2021-10-20 03:34:26 +00:00
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# OpenWrt inside a user mode linux
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> Why would we even want this many ask?
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There are potentially a lot of reasons, one obvious one to me, it allows folks
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to 'kick the tires' without actually flashing up any hardware. It's also a
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great environment for porting over packages, you can get a package fully
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functional in the uclibc root environment inside a uml without actually
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disturbing your 'real router', and then rebuild for a specific target once it's
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fully tested.
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This is a first stab at a build that 'just works' and there will be more
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cleanup to come. The simple directions are:-
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* Configure for uml target
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* Configure with an ext4 or squashfs root file system
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* Build it all
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In your bin directory you will find a Kernel and an root file system when it's
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finished. Just run it like this:-
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```shell
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./openwrt-uml-vmlinux ubd0=openwrt-uml-squashfs.img
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```
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The uml will start and eventually the serial console of the uml will be at your
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console prompt. If you would like it in xterms, substitute `con=xterm` and
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`con0=xterm`. **No networking is configured** but it's a starting point. The
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resulting file system has just enough free space to start kicking the tires and
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playing in the world of 'embedded routers' along with all the resource
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2022-08-06 17:44:02 +00:00
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restrictions that come with that world.
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2021-10-20 03:34:26 +00:00
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To configure networking and more refer to the *user mode linux* documentation
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online. A quick start goes along this line. Install the `uml-utilities`
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packages so you have the `uml_switch` in and running, then add a command param
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to your uml start like this:
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```shell
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eth0=daemon,00:01:01:01:01:01,unix,/<your uml switch control socket here>
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```
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With that in, and uml networking actually functional (can be a challenge at
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times), you should be able to `ifconfig` the interface and talk to the host
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side or if you bridged the uml switch to your host network, you should be able
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to run `udhcp` and be away with networking off to the world. Again, if you are
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unfamiliar with uml and uml networking, please read the docs and how-to stuff
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available on the net. It does take some fiddling to get it started and working
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right the first time, but after that, it opens up a whole new world of virtual
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machines.
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http://user-mode-linux.sourceforge.net/
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