Hello everyone, I'm new to both SocketCAN and mailing lists so please let me know if I'm making any faux pas or haven't correctly RTFMed! I heard this was the correct place to ask questions and I have a few that I haven't been able to find answers to. All my testing so far has been done on Ubuntu 20.04 with 5.15.0-43-generic and PCAN-USB( Pro) dongles and PCAN-PCI Express cards. Question 1: I've noticed that frames can get silently lost if my application doesn't read from the socket frequently enough. This also happens if I'm simultaneously dumping frames with candump (the "lost" frames do show up in candump's output). Increasing the socket receive buffer size with SO_RCVBUF allows more frames to be stored before new ones start getting lost. Is there a recommended way to detect this happening so that my program can fail noisily? Question 2: I'd like to be able to send frames without other receivers on the bus to acknowledge them. The one-shot option seems to allow me to do this with my USB dongles. What's the difference between the one-shot and presume-ack options? Question 3: I'd like to have as little latency as possible and I'm assuming using PCIe cards would be beneficial over USB. Unfortunately my PCAN-PCI Express card doesn't seem to support either one-shot or presume-ack; is that a hardware limitation or a driver limitation? If it's a hardware limitation, would anyone be able to recommend a low-latency, full-featured option for CAN on traditional x86/64 desktops? Thank you in advance! David
