I had the distinct misfortune to port an HPC & ethernet driver stack to AIX in the early 2000s. It was kinda BSD (mbufs), and kinda not (everything else), and just generally weird.
Having a test machine that took ~20 minutest to panic and reboot made the process extra fun.
It was one of the more annoying systems to develop drivers for that I've ever used. And I've done drivers for various BSDs, Linux, MacOS, ESX, Solaris, and even Tru64.
I would have used VIOS for that situation and passed the PCI device through to the LPAR for most the work. It would be about 5 minutes if you had reasonable disks and you could just barrel fish several cards and LPARs for intense debugging sessions.
Yeah...the first rule of AIX Club is AIX isn't (wasn't) old-school Unix. You actually had to learn AIX.
Back when I was in that game, we had an AIX guru spend a week or two teaching our kernel devs how things actually worked and at the end everyone was "even if I don't agree with how you did things, I understand how to make things work". We saw lot of folks try and shoehorn their view of Unix into AIX and it never ended well.
My first five minutes on an AIX machine involved trying to find a logfile to read...this is how I discovered 'errpt'; and the (new to me) IBM habit of giving certain cli output in all-caps. "Why is this machine shouting at me?"
I did end up liking it a lot, and I wish I had more of them. Once you set aside your expectations about what a unix should act like, it was kinda fun.
Having a test machine that took ~20 minutest to panic and reboot made the process extra fun.
It was one of the more annoying systems to develop drivers for that I've ever used. And I've done drivers for various BSDs, Linux, MacOS, ESX, Solaris, and even Tru64.