found a problem with bridges on reboot, with a fix

howto/ganeti.md

@@ -882,6 +882,28 @@ often, by scheduling a [harep](http://docs.ganeti.org/ganeti/2.15/man/harep.html
 Debian by default. See also the [autorepair](http://docs.ganeti.org/ganeti/2.15/html/admin.html#autorepair) section of the admin
 manual.
 
+### Bridge configuration failures
+
+If you get the following error while trying to bring up the bridge:
+
+    root@chi-node-02:~# ifup br0
+    add bridge failed: Package not installed
+    run-parts: /etc/network/if-pre-up.d/bridge exited with return code 1
+    ifup: failed to bring up br0
+
+... it might be the bridge cannot find a way to load the kernel
+module, because kernel module loading has been disabled. Reboot with
+the `/etc/no_modules_disabled` file present:
+
+    touch /etc/no_modules_disabled
+    reboot
+
+It might be that the machine took too long to boot because it's not in
+mandos and the operator took too long to enter the LUKS
+passphrase. Re-enable the machine with this command on mandos:
+
+    mandos-ctl --enable chi-node-02.torproject
+
 ### Other troubleshooting
 
 Riseup has [documentation on various failure scenarios](https://we.riseup.net/riseup+tech/ganeti#failure-scenarios) including