我通过jtag启动时，显示No supported FPGA device found，请问这是什么原因呢
wyn@ubuntu:~/Desktop/test/xilinx-kc705-axi-full-2019.2$ petalinux-boot --jtag --prebuilt 3
INFO: sourcing build tools
INFO: Launching XSDB for file download and boot.
INFO: This may take a few minutes, depending on the size of your image.
rlwrap: warning: your $TERM is 'xterm-256color' but rlwrap couldn't find it in the terminfo database. Expect some problems.: Inappropriate ioctl for device
INFO: Configuring the FPGA...
INFO: Downloading bitstream: /home/wyn/Desktop/test/xilinx-kc705-axi-full-2019.2/pre-built/linux/implementation/download.bit to the target.
No supported FPGA device found
invoked from within
"::tcf::eval -progress ::xsdb::print_progress {::tcf::cache_enter tcfchan#0 {tcf_cache_eval {process_tcf_actions_cache_client ::tcfclient#0::arg}}}"
(procedure "::tcf::cache_eval_with_progress" line 2)
invoked from within
"::tcf::cache_eval_with_progress [dict get $arg chan] [list process_tcf_actions_cache_client $argvar] $progress"
(procedure "process_tcf_actions" line 1)
invoked from within
"process_tcf_actions $arg ::xsdb::print_progress"
(procedure "fpga" line 430)
invoked from within
"fpga "/home/wyn/Desktop/test/xilinx-kc705-axi-full-2019.2/pre-built/linux/implementation/download.bit""
(file "/tmp/tmp.zFN92DBeMS" line 5)
INFO: The XSDB log is as follows
attempting to launch hw_server
****** Xilinx hw_server v2019.2
**** Build date : Oct 23 2019 at 23:11:29
** Copyright 1986-2019 Xilinx, Inc. All Rights Reserved.
INFO: hw_server application started
INFO: Use Ctrl-C to exit hw_server application
INFO: To connect to this hw_server instance use url: TCP:127.0.0.1:3121
