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SctPkg: Replace global -mabi=ms with EFIAPI macro for GCC IA32/X64 - #358
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June 12, 2026 08:56
REF: tianocore#285 The edk2 community prefers adding the missing EFIAPI annotation to each public interface over using '-mabi=ms' as a global declaration, so that only functions that genuinely cross the UEFI ABI boundary carry the Microsoft calling convention, while the rest of the code stays on the host System V ABI. Following that direction, replace the global '-mabi=ms' compiler flag with an explicit EFIAPI macro definition '-DEFIAPI=__attribute__((ms_abi))' for GCC IA32 and X64 toolchains. This makes the ABI boundary explicit at the declaration site instead of implicit at the build-system level. Signed-off-by: Richard Lyu <richard.lyu@suse.com>
Annotate the public print function declarations (SctPrintAt, SctPrint, SctAPrint, SctSPrint, SctVSPrint, SctAVSPrint, SctASPrint, SctPoolPrint, SctCatPrint) with EFIAPI to match their definitions in SctLib/Print.c, ensuring a consistent calling convention across the call sites once EFIAPI is explicitly defined for GCC IA32/X64. Signed-off-by: Richard Lyu <richard.lyu@suse.com>
With -mabi=ms removed and EFIAPI explicitly defined for GCC IA32/X64, the va_list calling chain in SctLib/Print.c requires careful handling to keep a consistent ABI across the entire print pipeline: - SCT_PRINT_STATE.Output and .SetAttr changed to EFIAPI function pointer types to match UEFI EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL - Type casts for OutputString and SetAttribute updated to include EFIAPI - All variadic functions (SctPrint, SctSPrint, SctPoolPrint, etc.) and VA_LIST consumers (SctVSPrint, _IPrint, _PoolCatPrint, etc.) annotated with EFIAPI to ensure consistent va_list ABI throughout the call chain - All static internal helpers that participate in the print pipeline (_Print, PFLUSH, PPUTC, PITEM, PGETC, PSETATTR, etc.) annotated with EFIAPI accordingly Signed-off-by: Richard Lyu <richard.lyu@suse.com>
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Thank you for the updates.
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| # GCC:*_*_IA32_CC_FLAGS = -D EFI32 $(GCC_VER_MACRO) -ffreestanding -nostdinc -nostdlib -Wno-error -mno-red-zone -Wno-address -mno-stack-arg-probe "-DEFIAPI=__attribute__((ms_abi))" -m32 -mabi=ms -D MDE_CPU_X32 | ||
| GCC:*_*_IA32_CC_FLAGS = -D EFIX64 $(GCC_VER_MACRO) -Wno-error -mabi=ms | ||
| GCC:*_*_IA32_CC_FLAGS = -D EFIX64 $(GCC_VER_MACRO) -Wno-error "-DEFIAPI=__attribute__((ms_abi))" |
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Is this change tested for all functions in a edk2-test run?
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Yes, I ran a full SCT run. All test suites were executed, 7079 cases total, on
OVMF/QEMU, and the results are identical before and after the patch. This change
is expected to affect the x86 platform only.
| without patch | with patch | |
|---|---|---|
| Total | 7079 | 7079 |
| Passed | 7047 | 7047 |
| Failed | 32 | 32 |
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@edhay When can we expect this to be merged? Currently, this should only affect IA32/X64 GCC builds. |
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Summary
REF: #285
The edk2 community prefers annotating public interfaces with
EFIAPIover forcing the Microsoft x64 calling convention globally via
-mabi=ms. The global flag obscures which symbols actually cross theUEFI ABI boundary and silently changes the calling convention of
internal helpers that should follow the host System V ABI.
This series replaces the global
-mabi=msflag for GCC IA32/X64 withan explicit
EFIAPImacro, then annotates the SctLib print pipelineso the
va_listABI stays consistent end-to-end.Changes
SctPkg/UEFI— Replace-mabi=mswith-DEFIAPI=__attribute__((ms_abi))for the GCC IA32/X64 toolchainsin
UEFI_SCT.dsc.SctPkg/Include— AddEFIAPIto the public print functiondeclarations (
SctPrint,SctSPrint,SctVSPrint, etc.) so callsites pick up the correct calling convention.
SctPkg/Library/SctLib— AddEFIAPIto print functiondefinitions, internal helpers, and
VA_LISTconsumers so theva_listABI is consistent through the entire print pipeline.