In October 2020, after Raspberry Pi introduced the Compute Module 4, I started out on a journey to get an external graphics card working on the Pi.
At the time, it'd been over a decade since the last time I'd built a PC, and I had a lot to learn about PCI Express, the state of graphics card drivers in Linux, and PCI Express support on various ARM SoCs.
Since the Raspberry Pi Compute Module 4 was introduced last year, I've been testing a variety of PCI Express NICs with it. One of the main types of NIC I'm interested in is cheap 2.5 Gigabit Ethernet adapters.
2.5 Gigabits is about the highest reasonable bandwidth you can get through the PCI Express Gen 2.0 x1 lane on the Raspberry Pi, and it's also a lot more accessible than 10 Gigabit networking, especially for home users who might already have Cat5e runs that they are loathe to swap out for Cat6 or better cabling.
In my testing, besides discovering that not all 10 Gbps SFP+ transceivers are created equal, I found out that when it comes to performance, the Linux driver you're using matters—a lot.
It always seems to happen after a major OS upgrade—no matter what the operating system... You go to print, and all the sudden you get a warning saying your printer drivers are not up-to-date or are not installed correctly.
In my case, I tried printing to my trusty and reliable Brother HL-2140 (laser printer), and I got a warning that Apple needed to update its drivers via Software Update. I let it try, but that failed. Any time I sent a new print job, the printer dialog simply told me there was an error, and the drivers were out of date.
I then deleted and added the printer in the Print & Scan system preference pane, which sometimes helps, but in this case did not. My printer is listed as being compatible with OS X 10.6 / Lion (check your own printer here), so that shouldn't be a problem. But, as is the case almost always, giving things a big konk in the head works.