I always figured that a major source of complexity in drivers was papering over imperfections in the underlying hardware.
I imagine things like video and chipset drivers are full of "if we're on stepping A0 or A1 hardware, we have to do this magic wiggle dance to get feature XYZ to actually work" hacks, most of which are only documented within the manufacturer's own propriatery-driver team.
There's probably also a lot of compromise for external confounding variables-- "Our part works to spec 98% of the time, but if you install it in specific systems, they're at a specific corner of the compatibility envelope, and you have to do ABC to get it actually stable."
I'd suspect as a result, something like "Driver for VirtualBox SVGA" is going to be a lot simpler than a comparable level of functionality targeting real hardware. OTOH, we do have stuff like 86box which seems to be trying to be a closer simulation of real hardware.
I imagine things like video and chipset drivers are full of "if we're on stepping A0 or A1 hardware, we have to do this magic wiggle dance to get feature XYZ to actually work" hacks, most of which are only documented within the manufacturer's own propriatery-driver team.
There's probably also a lot of compromise for external confounding variables-- "Our part works to spec 98% of the time, but if you install it in specific systems, they're at a specific corner of the compatibility envelope, and you have to do ABC to get it actually stable."
I'd suspect as a result, something like "Driver for VirtualBox SVGA" is going to be a lot simpler than a comparable level of functionality targeting real hardware. OTOH, we do have stuff like 86box which seems to be trying to be a closer simulation of real hardware.