id = 2231
title = "GNOME/Mutter - Wayland Fractional Scaling Breaks VM Resolution"
state = "opened"
created_at = "2024-03-19T22:12:18.435Z"
closed_at = "n/a"
labels = ["GUI"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/2231"
host-os = "Fedora 39"
host-arch = "x86"
qemu-version = "8.1.3 (qemu-8.1.3.4.fc39)"
guest-os = "any (Tested Fedora 38,39, GNOME OS Nightly, and Windows 10,11)"
guest-arch = "x86"
description = """VMs are rendered at a higher resolution than the pixel count of their window, seemingly because mutter is upscaling for fractional scaling."""
reproduce = """1. Enable GNOME Mutter experimental fractional scaling
2. Launch VM"""
additional = """This only occurs when wayland fractional scaling is enabled, not when text is scaled. Since GNOME/mutter accomplishes fractional scaling by upscaling, I think the VM is being told its window has a higher resolution than it actually has, so it is rendering the VM at a higher resolution, which is then displayed at the display's real resolution.

In the screenshot below, my resolution is 2256 x 1504 and I have set fractional scaling to 125%. It is worth noting (2256 / 1.25) / 3606 is approximately 0.5.

![image](/uploads/0014f068f6491175c00449093c40cd8c/image.png)

I apologize if the report is unsatisfactory. I will provide more detail if instructed. I tried reporting to GNOME Boxes and Virt-manager, which both use QEMU, but it seems the problem is upstream."""