Reading and writing to AXI Stream

[Prandr]

First of all, thank you for your effort! You basically do what should be Xilinx's/AMD's job.
I'd like to ask, why do you use pread and pwrite instead of simple read and write in the AXI-Stream example?
It doesn't seem to make sense since AXI Stream doesn't require an address.

[mwrnd]

I encountered an issue with multiple writes, remembered that write increments file position within a file descriptor, then settled on using pwrite. I did not explore this further.

Indeed, addresses make no sense with AXI Stream. However, because dma_ip_drivers presents it as a seekable file, I believe it is consistent with how Linux works to be explicit about a file position. I updated my notes.

[Prandr]

Looking at char_sgdma_read_write I don't see where the offset would be incremented, unlike char_ctrl_write. You could do a write and then call
lseek(fd, 0, SEEK_CUR)
to see if the address/offset/position in the file descriptor has been changed.