When we enter protected mode, with the far jump still in big real mode, the JMP instruction not only needs the 0x66 prefix (for 32-bit operand size), but also the 0x67 prefix (for 32-bit address size). Use the a32 nasm modifier to enforce this.
This bug breaks S3 resume in the Ia32 + SMM_REQUIRE build of OVMF. Cc: Liming Gao <liming....@intel.com> Cc: Jordan Justen <jordan.l.jus...@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <ler...@redhat.com> --- UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/MpFuncs.nasm | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/MpFuncs.nasm b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/MpFuncs.nasm index 97cdb4cc9309..f7cdcce9a7b3 100644 --- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/MpFuncs.nasm +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/MpFuncs.nasm @@ -77,7 +77,7 @@ o32 lidt [cs:si] FLAT32_JUMP: - jmp dword 0x20:0x0 +a32 jmp dword 0x20:0x0 BITS 32 PMODE_ENTRY: ; protected mode entry point -- 1.8.3.1 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
