MIDI support on Linux is fairly mature and usually hassle-free.  Most, if not all current distributions will support MIDI out of the box. 

===== Firmware =====
Some USB MIDI interfaces require firmware to be uploaded to them before they function.  This must be done EVERY time the interface is plugged in.  Fortunately there are programs available to automatically handle this.

==== Debian/Ubuntu ====
=== MidiSport Series ===
  sudo apt-get install midisport-firmware

==== Redhat/Fedora ====
==== Suse ====

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===== Known Good =====
These interfaces are known to be fully supported:

* M-Audio MidiSport 1x1 (needs firmware loader)

* M-Audio MidiSport 2x2 (needs firmware loader)




===== Known Bad =====

* MOTU Fastlane\\
This one will not work with kernels 2.6.18 and newer.  This rules out most current distributions.  Avoid it if you can.  Ubuntu 6.10 (edgy eft) is known to be able to use this interface.


===== Untested =====
* M-Audio MidiSport 4x4

* M-audio MidiSport 8x8

* Emu XMIDI

* Eridol/Roland

* Generic USB-MIDI devices (supporting MIDISTREAM subclass)

* Turtle Beach

* Yamaha

===== Does it Work? =====
To check that things work, plug in your cables and attach a MIDI keyboard to the IN port.  Then type:
  awmidi -l
This will list available MIDI interfaces.  You should see something like this:
  Dir Device    Name
  IO  hw:0,0    ES1371
Now type:
  awmidi -d -p hw:0,0
Replace "hw:0,0" with whatever you get as a Device.  Now press some keys.  You should see a stream of hexadecimal numbers.  This is good.