[fedora-arm] Re: what do i have to do to enable spi on fedora 27 on a raspberry pi

You might try Fedberry. I uncommented "dtparam=spi=on" in /boot/config.txt and now see the /dev/spidev0.0 and /dev/spidev0.1 devices. The GPIO devices (gpiochip0, gpiochip1, and gpiochip2) are present by default, without any special configuration.

With F27, uncertain about what device tree overlay capabilities actually exist, I experimented by manually adding the SPI text to the initial binary device tree file (dtc from binary or tree to source, edit, dtc back to binary) but this did not work. I wonder whether the F27 SPI DT overlay data may be incomplete (Raspbian has more detail), or if your suspicion about kernel configuration is the fundamental problem.

I2C is what I need currently, and F27 has been very good for that.