====== Piotr Jaroszyński: Usermode debugging under Linux ======

====== How to use Linux usermode ======

===== Building =====
  $ make bin-x86_64-linux/gpxe.linux

===== Runing =====
  $ ./bin-x86_64-linux/gpxe.linux --net tap,if=tap3,mac=52:54:00:12:34:56 --net tap,if=tap4,mac=52:54:00:12:34:57 # etc

===== Setting up tap =====
==== Prerequisites ====
  * Linux config:
<code>
  CONFIG_BRIDGE=y
  CONFIG_TUN=y
</code>
  * ''tunctl'' tool
  * ''brctl'' tool

==== Setting up the bridge ====

Assuming ''eth0'' is the primary network interface used for networking.
  * Disable current networking
  * Add a bridge
<code>
  # brctl addbr br0
</code>
  * Add ''eth0'' to the bridge
<code>
  # brctl addif br0 eth0
</code>
  * Start networking on ''br0''
<code>
  # dhclient br0
</code>

At this point networking should be working as normal.

==== Setting up the tap interfaces ====
  * Create a tap device
<code>
  # tunctl -u $USER -t tap1 # -u so that we don't need root to access the device
</code>
  * Enable it
<code>
  # ifconfig tap1 up
</code>
  * Add it to the bridge
<code>
  # brctl addif br0 tap1
</code>

At this point the tap1 interface should be usable in gPXE usermode. Multiple interfaces can be added like that.