On Tue, Mar 25, 2025 at 06:12:51PM +0100, Thomas Zimmermann wrote: > Remove internal adjustments to framebuffer format from cirrus-qemu > driver. The driver did this to support higher resolutions by reducing > the per-pixel memory consumption. > > DRM has a policy of exporting formats as they are implemented in > hardware. So avoid internal adjustments if possible. Well. While this policy makes sense for modern hardware this is IMHO not the case for the cirrus. First, because there is almost no userspace which can handle the ancient 24 bpp format (DRM_FORMAT_RGB888). Second, because there is no way to communicate the hardware constrains of the cirrus. userspace can query the formats, and userspace can query the resolutions, but there is no way to tell userspace that not all combinations are valid and that you have to go for the DRM_FORMAT_RGB565 format if you want higher resolutions. Essentially the format conversations allows the driver to hide the oddities of the prehistoric hardware from userspace, so things are more smooth when running wayland on the cirrus. take care, Gerd PS: https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/ still applies of course.
