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Refine the comments for BiosVideo thunk driver.

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git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@7738 6f19259b-4bc3-4df7-8a09-765794883524
This commit is contained in:
klu2
2009-03-01 07:12:53 +00:00
parent 0d92cdc200
commit f1294e4a56
3 changed files with 586 additions and 876 deletions
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97
DuetPkg/BiosVideoThunkDxe/LegacyBiosThunk.c
View File

@@ -1,13 +1,29 @@
/** @file
Provide legacy thunk interface for accessing Bios Video Rom.
Copyright (c) 2006 - 2007, Intel Corporation
All rights reserved. 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 "BiosVideo.h"
#define EFI_CPU_EFLAGS_IF 0x200
THUNK_CONTEXT mThunkContext;
/**
Initialize legacy environment for BIOS INI caller.
@param ThunkContext the instance pointer of THUNK_CONTEXT
**/
VOID
InitializeBiosIntCaller (
IN BIOS_VIDEO_DEV *BiosDev
THUNK_CONTEXT *ThunkContext
)
{
EFI_STATUS Status;
@@ -29,32 +45,27 @@ InitializeBiosIntCaller (
);
ASSERT_EFI_ERROR (Status);
mThunkContext.RealModeBuffer = (VOID*)(UINTN)LegacyRegionBase;
mThunkContext.RealModeBufferSize = EFI_PAGES_TO_SIZE (RealModeBufferSize);
mThunkContext.ThunkAttributes = 3;
AsmPrepareThunk16(&mThunkContext);
ThunkContext->RealModeBuffer = (VOID*)(UINTN)LegacyRegionBase;
ThunkContext->RealModeBufferSize = EFI_PAGES_TO_SIZE (RealModeBufferSize);
ThunkContext->ThunkAttributes = 3;
AsmPrepareThunk16(ThunkContext);
}
/**
Initialize interrupt redirection code and entries, because
IDT Vectors 0x68-0x6f must be redirected to IDT Vectors 0x08-0x0f.
Or the interrupt will lost when we do thunk.
NOTE: We do not reset 8259 vector base, because it will cause pending
interrupt lost.
@param Legacy8259 Instance pointer for EFI_LEGACY_8259_PROTOCOL.
**/
VOID
InitializeInterruptRedirection (
IN BIOS_VIDEO_DEV *BiosDev
IN EFI_LEGACY_8259_PROTOCOL *Legacy8259
)
/*++
Routine Description:
Initialize interrupt redirection code and entries, because
IDT Vectors 0x68-0x6f must be redirected to IDT Vectors 0x08-0x0f.
Or the interrupt will lost when we do thunk.
NOTE: We do not reset 8259 vector base, because it will cause pending
interrupt lost.
Arguments:
NONE
Returns:
NONE
--*/
{
EFI_STATUS Status;
EFI_PHYSICAL_ADDRESS LegacyRegionBase;
@@ -94,7 +105,7 @@ InitializeInterruptRedirection (
//
// Get VectorBase, it should be 0x68
//
Status = BiosDev->Legacy8259->GetVector (BiosDev->Legacy8259, Efi8259Irq0, &ProtectedModeBaseVector);
Status = Legacy8259->GetVector (Legacy8259, Efi8259Irq0, &ProtectedModeBaseVector);
ASSERT_EFI_ERROR (Status);
//
@@ -108,6 +119,19 @@ InitializeInterruptRedirection (
return ;
}
/**
Thunk to 16-bit real mode and execute a software interrupt with a vector
of BiosInt. Regs will contain the 16-bit register context on entry and
exit.
@param This Protocol instance pointer.
@param BiosInt Processor interrupt vector to invoke
@param Reg Register contexted passed into (and returned) from thunk to 16-bit mode
@retval TRUE Thunk completed, and there were no BIOS errors in the target code.
See Regs for status.
@retval FALSE There was a BIOS erro in the target code.
**/
BOOLEAN
EFIAPI
LegacyBiosInt86 (
@@ -115,25 +139,6 @@ LegacyBiosInt86 (
IN UINT8 BiosInt,
IN EFI_IA32_REGISTER_SET *Regs
)
/*++
Routine Description:
Thunk to 16-bit real mode and execute a software interrupt with a vector
of BiosInt. Regs will contain the 16-bit register context on entry and
exit.
Arguments:
This - Protocol instance pointer.
BiosInt - Processor interrupt vector to invoke
Reg - Register contexted passed into (and returned) from thunk to
16-bit mode
Returns:
FALSE - Thunk completed, and there were no BIOS errors in the target code.
See Regs for status.
TRUE - There was a BIOS erro in the target code.
--*/
{
UINTN Status;
UINTN Eflags;
@@ -178,7 +183,7 @@ LegacyBiosInt86 (
Status = BiosDev->Legacy8259->SetMode (BiosDev->Legacy8259, Efi8259LegacyMode, NULL, NULL);
ASSERT_EFI_ERROR (Status);
Stack16 = (UINT16 *)((UINT8 *) mThunkContext.RealModeBuffer + mThunkContext.RealModeBufferSize - sizeof (UINT16));
Stack16 = (UINT16 *)((UINT8 *) BiosDev->ThunkContext->RealModeBuffer + BiosDev->ThunkContext->RealModeBufferSize - sizeof (UINT16));
Stack16 -= sizeof (ThunkRegSet.E.EFLAGS) / sizeof (UINT16);
CopyMem (Stack16, &ThunkRegSet.E.EFLAGS, sizeof (ThunkRegSet.E.EFLAGS));
@@ -186,8 +191,8 @@ LegacyBiosInt86 (
ThunkRegSet.E.ESP = (UINT16) (UINTN) Stack16;
ThunkRegSet.E.Eip = (UINT16)((UINT32 *)NULL)[BiosInt];
ThunkRegSet.E.CS = (UINT16)(((UINT32 *)NULL)[BiosInt] >> 16);
mThunkContext.RealModeState = &ThunkRegSet;
AsmThunk16 (&mThunkContext);
BiosDev->ThunkContext->RealModeState = &ThunkRegSet;
AsmThunk16 (BiosDev->ThunkContext);
//
// Restore protected mode interrupt state