Compiling issues: regarding "-march=native"

[tohidhajimorad]

Detail
cpu: Intel core i7 11375H
system: Ubuntu 20.04 LTS
gcc version: gcc-9
aarch64-linux-gnu-gcc version: gcc-9-aarch64-linux-gnu

Issue
When compiling using
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE=../toolchains/jetson.toolchain.cmake -DNCNN_VULKAN=ON -DNCNN_BUILD_EXAMPLES=ON ..

it returns

-- NCNN_VERSION_STRING = 1.0.20230111
-- The C compiler identification is GNU 9.4.0
-- The CXX compiler identification is GNU 9.4.0
-- Check for working C compiler: /usr/bin/aarch64-linux-gnu-gcc
-- Check for working C compiler: /usr/bin/aarch64-linux-gnu-gcc -- broken
CMake Error at /usr/share/cmake-3.16/Modules/CMakeTestCCompiler.cmake:60 (message):
The C compiler

"/usr/bin/aarch64-linux-gnu-gcc"
is not able to compile a simple test program.

It fails with the following output:

Change Dir: /home/ealin/ncnn/build/CMakeFiles/CMakeTmp

Run Build Command(s):/usr/bin/make cmTC_753ed/fast && /usr/bin/make -f CMakeFiles/cmTC_753ed.dir/build.make CMakeFiles/cmTC_753ed.dir/build
make[1]: Entering directory '/home/ealin/ncnn/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_753ed.dir/testCCompiler.c.o
/usr/bin/aarch64-linux-gnu-gcc -march=native -o CMakeFiles/cmTC_753ed.dir/testCCompiler.c.o -c /home/ealin/ncnn/build/CMakeFiles/CMakeTmp/testCCompiler.c
cc1: error: unknown value ‘native’ for ‘-march’
cc1: note: valid arguments are: armv8-a armv8.1-a armv8.2-a armv8.3-a armv8.4-a armv8.5-a
make[1]: *** [CMakeFiles/cmTC_753ed.dir/build.make:66: CMakeFiles/cmTC_753ed.dir/testCCompiler.c.o] Error 1
make[1]: Leaving directory '/home/ealin/ncnn/build/CMakeFiles/CMakeTmp'
make: *** [Makefile:121: cmTC_753ed/fast] Error 2
CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
CMakeLists.txt:48 (project)

When I check with /usr/bin/aarch64-linux-gnu-g++ -Q --help=target, the march part says -march= armv8-a.

The jetson.toolchain.cmake file has the line

-march=armv8-a could work on Jetson, but will compile without some extra cpu features

Questions
Why 'native' is not recognized for -march and how to fix it?
Which features are neglected if compiling with "-march=armv8-a"?

[nihui]

jetson.toolchain.cmake is used for compiling natively on jetson board
If you mean to cross-compiling for arm board, use aarch64-linux-gnu.toolchain.cmake