Using FireWire on a Raspberry Pi
jeffgeerling.comI always feel Apple made a real blunder with the FireWire licensing situation. FW was really interesting: It was a real memory mapped computer bus like PCI that also supported peer-to-peer operation. It was vastly superior to USB and had a lot of potential. That is, if you knew that Firewire was Apple's trademark, I.LINK was Sony's, Lynx was Texas Instruments, and generic IEEE-1394/1394 labels everyone non-technical was supposed to somehow understand. Great tech hamstrung by greed.
Then again, remote DMA to your memory via a port on the computer, while a great tool for debugging internal stuff, is also quite the wide door to getting hacked if someone every manages to plug in a malicious device in the same port.
It's funny how we've come back around to this, with the M3 Mac Studios allowing you to enable RDMA over Thunderbolt. You have to toggle the setting via a firmware change, but it's there for performance!
FireWire was pretty wild in its day. It just got hampered by the per-port licensing fee, and once USB 2.0 rolled out, its days were numbered for anyone not needing the latency/power features.
IOMMU solved this issue with virtual memory mapping for MIMO hardware.