Patch ID	: P94042142
Summary		: Fix for frequent SCSI bus resets
Status		: Mandatory
Date		: 04/21/94
Release		: OS 4.1C
Architectures	: all
Affected bugs	:
	B940310001
	B940411001

Changed files	:
	sys/kbus/subr.s (delta 1.9)
	sys/kapdev/si.c (delta 1.6)

Problem Description:
This patch fixes a problem which leads to frequent SCSI bus resets on some 
50 MHz Series 6 systems. The problem may also occur on 33 MHz systems, but
this is much less likely. 

A typical message fragment follows:

si0: si_reset: asr c0<INT,LCI>: ltarg.lun 0.0: lcode(asr 00 cmd 00 ist 00 cp 00)si0: dump of WD regs: before reset
OID :87 CR  :8d TPR :3e C0  :08 C1  :01 C2  :1b C3  :5b C4  :10
C5  :00 C6  :00 C7  :00 C8  :10 C9  :00 C10 :00 C11 :00 TLUN:00
CP  :00 STR :2c TCRH:00 TCRM:20 TCRL:00 DID :00 SID :aa IST :80
CMD :08 DATA:80 QTAG:ff
sd2: read: reset:..retry
sd3: read: reset:..retry
sd0: read: reset:..retry
sd1: write: check: unit attention(06): power_on/reset(29):..retry
sd0: read: check: unit attention(06): power_on/reset(29):..retry
sd2: read: check: unit attention(06): power_on/reset(29):..retry
sd3: read: check: unit attention(06): power_on/reset(29):..retry
sd0: recovered
sd2: recovered
sd3: recovered
sd1: recovered
