Needs a more recent openocd than is currently available in openwrt/packages:
opkg update
wget https://kevinmehall.net/tmp/openocd_d3c2679bcb8e8ba25e7b6e443b39f57474afc099-2_ramips_24kec.ipk -O /tmp/openocd.ipk
opkg install /tmp/openocd.ipk
rm /tmp/openocd.ipk
In another terminal:
scp openocd.cfg [email protected]:
ssh [email protected] openocd -f openocd.cfg
In a tessel/t2-firmware checkout:
arm-none-eabi-gdb build/firmware.elf -ex 'target remote 192.168.128.116:3333'