Re: [Patch] SourceLevelDebugPkg/SecPeiDebugAgentLib: Fix duplicate symbol

[Laszlo Ersek <lersek@redhat.com>]

On 05/25/17 21:57, Kinney, Michael D wrote:
> Laszlo,
> 
> I have the same concern on final image sizes.  I have done some
> evaluation:
> 
> GCC5 OVMF X64 DEBUG without -whole-archive 
> ==========================================
> FV Space Information
> SECFV [19%Full] 212992 total, 42000 used, 170992 free
> FVMAIN_COMPACT [33%Full] 3440640 total, 1162760 used, 2277880 free
> DXEFV [38%Full] 10485760 total, 4024024 used, 6461736 free
> PEIFV [19%Full] 917504 total, 180648 used, 736856 free
> Total used = 5409432
> 
> GCC5 OVMF X64 DEBUG with -whole-archive 
> =======================================
> FV Space Information
> SECFV [19%Full] 212992 total, 41936 used, 171056 free
> FVMAIN_COMPACT [33%Full] 3440640 total, 1158304 used, 2282336 free
> DXEFV [38%Full] 10485760 total, 4029656 used, 6456104 free
> PEIFV [19%Full] 917504 total, 181352 used, 736152 free
> Total used = 5411248
> 
> Total used difference = 1816 bytes larger with -whole-archive
> 
> I was also able to do a MSFT VS2015 build with /WHOLEARCHIVE set
> and it also catches the same duplicate symbol error now.
> 
> error C2220: warning treated as error - no 'executable' file generated
> warning C4744: 'mMemoryDiscoveredNotifyList' has different type in 'd:\work\github\tianocore\edk2\mdemodulepkg\core\dxeiplpeim\dxeload.c' and 'd:\work\github\tianocore\edk2\sourceleveldebugpkg\library\debugagent\secpeidebugagent\secpeidebugagentlib.c': 'struct (12 bytes)' and 'array (12 bytes)'
> DxeIpl.lib(DxeLoad.obj) : error LNK2005: _mMemoryDiscoveredNotifyList already defined in SecPeiDebugAgentLib.lib(SecPeiDebugAgentLib.obj)
> d:\work\github\tianocore\edk2\Build\OvmfIa32\DEBUG_VS2015x86\IA32\MdeModulePkg\Core\DxeIplPeim\DxeIpl\DEBUG\DxeIpl.dll : fatal error LNK1169: one or more multiply defined symbols found
> 
> VS2015 OVMF X64 DEBUG without /WHOLEARCHIVE 
> ===========================================
> FV Space Information
> SECFV [22%Full] 212992 total, 48560 used, 164432 free
> FVMAIN_COMPACT [33%Full] 3440640 total, 1147464 used, 2293176 free
> DXEFV [39%Full] 10485760 total, 4163888 used, 6321872 free
> PEIFV [22%Full] 917504 total, 204840 used, 712664 free
> Total used = 5564752
> 
> 
> VS2015 OVMF X64 DEBUG with /WHOLEARCHIVE 
> ===========================================
> FV Space Information
> SECFV [23%Full] 212992 total, 50384 used, 162608 free
> FVMAIN_COMPACT [33%Full] 3440640 total, 1147424 used, 2293216 free
> DXEFV [42%Full] 10485760 total, 4422992 used, 6062768 free
> PEIFV [27%Full] 917504 total, 255528 used, 661976 free
> Total used = 5875338
> 
> Total used difference = 310586 bytes larger with /WHOLEARCHIVE
> 
> For tool chains that do have size impacts, one option is to
> have a "test" build that enables the linker flags to detect
> duplicate symbols.  For example the following could be added
> to a DSC file.  May want to disable GenFds stage when doing
> this type of build.
> 
> [BuildOptions]
> !ifdef $(DETECT_DUPLICATE_SYMBOLS)
>   MSFT:*_VS2015_*_DLINK_FLAGS = /WHOLEARCHIVE
> !endif

Thank you (again) for the research! Looks like the gcc size impact is
friendly enough to keep --whole-archive enabled at all times (possibly
due to the --gc-sections flag mentioned by Ard, which we already have
enabled).

The VS2015 impact is really large however.

I was hoping we could add these flags to
"BaseTools/Conf/tools_def.template", regardless of platform DSC. (If the
flag is non-default, and/or it's platform-dependent, then it will almost
never be used, most likely.) But the VS2015 size increase really
precludes /WHOLEARCHIVE (for the MSFT family) from "tools_def.template".

Would it be acceptable to add --whole-archive to "tools_def.template"
only for GCC? After all, at the moment only XCODE*/XCLANG have "-all_load".

Thanks,
Laszlo