2ea3576e16
Current implementation uses following two methods
EnableNullDetection()
DisableNullDetection()
to enable/disable page 0. These two methods will check PCD
PcdNullPointerDetectionPropertyMask to know if the page 0 is disabled or not.
This is due to the fact that old GCD service doesn't provide paging related
attributes of memory block. Since this issue has been fixed, GCD services
can be used to determine the paging status of page 0. This is also make it
possible to just use a new macro
ACCESS_PAGE0_CODE(
<code accessing page 0>
);
to replace above methods to do the same job, which also makes code more
readability.
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
70 lines
1.8 KiB
C
70 lines
1.8 KiB
C
/** @file
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This code fills in BDA (0x400) and EBDA (pointed to by 0x4xx)
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information. There is support for doing initializeation before
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Legacy16 is loaded and before a legacy boot is attempted.
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Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions
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of the BSD License which accompanies this distribution. The
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full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include "LegacyBiosInterface.h"
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/**
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Fill in the standard BDA and EBDA stuff before Legacy16 load
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@param Private Legacy BIOS Instance data
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@retval EFI_SUCCESS It should always work.
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**/
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EFI_STATUS
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LegacyBiosInitBda (
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IN LEGACY_BIOS_INSTANCE *Private
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)
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{
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BDA_STRUC *Bda;
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UINT8 *Ebda;
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Bda = (BDA_STRUC *) ((UINTN) 0x400);
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Ebda = (UINT8 *) ((UINTN) 0x9fc00);
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ACCESS_PAGE0_CODE (
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ZeroMem (Bda, 0x100);
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//
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// 640k-1k for EBDA
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//
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Bda->MemSize = 0x27f;
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Bda->KeyHead = 0x1e;
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Bda->KeyTail = 0x1e;
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Bda->FloppyData = 0x00;
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Bda->FloppyTimeout = 0xff;
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Bda->KeyStart = 0x001E;
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Bda->KeyEnd = 0x003E;
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Bda->KeyboardStatus = 0x10;
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Bda->Ebda = 0x9fc0;
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//
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// Move LPT time out here and zero out LPT4 since some SCSI OPROMS
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// use this as scratch pad (LPT4 is Reserved)
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//
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Bda->Lpt1_2Timeout = 0x1414;
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Bda->Lpt3_4Timeout = 0x1400;
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);
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ZeroMem (Ebda, 0x400);
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*Ebda = 0x01;
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return EFI_SUCCESS;
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}
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