@zir_blazer
The issue described on the above paper is relative to the OVMF video driver implementation.
On legacy hardware and IRQ the INT 10 (Video Driver) is used to retrieve the VESA_BIOS_EXTENSIONS (VBE) function.
The VBE information block allow to determine the capabilities supported by the display adapter.
A Compatibility Support Module (CSM) is not a requirement for the WINDOWS 7 EFI installer.
A functional Graphics Output Protocol (GOP) produced by an EFI video driver IS.
You are completely wrong on that. CSM being needed to install Windows 7 is a rather well known requeriment:
https://support.microsoft.com/en-us/help…-on-surface-pro
https://docs.microsoft.com/en-us/previou…rectedfrom=MSDN
The whole point is that you CANNOT run Windows 7 in pure UEFI mode, be it either TianoCore/OVMF for Virtual Machines or native use cases like UEFI Class 3 Devices (Or for anyone that disables CSM), since Windows goes nuts due to the lack of a INT10 handler, which is the reason why you require CSM enabled and a VBIOS. The VgaShim is pretty much a small UEFI Driver that provides the INT10 interface that Windows 7 expects in an UEFI only environment. And while it was developed for Virtual Machine use cases, some people did ports intended to run in native, like this one, which is an UEFI executable that has to be loaded before Windows Boot Managers: https://github.com/driver1998/VgaShim
Note that the only W7 component that requires the INT10 handler appear to be the Boot Loader. I have been reading that some people replaces it with the W10 one or some hacks like that, and it seem to work. But it doesn’t work out-of-the-box.