[9fans] Nemo's Opus

[Brantley Coile <brantleycoile@me.com>]

I’ve been reading Nemo’s “Notes on the Plan 9 3rd edition Kernel Source” after a number of years. Three things struck me on this reading of what is a great and much appreciated work. First, is what a good job Francisco did with this work. Even though he never finished it, having been overtaking, I think, by the 4th edition, it is a very good introduction to an operating system suitable for instruction in a undergraduate or graduate class in operating systems. I, fortunately, don’t have to teach, but if I did, I would certainly use the work.

Second, I’m struck by how much larger the system had grown by the time Nemo wrote the commentary. I had the good fortune to read John Lion’s commentary on Plan 9 during my brief tenure at Bell Labs in 1990. If I remember right, the kernel I was using was bout 25,000 lines. The first version I used outside the Labs was the 2nd edition it weighs in at a hefty 39,000 lines. The current system I’m running, the 32 bit one, not the 64 bit one, is 140,000 lines. I’m not sure the size of the 3rd edition, but the growth is interesting.

The third thing that struct me is the changes in the Intel architecture since the original PC based port. The first Plan 9 for PC ran on AT&T 386 machines in the 1990’s, if I remember right. Those were the days of ISA and EISA and before PCI made it’s plug-and-play appearance on the scene. It seems that while the PC stuff has kept up with most of the many changes in the Intel hardware platform over the years, there is still some cruft from the old days. 

All very interesting to think about. I highly recommend Nemo’s book. Here’s a link to it.

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.75.5409&rep=rep1&type=pdf

  Brantley Coile
  bwc@coraid.com
  http://coraid.com