openwrt-pf/target/linux/uml

OpenWrt inside a user mode linux

Why would we even want this many ask?

There are potentially a lot of reasons, one obvious one to me, it allows folks to 'kick the tires' without actually flashing up any hardware. It's also a great environment for porting over packages, you can get a package fully functional in the uclibc root environment inside a uml without actually disturbing your 'real router', and then rebuild for a specific target once it's fully tested.

This is a first stab at a build that 'just works' and there will be more cleanup to come. The simple directions are:-

• Configure for uml target
• Configure with an ext4 or squashfs root file system
• Build it all

In your bin directory you will find a Kernel and an root file system when it's finished. Just run it like this:-

./openwrt-uml-generic-vmlinux ubd0=openwrt-uml-generic-squashfs.img

The uml will start and eventually the serial console of the uml will be at your console prompt. If you would like it in xterms, substitute con=xterm and con0=xterm. No networking is configured but it's a starting point. The resulting file system has just enough free space to start kicking the tires and playing in the world of 'embedded routers' along with all the resource restrictions that come with that world.

To configure networking and more refer to the user mode linux documentation online: https://docs.kernel.org/virt/uml/user_mode_linux_howto_v2.html#setting-up-uml-networking

Actually functional uml networking can be a challenge at times. Again, if you are unfamiliar with uml and uml networking, please read the docs and how-to stuff available on the net. It does take some fiddling to get it started and working right the first time, but after that, it opens up a whole new world of virtual machines.