document how to setup vbmc

Author: evgeni

docs/bmc.md

@@ -18,6 +18,32 @@ This is a set of simple simulation tools aimed at supporting the development and
 ### VirtualBMC
 
 * [Github](https://github.com/openstack/virtualbmc)
+* Fedora: `python3-virtualbmc`
 
 A virtual BMC for controlling virtual machines using IPMI commands.
 
+The virtual BMC consists of two parts:
+* `vbmcd` the daemon that exposes virtual BMCs
+* `vbmc` the client that can be used to configure the daemon
+
+The `vbmcd` daemon needs to run as a user that has access to the libvirt instance.
+If you're using `qemu:///session` for libvirt, you can run `vbmcd --foreground` as your user.
+If you're using `qemu:///system` for libvirt, you can use the `vbmcd.service` provided by the Fedora package.
+
+Once `vmbcd` is running, you can add virtual BMCs using the `vbmc` client:
+```
+$ vbmc add --libvirt-uri qemu:///session libvirt_domain_name
+```
+or
+```
+$ vbmc add --libvirt-uri qemu:///system libvirt_domain_name
+```
+
+The username and password of the BMC can be changed using `--username` and `--password`.
+The port can't be changed with `--port` as Foreman doesn't allow configuring any other port than `623/udp`
+
+You might need to allow `623/udp` in your firewall: `sudo firewall-cmd --zone=libvirt --add-port=623/udp`.
+
+If you're running `vbmcd` as an unprivileged user, you'll need to allow it to bind to 623: `sudo sysctl net.ipv4.ip_unprivileged_port_start=0`.
+
+Once everything is configured, you can start the virtual BMC with `vbmc start libvirt_domain_name` and Foreman should be able to control the machine using IPMI.