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====== Michael Decker: Driver Development ======
==== Week C ====
----

=== 13 August ===

This morning I installed an **iSCSI** server on my laptop.  It turned out much simpler than anticipated.  I am running Ubuntu 8.04 (Hardy Heron), and it turns out the iSCSI target kernel module is present by default?  So, a point & click install via Synaptic Package Manager, and modification of ''/etc/ietd.conf'' was all that was needed.

Once working, I tested the **3c59x** driver I've been hacking on recently.  Of course there were network errors present, which I didn't see when using AoE.  A ''scandisk'' run over DOS froze up the system.

I spent a while going through the code and checking suspect areas.  I eventually discovered that the Linux code was freeing the tx buffers, which is a no-no in gPXE.  This code was fixed to issue ''netdev_tx_complete()'' notifications.  

Subsequent testing continued showing errors.  This baffled me for some time until I decided to reboot the laptop.  The next test showed no errors!  Interesting.  Further testing suddenly showed errors again.  I then discovered simply restarting Wireshark would prevent the TCP errors from appearing.  Further experimentation resulted in Wireshark crashing unexpectedly!?  So, while the universe seems broken, my driver is not :)

  * [[http://git.etherboot.org/?p=people/mdeck/gpxe.git;a=commit;h=5002142c055dbe3ab9cf9771dfb2cf83740cc988|[Drivers-3c59x] Fixed tx completion & more. Runs well]]

To be more clear: If the PC is restarted or turned off & on during a single Wireshark capture, subsequent TCP packets will be flagged as retransmissions.  However, if the Wireshark capture is restarted, no retransmissions will be flagged.  I suppose this has something to do with Wireshark's retransmission-identification heuristic, iSCSI's protocol format, and gPXE's TCP implementation.

I submit this driver for testing by anyone else before I trim out the old Linux driver code.

=== 15 August ===

Early start this morning:

  * [[http://git.etherboot.org/?p=people/mdeck/gpxe.git;a=commit;h=84a4676a41cc68607c56e3ad9731561b0d72b6b0|[Drivers-skge] Removed tx freeing, added tx completion notification]]

I tested the **skge** driver with iSCSI and found it freezing at a surface scan through ''scandisk'' in DOS.  I found in this driver I left in the tx iob freeing, and neglected tx completion notification - just as I did in 3c59x.  I also updated some comments.  Testing now reveals excellent operation via iSCSI.

  * [[http://git.etherboot.org/?p=people/mdeck/gpxe.git;a=commit;h=510bb9f5266d7d3faf68f2ea9b85bfa6d075f459|[Drivers-3c59x] Minor memory allocation corrections]]
  * [[http://git.etherboot.org/?p=people/mdeck/gpxe.git;a=commit;h=d2bb96476733a911f512ae2f6f34cc2bceeba781|[Drivers-3c59x] Code cleanup]]

Pushed a few minor **3c59x** memory allocation fixes.  Removed all the old Linux code from 3c59x.  I feel the driver is ready for prime-time, so I pruned out that code.  It's nice and shiny now. ;)

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