeImage.h.
>
> Basically a EFI_IMAGE_DEBUG_CODEVIEW_RSDS_ENTRY contains the file name of the
> symbols. So loading symbols in EFI usually involves walking the PE/COFF image
> to find the PDB (or other debug file path and name), and this combined with
> the load address of the PE/COFF image is enough to load symbols in a
> debugger. There are library functions that do all this, and you can find them
> by searching for one of the PE/COFF structures I mention in this mail.
>
> On a related side note PE/COFF differs from ELF and Mach-O in that the file
> header is loaded into system memory. Why do I mention this? Well if the build
> system is converting EFL/Mach-O files to PE/COFF you generally have to link
> the ELF/Mach-O file not at zero, but use the size of the PE/COFF header as
> the link address. The reason I mention this is that sometimes when you load
> symbols you need to add back in the size of the PE/COFF header to the PE/COFF
> image load address to get the correct symbol addresses. This shift is only
> required for PE/COFF images that are converted from ELF or Mach-O.
>
> Thanks,
>
> Andrew Fish
>
>
> On Nov 22, 2012, at 9:40 PM, nicolas wrote:
>
>
>
> hi, experts:
> I found a line in tools_def.txt :
> DEBUG_*_*_OBJCOPY_ADDDEBUGFLAG =
> --add-gnu-debuglink=$(DEBUG_DIR)\$(MODULE_NAME).debug
>
> Will it merge debug info file into efi binary?
> Or it will produce a separate debug info file?
>
> best wishes,
>
>
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