Question about building iPXE with named configuration

[NiKiZe]

Never change the original config/*.h
instead add new files to config/local/*.h which you add the specific changes to.
So yes always keep originals untouched.

If you are certain that there is features that you want to remove from the default build then #undef those yes
However do not create copies of original files and just undef anything that you don't think that you need.

Only undef if you know that specific setting is causing you issues.
Only define if you know that specific setting is needed for your uses.

But I would like to back up a little... Could you share the specific configs you have? And especially the reason for why you need to have one for PCBIOS and one for EFI ?
And if we see that you really do need different configs here than we can jump into the "named configs" part, but for now try to just use config/local instead.