Path: utzoo!utgpu!water!watmath!onfcanim!dave
From: dave@onfcanim.UUCP (Dave Martindale)
Newsgroups: comp.bugs.4bsd
Subject: Autoconf bug causes controller to be configured twice
Message-ID: <15563@onfcanim.UUCP>
Date: 3 Mar 88 01:21:59 GMT
Reply-To: dave@onfcanim.UUCP (Dave Martindale)
Organization: National Film Board / Office national du film, Montreal
Lines: 43

Subject: Autoconf bug causes controller to be configured twice
Index:	sys/vax/autoconf.c

Description:
	The loop that configures UBA mass-storage controllers does not
	mark the chunk of UBA space occupied by the controller as "in use".
	This can result in the same physical piece of hardware being
	configured twice, as two different controllers.

Repeat-By:
	Install two TS-11's (or any other tape or disk controller) on
	the Unibus, with controller 0 at the standard address.  Have
	controller 1 fail.  Reboot the system.  The autoconf code will
	correctly configure controller 0, then try controller 1.
	The driver's probe routine fails, so the autoconf code then
	tries the list of standard addresses compiled into the driver.
	It probes controller 0 again, succeeds, and installs a new
	interrupt vector over top of the old one.

	Try using a driver on controller 0.  The interrupt appears to
	come from controller 1, and the process is hung until the next boot.
	Attempts to access drives on controller 1 successfully use the
	drive with the same drive number on controller 0.

Fix:
	The "ualloc" array is supposed to keep track of already-configured
	controllers, to prevent the above from happening.  The loop which
	deals with UBA devices sets it, the loop for controllers doesn't.
	Add the following code:

*** /tmp/,RCSt1000158	Wed Mar  2 20:06:07 1988
--- autoconf.c	Wed Mar  2 19:45:02 1988
***************
*** 686,691 ****
--- 686,693 ----
  			continue;
  		}
  		printf("vec %o, ipl %x\n", cvec, br);
+ 		while (--i >= 0)
+ 			ualloc[ubaoff(addr+i)] = 1;
  		um->um_alive = 1;
  		um->um_ubanum = numuba;
  		um->um_hd = &uba_hd[numuba];