gdb Don't know how to run target in cross-compiler environment - c++

Question

I want to debug gtest ut exec file. but it failed to use aarch64-poky-linux-gdb run.
my host is x86 environment, and my compile environment is arm64.
This GDB was configured as "--host=x86_64-pokysdk-linux --target=aarch64-poky-linux".
I used this cmd to run
$ aarch64-poky-linux-gdb --args ./unittests/ut_settings --gtest_filter=SettingsTestSuite.testParseStatus
$ file ut_settings
ut_settings: ELF 64-bit LSB shared object, ARM aarch64, version 1 (GNU/Linux), dynamically linked, interpreter /lib/ld-linux-aarch64.so.1, BuildID[sha1]=cb6d795bd316fb829ddd26caf317240532105469, for GNU/Linux 3.14.0, with debug_info, not stripped
but when i typed run, it cannot run
(gdb) r
Don't know how to run. Try "help target".
but is use ctest it can run, so i guess it can be use gdb debug, but i don't know how to. can some one help me how to run it
the entire log
$ aarch64-poky-linux-gdb --args ./unittests/ut_settings --gtest_filter=SettingsTestSuite.testParseStatus
GNU gdb (GDB) 9.1
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-pokysdk-linux --target=aarch64-poky-linux".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from ./unittests/ut_settings...
(gdb) r
Don't know how to run. Try "help target".
(gdb) help target
Connect to a target machine or process.
The first argument is the type or protocol of the target machine.
Remaining arguments are interpreted by the target protocol. For more
information on the arguments for a particular protocol, type
`help target ' followed by the protocol name.
List of target subcommands:
target core -- Use a core file as a target.
target exec -- Use an executable file as a target.
target extended-remote -- Use a remote computer via a serial line, using a gdb-specific protocol.
target record-btrace -- Collect control-flow trace and provide the execution history.
target record-core -- Log program while executing and replay execution from log.
target record-full -- Log program while executing and replay execution from log.
target remote -- Use a remote computer via a serial line, using a gdb-specific protocol.
target tfile -- Use a trace file as a target.
Type "help target" followed by target subcommand name for full documentation.
Type "apropos word" to search for commands related to "word".
Type "apropos -v word" for full documentation of commands related to "word".
Command name abbreviations are allowed if unambiguous.