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explain bordervm

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Daniel Barlow 2023-02-17 20:03:57 +00:00
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60
doc/developer.rst
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@ -110,8 +110,64 @@ do something like this:
and then issue appropriate U-boot commands to download and flash the
image.
For quicker development cycle, you can build a TFTP-bootable image
instead of flashing. [ .... add this bit ....]
For a faster edit-compile-test cycle, you can build a TFTP-bootable
image instead of flashing. In your device configuration add
.. code-block:: nix
imports = [
./modules/phram.nix
];
boot.tftp = {
serverip = "192.168.200.148";
ipaddr = "192.168.200.251";
};
and then build ``outputs.tftproot``. This creates a file in
``result/`` called ``boot.scr`` containing commands that you can copy
and paste into U-Boot which will transfer the kernel and filesystem
over TFTP and boot the kernel from RAM.
Networking
==========
You probably don't want to be testing a device that might serve DHCP,
DNS and routing protocols on the same LAN as you (or your colleagues,
employees, or family) are using for anything else, because it will
interfere. You also might want to test the device against an
"upstream" connection without having to unplug your regular home
router from the internet so you can borrow the cable/fibre/DSL.
``bordervm`` is included for this purpose. You will need
* a Linux machine with a spare PCI ethernet card which you can dedicate to Liminix
* an L2TP service such as https://www.aa.net.uk/broadband/l2tp-service/
You need to configure the Ethernet card for VFIO passthru, then
you can execute ``run-border-vm`` in a ``buildEnv`` shell,
which starts up QEMU using the NixOS configuration in
``bordervm-configuration.nix``
In this VM
* your Liminix checkout is mounted under ``/home/liminix/liminix``
* TFTP is listening on the ethernet device and serving
``/home/liminix/liminix``. The server IP address is 10.0.0.1
* a PPPOE-L2TP relay is running on the same ethernet card, which
spawns L2TPv2 Access Concentrator sessions to your specified
L2TP LNS when the connected Liminix device makes PPPoE requests.
Note that authentication is expected at the PPP layer not the L2TP
layer, so the same PAP/CHAP credentials provided by your L2TP
service can be configured into your test device - bordervm
doesn't need to know about them.
To configure bordervm, you need a file called ``bordervm.conf.nix``
which you can create by copying and appropriately editing ``bordervm.conf-example.nix``
Running tests