Re: [9fans] Writing drivers in Plan 9

[erik quanstrom <quanstro@quanstro.net>]

> Hello:
> I've been using Inferno and Plan 9 for almost a year. I certainly love
> Plan 9's ideas and concepts, and I'd be glad to finally move forward
> and leave Unix behind, but for now it is imposible for me, since my
> work does not allow me this (I do data analysis for some physics
> experiment using Cern's ROOT).
> Anyway, I've always wanted to learn to write drivers and I did try it
> a few years ago, using NetBSD, but I could not find time to complete
> the task, so I leaved it unfinished. I want to start again, but this
> time using Plan 9. So, I want to ask you for some pointers about how
> doing this. Please, bear in mind, that I am a complete newbie when it
> comes about writing drivers.
> Saludos

a few thoughts from inexperience

0.  pick something you want to use.
1.  you must have a datasheet.  reading other drivers for the same
h/w can be very misleading before you're done.
2.  implement as few features as you need to get the hardware
working for your purposes.  it's likely the other stuff will never
be needed,
3.  set up an whole plan 9 environment which can pxeboot
your target machine.  if you're like me, you'll be rebooting
quite a bit.
4,  this is still true
	The most effective debugging tool is still careful thought,
	coupled with judiciously placed print statements.
		-Kernighan, 1978

- erik