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/** @file
This code fills in BDA (0x400) and EBDA (pointed to by 0x4xx)
information. There is support for doing initializeation before
Legacy16 is loaded and before a legacy boot is attempted.
Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "LegacyBiosInterface.h"
/**
Fill in the standard BDA and EBDA stuff before Legacy16 load
@param Private Legacy BIOS Instance data
@retval EFI_SUCCESS It should always work.
**/
EFI_STATUS
LegacyBiosInitBda (
IN LEGACY_BIOS_INSTANCE *Private
)
{
BDA_STRUC *Bda;
UINT8 *Ebda;
Bda = (BDA_STRUC *)((UINTN)0x400);
Ebda = (UINT8 *)((UINTN)0x9fc00);
ACCESS_PAGE0_CODE (
ZeroMem (Bda, 0x100);
//
// 640k-1k for EBDA
//
Bda->MemSize = 0x27f;
Bda->KeyHead = 0x1e;
Bda->KeyTail = 0x1e;
Bda->FloppyData = 0x00;
Bda->FloppyTimeout = 0xff;
Bda->KeyStart = 0x001E;
Bda->KeyEnd = 0x003E;
Bda->KeyboardStatus = 0x10;
Bda->Ebda = 0x9fc0;
//
// Move LPT time out here and zero out LPT4 since some SCSI OPROMS
// use this as scratch pad (LPT4 is Reserved)
//
Bda->Lpt1_2Timeout = 0x1414;
Bda->Lpt3_4Timeout = 0x1400;
);
ZeroMem (Ebda, 0x400);
*Ebda = 0x01;
return EFI_SUCCESS;
}
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