UEFI: Difference between revisions

 

==== GNU-EFI and GCC ====

cdecl is the standard calling convention used by GCC, so no special attributes or modifiers are needed for writing the main entry point or calling UEFI functions in an x86 UEFI application developed with GNU-EFI. For x86-64, however, the entry point function must be declared with the "___attribute___((ms_abi))" modifier and all calls to UEFI-provided functions must be made through the "uefi_call_wrapper" thunk. This thunk is called with cdecl, but then translates to the Microsoft x86-64 calling convention before calling the requested UEFI function. This is necessary because older releases of GCC do not support specifying calling conventions for function pointers.