The gist of it is that breakage is OK if the userspace isn't open-source and that new uAPIs come around every few years due to the rapid pace development of GPUs.
I worked on Chrome OS graphics for years on and one of my earliest projects was to bring DRM/KMS (then a newish interface) to the Cirrus display card (an ancient card that QEMU happens to emulate).
The gist of it is that breakage is OK if the userspace isn't open-source and that new uAPIs come around every few years due to the rapid pace development of GPUs.
I worked on Chrome OS graphics for years on and one of my earliest projects was to bring DRM/KMS (then a newish interface) to the Cirrus display card (an ancient card that QEMU happens to emulate).