OvmfPkg: QemuVideoDxe: Int10h stub for Windows 7 & 2008 (stdvga, QXL)
The Windows 2008 R2 SP1 (and Windows 7) UEFI guest's default video driver
dereferences the real mode Int10h vector, loads the pointed-to handler
code, and executes what it thinks to be VGA BIOS services in an internal
real-mode emulator. Consequently, video mode switching doesn't work in
Windows 2008 R2 SP1 when it runs on the pure UEFI build of OVMF, making
the guest uninstallable.
This patch adds a VGABIOS "shim" to QemuVideoDxe. For the first stdvga or
QXL card bound, an extremely stripped down VGABIOS imitation is installed
in the C segment. It provides a real implementation for the few services
that are in fact necessary for the win2k8r2sp1 UEFI guest, plus some fakes
that the guest invokes but whose effect is not important.
The C segment is not present in the UEFI memory map prepared by OVMF. We
never add memory space that would cover it (either in PEI, in the form of
memory resource descriptor HOBs, or in DXE, via gDS->AddMemorySpace()).
This way the handler body is invisible to all non-buggy UEFI guests, and
the rest of edk2.
The Int10h real-mode IVT entry is covered with a Boot Services Code page,
making that too unaccessible to the rest of edk2. (Thus UEFI guest OSes
different from the Windows 2008 family can reclaim the page. The Windows
2008 family accesses the page at zero regardless of the allocation type.)
The patch is the result of collaboration:
Initial proof of concept IVT entry installation and handler skeleton (in
NASM) by Jordan Justen.
Service tracing and implementation, data collection/analysis, and C coding
by yours truly.
Last minute changes by Gerd Hoffmann:
- Use OEM mode number (0xf1) instead of standard 800x600 mode (0x143). The
resolution of the OEM mode (0xf1) is not standardized; the guest can't
expect anything from it in advance.
- Use 1024x768 rather than 800x600 for more convenience in the Windows
2008 R2 SP1 guest during OS installation, and after normal boot until
the QXL XDDM guest driver is installed.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15540 6f19259b-4bc3-4df7-8a09-765794883524
2014-05-20 18:33:00 +02:00
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#!/bin/sh
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###
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# @file
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# Shell script to assemble and dump the fake Int10h handler from NASM source to
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# a C array.
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#
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# Copyright (C) 2014, Red Hat, Inc.
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# Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.<BR>
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#
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2019-04-04 01:06:33 +02:00
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# SPDX-License-Identifier: BSD-2-Clause-Patent
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OvmfPkg: QemuVideoDxe: Int10h stub for Windows 7 & 2008 (stdvga, QXL)
The Windows 2008 R2 SP1 (and Windows 7) UEFI guest's default video driver
dereferences the real mode Int10h vector, loads the pointed-to handler
code, and executes what it thinks to be VGA BIOS services in an internal
real-mode emulator. Consequently, video mode switching doesn't work in
Windows 2008 R2 SP1 when it runs on the pure UEFI build of OVMF, making
the guest uninstallable.
This patch adds a VGABIOS "shim" to QemuVideoDxe. For the first stdvga or
QXL card bound, an extremely stripped down VGABIOS imitation is installed
in the C segment. It provides a real implementation for the few services
that are in fact necessary for the win2k8r2sp1 UEFI guest, plus some fakes
that the guest invokes but whose effect is not important.
The C segment is not present in the UEFI memory map prepared by OVMF. We
never add memory space that would cover it (either in PEI, in the form of
memory resource descriptor HOBs, or in DXE, via gDS->AddMemorySpace()).
This way the handler body is invisible to all non-buggy UEFI guests, and
the rest of edk2.
The Int10h real-mode IVT entry is covered with a Boot Services Code page,
making that too unaccessible to the rest of edk2. (Thus UEFI guest OSes
different from the Windows 2008 family can reclaim the page. The Windows
2008 family accesses the page at zero regardless of the allocation type.)
The patch is the result of collaboration:
Initial proof of concept IVT entry installation and handler skeleton (in
NASM) by Jordan Justen.
Service tracing and implementation, data collection/analysis, and C coding
by yours truly.
Last minute changes by Gerd Hoffmann:
- Use OEM mode number (0xf1) instead of standard 800x600 mode (0x143). The
resolution of the OEM mode (0xf1) is not standardized; the guest can't
expect anything from it in advance.
- Use 1024x768 rather than 800x600 for more convenience in the Windows
2008 R2 SP1 guest during OS installation, and after normal boot until
the QXL XDDM guest driver is installed.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15540 6f19259b-4bc3-4df7-8a09-765794883524
2014-05-20 18:33:00 +02:00
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#
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###
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set -e -u
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STEM=$(dirname -- "$0")/$(basename -- "$0" .sh)
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#
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# Install exit handler -- remove temporary files.
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#
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exit_handler()
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{
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rm -f -- "$STEM".bin "$STEM".disasm "$STEM".offsets "$STEM".insns \
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"$STEM".bytes
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}
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trap exit_handler EXIT
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#
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# Assemble the source file.
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#
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nasm -o "$STEM".bin -- "$STEM".asm
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#
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# Disassemble it, in order to get a binary dump associated with the source.
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# (ndisasm doesn't recognize the "--" end-of-options delimiter.)
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#
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ndisasm "$STEM".bin >"$STEM".disasm
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#
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# Create three files, each with one column of the disassembly.
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#
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# The first column contains the offsets, and it starts the comment.
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#
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cut -c 1-8 -- "$STEM".disasm \
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| sed -e 's,^, /* ,' >"$STEM".offsets
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#
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# The second column contains the assembly-language instructions, and it closes
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# the comment. We first pad it to 30 characters.
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#
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cut -c 29- -- "$STEM".disasm \
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| sed -e 's,$, ,' \
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-e 's,^\(.\{30\}\).*$,\1 */,' >"$STEM".insns
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#
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# The third column contains the bytes corresponding to the instruction,
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# represented as C integer constants. First strip trailing whitespace from the
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# middle column of the input disassembly, then process pairs of nibbles.
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#
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cut -c 11-28 -- "$STEM".disasm \
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| sed -e 's, \+$,,' -e 's/\(..\)/ 0x\1,/g' >"$STEM".bytes
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#
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# Write the output file, recombining the columns. The output should have CRLF
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# line endings.
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#
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{
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printf '//\n'
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printf '// THIS FILE WAS GENERATED BY "%s". DO NOT EDIT.\n' \
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"$(basename -- "$0")"
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printf '//\n'
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printf '#ifndef _VBE_SHIM_H_\n'
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printf '#define _VBE_SHIM_H_\n'
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printf 'STATIC CONST UINT8 mVbeShim[] = {\n'
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paste -d ' ' -- "$STEM".offsets "$STEM".insns "$STEM".bytes
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printf '};\n'
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printf '#endif\n'
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} \
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| unix2dos >"$STEM".h
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