Hi Dmitry, > Subject: Re: [PATCH v6 00/10] Support virtio-gpu DRM native context > > On 2/6/25 01:13, Dmitry Osipenko wrote: > > On 2/5/25 23:08, Dmitry Osipenko wrote: > >>> Thanks for showing me the video. I will take a look and check what would > go wrong here. I kinda understand corruption may happen > >>> in some scenario but I don't know what could cause the upside down > image. Do you have any idea?? Maybe the frame was temporarily replaced > with > >>> a mishandled texture that QEMU creates from the surface temporarily but > I am not sure.. > >> No clue. Could be anything. Could be a GTK/Wayland bug, could be an > >> obscure QEMU bug. GTK expert wanted here. > > > > Alright, it's bugged with "blob=on", but works with "blob=off". While I > > don't see QEMU using blobs. Might be QEMU's bug then. > > > > Looked further at it. So QEMU was using blobs with "blob=on" and I was > looking at a wrong place. Then I found that setting y0_top=true for > dmabuf makes display to show upside down, but there is no rendering bug > with it. Something redraws display with y0_top=true, while it should be > y0_top=false. I couldn't figure out how it's related to the offending > change. It is possible that the additional draw call (offending change) is exposing a bug elsewhere. This is because having both blob=on and virgl=on was not a valid combo until recently. IIUC, virgl directly calls gd_gl_area_scanout_texture() with y0_top=true (sometimes) but I guess gd_gl_area_scanout_texture() might be getting called again with yo_top=false via gd_gl_area_scanout_dmabuf() in the same repaint cycle?
> > I also noticed that QEMU checks Wayland presence in > early_gtk_display_init() and doesn't use EGL callbacks that are used for > X11 display, but the y0_top logic looks the same. Interestingly, Windows > should be using same display code paths as Wayland, but I don't have > ability to test Windows. > > If nobody will be able to fix the bug soon, at least reverting the > Wayland part will be good to do. Hope we can find a proper fix soon but looks like Dongwon already sent the patch to revert the changes in gtk-gl-area.c. Thanks, Vivek > > -- > Best regards, > Dmitry
