-Old-Kits: Building Linux Userspace Applications

This application note explains how to build a Linux userspace application from the Linux-hosted cross development environment and then to deploy the built executable on the target.

On the development host, install the prebuilt Yocto toolchain from here.

Activate the toolchain:

$ source /opt/st/stm32mp1-som/2.4-snapshot/environment-setup-cortexa7hf-neon-vfpv4-openstlinux_weston-linux-gnueabi
$ unset CCACHE_PATH

Now the CC, LD, CFLAGS and the others standard build environment variables are set for cross-compilation for the STM32MP1 platform, eg:
```
$ $CC hello.c -o hello
...
```
To deploy the build executable to the target, copy it to a USB Flash and plug in the USB Flash into any of USB connectors on the board:
```
$ mount /dev/sda1 /media
$ cp /media/hello /tmp
$ /tmp/hello
Hello from STM32MP1-SOM!
$
```
Alternatively, you could deploy your application from the host to the target using scp:
```
$ scp hello root@172.17.13.11:/tmp
```
Another way of deploying the binary to the target is the exporting the build directory as an NFS share. Having NFS configured on your host, run on the target:

$ mount -o nolock 172.17.0.19:/work/stmp1 /mnt
$ ls -l /mnt
...
-rwxrwxr-x   1 1002  1002     14612 Apr 16 20:37 hello
-rw-rw-r--   1 1002  1002       219 Apr 16 20:36 hello.c
$ cp /mnt/hello /tmp
$