JTAG-disable jumper disables the whole chain
The JTAG disable jumper is a safety feature to prevent accidental JTAG machine switching. It needs to be noted in the user manual that with the jumper installed, the whole chain is disabled.
With TRST disconnected from the FMC connector, nanoFIP JTAG is still detected by JTAG adapter connected to the carrier board (tested on Xilinx SP601). This way TRST is accessible from the JTAG header on the mezzanine, but does not break the whole JTAG chain.