Specifications

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3.3.3.2 Legacy Soft SMI
Summary
SMM code is provided from the same IBV as the Compatibility16 and the Legacy BIOS
Platform Protocol code. The soft SMI structures in
SMM_TABLE (defined in
Compatibility16PrepareToBoot()) are meant to establish a common standard
but are not required to be implemented by the IBV. If the structures are used, then the
recommended interface between the SMM code and Compatibility16 code is defined
below.
Input Registers
EAX, AX, AL = SmmTable.SmmEntry.SmmData (32-bit, 16-bit, or 8-bit)
EDX, DX, DL = SmmTable.SmmEntry.SmmPort (32-bit, 16-bit, or 8-bit)
ESI = Pointer to
EFI_DWORD_REGS
Related Definitions
EFI_DWORD_REGS is defined in the EFI_LEGACY_BIOS_PROTOCOL.Int86() function.