mirror of https://github.com/acidanthera/audk.git
90803342b1
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 |
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| .. | ||
| ComponentName.c | ||
| Driver.c | ||
| DriverSupportedEfiVersion.c | ||
| Gop.c | ||
| Initialize.c | ||
| Qemu.h | ||
| QemuVideoDxe.inf | ||
| VbeShim.asm | ||
| VbeShim.c | ||
| VbeShim.h | ||
| VbeShim.sh | ||