If JTAG access fails, make sure that you have an
udev rule in
place that tags the JTAG device with uaccess. All devices with this tag are
configured so that all local users can access them. You can either install
a driver from Xilinx (which actually is just some udev rules, since the real
driver --- ftdi_sio --- is part of the linux kernel), or you can manually
place the rule. It is important that your rule is lexically before 73-seat- late.rules, otherwise setting the TAG+="uaccess" does not have any effect.
You can quite easily formulate the rule yourself: use lsusb to find the
vendor id and product id of the JTAG probe.
$ lsusb
# ...
Bus 004 Device 009: ID 0403:6010 Future Technology Devices International, Ltd FT2232C/D/H Dual UART/FIFO IC
# ...
In this example, the FTDI device has the vendor id 0403 and the product id
6010. Now, the udev rule only has to be formulated to tag any device matching
this combination of vendor and product id with the uaccess flag:
ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", TAG+="uaccess"
Save that rule to a file that is executed before 73-seat-late.rules, e.g.
61-xilinx-jtag-probe.rules in /etc/udev/rules.d. This rule tags the device,
and once 73-seat-late.rules is executed all tagged devices are configured so
that normal, local users (thus the seat in 73-seat-late.rules) can access
the device.