id = 1550
title = "Crazy mouse movement when passing `-M pc,vmport=off -accel kvm -vga virtio` at the same time"
state = "opened"
created_at = "2023-03-19T13:52:33.684Z"
closed_at = "n/a"
labels = ["GUI", "device:input"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/1550"
host-os = "Arch Linux"
host-arch = "x86"
qemu-version = "8.0rc0"
guest-os = "Manjaro"
guest-arch = "x86"
description = """The mouse cursor is unusable in an x86 guest (disappears, jumps around like crazy) in a graphical environment when `-M pc,vmport=off -accel kvm -vga virtio` is given at the same time."""
reproduce = """1. Download https://download.manjaro.org/xfce/22.0.5/manjaro-xfce-22.0.5-230316-linux61.iso
2. Start above command
3. Wait until the graphical desktop appears
4. Click inside the window and move the mouse

-> Mouse cursor disappears or jumps around like crazy"""
additional = """If vmport=off is **not** passed, at some point during startup (before graphical login manager appears) the guest switches to use vmmouse from PS/2 mouse. There it also requests usage of absolute input coordinates (VMMOUSE_REQUEST_ABSOLUTE). This code path works normal. Therefore the culprit might be in the guest.

Another way to reproduce the issue is to use -accel whpx under Windows host (no need to pass vmport=off there). It can be observed that the same guest doesn't attempt to switch to vmmouse there, just like passing vmport=off under Linux.

The problem does not exist on Linux host when -accel tcg is used in which case the guest doesn't attempt to switch to vmmouse."""