From my experience working on GPU drivers, the ISA is one of the least important parts of porting. 99% of the time, it's just changing a compiler flag. Thankful

From my experience working on GPU drivers, the ISA is one of the least important parts of porting. 99% of the time, it's just changing a compiler flag. Thankfully, the era of "Ancient Quirky Proprietary Toolchain" is a thing of the past, even on small embedded platforms. Sure, you might have have a little "optimised" ASM for some specific conversions, but that's always just performance, and a driver even touching bulk data on the CPU means you're already in the slow path. Stuff like how the busses are enumerated, cache coherency specifics, and interoperability with other devices (some mobile SoCs can be a grab bag of different GPU/Display block/Video encoder/Image processing/whatever else) is waayyyyy more important from what I've seen/. And while we all hate on stuff like PCI and ACPI, at least it's (kinda) standard and (somewhat) works.