Hi @dongyang12!
1 >> Yes, Onxx only runs on the CPU.

2 >> You have to follow the next steps to generate the toolchain:
Install the repo utility:
$: mkdir ~/bin
$: curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
$: chmod a+x ~/bin/repo
$: PATH=${PATH}:~/bin
Download the Yocto Project BSP
$: mkdir <release>
$: cd <release>
$: repo init -u https://github.com/nxp-imx/imx-manifest -b <branch name> [ -m <release manifest>]
$: repo sync
Setup the build folder for a BSP release:
$: [MACHINE=<machine>] [DISTRO=fsl-imx-<backend>] source ./imx-setup-release.sh -b bld-<backend>
<machine> defaults to `imx6qsabresd`
<backend> Graphics backend type xwayland
Wayland with X11 support - default distro
wayland Wayland
fb Framebuffer (not supported for mx8)
Build SDK:
bitbake -c populate_sdk imx-image-full
Best Regards!
Chavira