# Linux Kernel Module Cheat

##### 2.8.2.3. Userland setup getting started full system

First ensure that QEMU Buildroot setup is working.

After doing that setup, you can already execute your userland programs from inside QEMU: the only missing step is how to rebuild executables and run them.

And the answer is exactly analogous to what is shown at: Section 2.2.2.2, “Your first kernel module hack”

For example, if we modify userland/c/hello.c to print out something different, we can just rebuild it with:

    ./build-userland

Source: build-userland. `./build` calls that script automatically for us when doing the initial full build.

Now, run the program either without rebooting use the 9P mount:

    /mnt/9p/out_rootfs_overlay/c/hello.out

or shutdown QEMU, add the executable to the root filesystem:

    ./build-buildroot

reboot and use the root filesystem as usual:

    ./hello.out