What causes ``panic: ataintr: read/ident'' in 9DOS?

[presotto@plan9.att.com presotto@plan9.att.com]

fst@@claircom.com writes:

	Dear Rosanne Rosanadanna,

	I am having trouble installing the 3 dis[ck] demo set; This is a
	Toshiba T2450CT laptop (75MHz i486DX4, 8MB, TFT VGA, 320MB IDE, and
	AccuPoint).

	The problem occurs on the first dis[ck] when B.COM is invoked on the
	A: drive.  B.COM seems to find, load, and run 9DOS.  Here is what it
	says:

	1269 free pages, 5076K bytes, swap 32596K, highwater 252K, headroom 312K
	CPU is a 74 MHz IntelDX4 (cpuid: ax 480 dx 3)
	pcmcia controller0 is a 1 slot Cirrus Logic PD6710
	fs...time...panic: ataintr: read/ident
	exiting

	Any ideas?

We took this off line.  After a few go arounds we figured out that the
drive was sending us ident info that Plan 9 didn't understand.  We made
the driver more robust in the face of rediculous info.  The diffs are
in http://plan9.att.com/plan9/errata/devata.c.diff.  I also made a
version of disk1, ftp://plan9.att.com/plan9/pcdist/disk1.2 with the
changes included.