> A huge amount of manpower in getting all these pieces into shape. Not wrong, but a lot easier in recent years as compared to the past, as historically there

> A huge amount of manpower in getting all these pieces into shape. Not wrong, but a lot easier in recent years as compared to the past, as historically there were a lot of closed-source systems. Nowadays, with the popularity and ubiquity of open source, one can 'brute force' writing for Linux, GCC, and LLVM, and you've probably a sizeable portion of use cases covered. (You may have difficultly in getting things into mainline if you've got a niche ISA, so there's continuing overhead of maintaining patches.)