kern/119202: [patch] Add generic support for disabling devices

[Peter Jeremy]

>Number:         119202
>Category:       kern
>Synopsis:       [patch] Add generic support for disabling devices
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Dec 31 21:00:02 UTC 2007
>Closed-Date:
>Last-Modified:
>Originator:     Peter Jeremy
>Release:        FreeBSD 6.3-PRERELEASE amd64
>Organization:
n/a
>Environment:
System: FreeBSD turion.vk2pj.dyndns.org 6.3-PRERELEASE FreeBSD 6.3-PRERELEASE #31: Wed Dec 26 09:23:54 EST 2007 root at turion.vk2pj.dyndns.org:/usr/obj/usr/src/sys/turion amd64

>Description:
	FreeBSD supports a device.unit.disabled boot variable but this
	is only supported for some devices.  By adding the test into
	the generic device probing code, it is possible to disable any
	device.

>How-To-Repeat:
	Code inspection.
>Fix:
Index: sys/kern/subr_bus.c
===================================================================
RCS file: /usr/ncvs/src/sys/kern/subr_bus.c,v
retrieving revision 1.184.2.6
diff -u -r1.184.2.6 subr_bus.c
--- sys/kern/subr_bus.c	5 Nov 2007 11:49:44 -0000	1.184.2.6
+++ sys/kern/subr_bus.c	25 Dec 2007 20:41:41 -0000
@@ -1722,7 +1722,10 @@
 			resource_int_value(dl->driver->name, child->unit,
 			    "flags", &child->devflags);
 
-			result = DEVICE_PROBE(child);
+			if (resource_disabled(dl->driver->name, child->unit))
+				result = ENXIO;
+			else
+				result = DEVICE_PROBE(child);
 
 			/* Reset flags and devclass before the next probe. */
 			child->devflags = 0;
@@ -1805,7 +1808,8 @@
 			 * A bit bogus. Call the probe method again to make
 			 * sure that we have the right description.
 			 */
-			DEVICE_PROBE(child);
+			if (!resource_disabled(best->driver->name, child->unit))
+				DEVICE_PROBE(child);
 #if 0
 			child->flags |= DF_REBID;
 #endif
>Release-Note:
>Audit-Trail:
>Unformatted: