Re: [9fans] usb/usbaudio and output speed?

[Dan Cross <cross@math.psu.edu>]

> If you can reliably make ps hang, please tell me how.
> I've seen it happen only three times in the last three
> months, and there's never enough information to figure
> out exactly how it got into the state.

Okay, I can reliably (sic) make ps et al hang.  This is on an IBM
Thinkpad T21 aquired circa December, 2000.  The only USB device
connected to it at the time was a Xitel HiFi-LINK (USB audio).  It was
plugged into City power, and there was an audio CD (Rachmaninoff piano
concertos, I believe; I doubt that's relevant, but you never know) in
the CD-ROM drive at the time.  Here's what I did:

I booted up and logged in as none to minimize potential problems due to
my local environment; hopefully this should make this repeatable for
others.  My termrc is more or less what's in the distrubtion, modulo
some minor changes setting environment variables and the like, and one
``if ...'' that detects what network I'm using (and invokes ipconfig
accordingly) based on plan9.ini, so that should add minimal noise to
the mix.  I did an ``aux/vga -l $vgasize'' and started rio.  I swept
out a window and executed the following:

	term% usb/usbd
	term% usb/usbaudio
	term% usb/usbaudio	#  Note, invoking usb/usbaudio twice.
	term% kill usbaudio | rc

...And the last command hung.  I then swept out another window, tried
to run ps, but it also hung.  I then swept a third window, halted KFS,
and rebooted.  I repeated the experiment a couple of times to make sure
it wasn't a fluke, but each time got the same result.  I didn't have
time last night to investigate further (neither do I have time at the
moment, unfortunately).

Anyway, it seems that ps hangs pretty consistently when I do this.  Russ,
can you duplicate it?

	- Dan C.