I've built the experimental branches of lora_gateway and packet_forwarder from under the Lora-net GitHub organisation. Configuring libloragw for native SPI, with lora_pkt_fwd using the basic global config, and then the local config populated with settings validated to work with poly_pkt_fwd built from the TTN packet_forwarder repository.
However, when I try to start lora_pkt_fwd it crashes out with:
INFO: fake GPS is enabled
Note: SPI port opened and configured ok
Note: SPI write success
Note: SPI read success
ERROR: VERSION=0, CONCENTRATOR SEEMS DISCONNECTED
ERROR: FAIL TO CONNECT BOARD
ERROR: [main] failed to start the concentrator
Which is strange, as poly_pkt_fwd plus libroragw from the TTN repo works, and as far as I can tell, this and the libloragw from Lora-net/experimental both use the same host SPI device and speed. Although I note that the latter library does not have a PLATFORM option in the config, whereas the TTN version does and this is set to imst_rpi.
Also, any update on TTN support for ACK?