windows 8.1 garbled hdmi display output

[acoul]

Operating system

Windows 8.1 x64 6.3.9600.16384

Issue description

windows 8.1 works fine with EfiGuard. under special conditions, there is a problem though

Steps to reproduce

1. use a Ventoy usb disk
2. load GrubFM iso
3. navigate & load EfiGuardDxe.efi as device driver
4. while within GrubFM navigate & load windows 8.1

with the above steps, the display output is garbled, distorted and non-functional

not using Ventoy on the above steps, the display output works fine but the resolution is not adjusted to the max supported by that of the display

I've tested this on both an Intel N100 & a ryzen 4500U

there are no display drivers for those systems for windows 8.1, thereof the basic display driver is used

Ventoy does some alchemy and without EfiGuard both systems can work fine utilizing the maximum display resolution

not using Ventoy, with or without EfiGuard, both systems work fine, but on the Intel N100 the max resolution is 1024x768 while on the ryzen 4500U is 800x600

Logs

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Attachments

[acoul]

same behavior on a Ryzen 5 1600AF with a Radeon HD 8490 (CSM disabled)

the way to have the basic display driver provide max resolution on win8 (for me) is to use Ventoy to load grubfm_multiarch.iso then load EfiGuardDxe.efi as device driver and then by the F3 key choosing the appropriate OS to boot

the above procedure results though in a distorted display even when hitting F8 key when booting windows that gives a text menu with boot choices

in GrubFM, if instead of loading EfiGuardDxe.efi as device driver I choose Loader.efi loaded as application, everything works fine

I finally followed the steps described here to load the driver automatically at each boot with the command:
bcfg driver add 0 FS1:\EFI\Boot\EfiGuardDxe.efi "EfiGuardDxe"

thereof, skipping Ventoy & GrubFM altogether and booting directly to windows manager from the bios menu with the same garbled display output

Edit: with the hdmi display output garbled, it's possible to work remotely through vnc, thereof the issue is located at the hdmi output