d057d8c4e9
Legacy has to access interrupt vector, BDA, etc. located in memory between 0-4095. To allow as much code as possible to be monitored by NULL pointer detection, we add code to temporarily disable this feature right before those memory access and enable it again afterwards. Cc: Star Zeng <star.zeng@intel.com> Cc: Eric Dong <eric.dong@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Michael Kinney <michael.d.kinney@intel.com> Cc: Ayellet Wolman <ayellet.wolman@intel.com> Suggested-by: Ayellet Wolman <ayellet.wolman@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Jian J Wang <jian.j.wang@intel.com> Reviewed-by: Jiewen Yao <jiewen.yao@intel.com> Reviewed-by: Star Zeng <star.zeng@intel.com>
71 lines
1.8 KiB
C
71 lines
1.8 KiB
C
/** @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>
|
|
|
|
This program and the accompanying materials
|
|
are licensed and made available under the terms and conditions
|
|
of the BSD License which accompanies this distribution. The
|
|
full text of the license may be found at
|
|
http://opensource.org/licenses/bsd-license.php
|
|
|
|
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
|
|
|
|
**/
|
|
|
|
#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;
|
|
|
|
DisableNullDetection ();
|
|
|
|
Bda = (BDA_STRUC *) ((UINTN) 0x400);
|
|
Ebda = (UINT8 *) ((UINTN) 0x9fc00);
|
|
|
|
ZeroMem (Bda, 0x100);
|
|
ZeroMem (Ebda, 0x400);
|
|
//
|
|
// 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;
|
|
|
|
*Ebda = 0x01;
|
|
|
|
EnableNullDetection ();
|
|
|
|
return EFI_SUCCESS;
|
|
}
|