UEFI: Difference between revisions

Line 118:

A few notes:

* efi.h is included so we can use types like EFI_STATUS, EFI_HANDLE, and EFI_SYSTEM_TABLE.

* When creating a 32-bit UEFI application, EFIAPI is empty; GCC will compile the "efi_main" function using the standard C calling convention. When creating a 64-bit UEFI application, EFIAPI expands to "__attribute__((ms_abi))" and GCC will compile the "efi_main" function using Microsoft's x64 calling convention, as specified by UEFI. Only functions that will be called directly from UEFI (~~i.e.~~ main) need to use the UEFI calling convention.

* When creating a 32-bit UEFI application, EFIAPI is empty; GCC will compile the "efi_main" function using the standard C calling convention. When creating a 64-bit UEFI application, EFIAPI expands to "__attribute__((ms_abi))" and GCC will compile the "efi_main" function using Microsoft's x64 calling convention, as specified by UEFI. Only functions that will be called directly from UEFI (including main, but also callbacks) need to use the UEFI calling convention.

* "InitializeLib" and "Print" are convenience functions provided by libefi.a with prototypes in efilib.h. "InitializeLib" lets libefi.a store a reference to the ImageHandle and SystemTable provided by BIOS. "Print" uses those stored references to print a string by reaching out to UEFI-provided functions in memory. (Later on we will see how to find and call UEFI-provided functions manually.)

@@ Line 118: / Line 118: @@
 A few notes:
 * efi.h is included so we can use types like EFI_STATUS, EFI_HANDLE, and EFI_SYSTEM_TABLE.
-* When creating a 32-bit UEFI application, EFIAPI is empty; GCC will compile the "efi_main" function using the standard C calling convention. When creating a 64-bit UEFI application, EFIAPI expands to "__attribute__((ms_abi))" and GCC will compile the "efi_main" function using Microsoft's x64 calling convention, as specified by UEFI. Only functions that will be called directly from UEFI (i.e. main) need to use the UEFI calling convention.
+* When creating a 32-bit UEFI application, EFIAPI is empty; GCC will compile the "efi_main" function using the standard C calling convention. When creating a 64-bit UEFI application, EFIAPI expands to "__attribute__((ms_abi))" and GCC will compile the "efi_main" function using Microsoft's x64 calling convention, as specified by UEFI. Only functions that will be called directly from UEFI (including main, but also callbacks) need to use the UEFI calling convention.
 * "InitializeLib" and "Print" are convenience functions provided by libefi.a with prototypes in efilib.h. "InitializeLib" lets libefi.a store a reference to the ImageHandle and SystemTable provided by BIOS. "Print" uses those stored references to print a string by reaching out to UEFI-provided functions in memory. (Later on we will see how to find and call UEFI-provided functions manually.)

UEFI: Difference between revisions

Navigation menu

Search