misc/120914: [patch] proposed fix to rc.shutdown to turn off the mixed buffer messages with an rc.conf tuneable

[Dominic Fandrey]

>Number:         120914
>Category:       misc
>Synopsis:       [patch] proposed fix to rc.shutdown to turn off the mixed buffer messages with an rc.conf tuneable
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Wed Feb 20 19:30:02 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Dominic Fandrey
>Release:        RELENG_7
>Organization:
private
>Environment:
FreeBSD mobileKamikaze.norad 7.0-PRERELEASE FreeBSD 7.0-PRERELEASE #3: Wed Feb 13 17:52:28 CET 2008     root at mobileKamikaze.norad:/usr/obj/HP6510b/amd64/usr/src/sys/HP6510b  amd64
>Description:
On multicore machines several buffers simultaneously write to the screen and produce unreadable output.
>How-To-Repeat:
Apply the patch and add

shutdown_clean_enable="YES"

to your /etc/rc.conf.
>Fix:
--- rc.shutdown	2008-02-20 19:28:45.000000000 +0100
+++ /etc/rc.shutdown	2008-02-20 19:59:03.000000000 +0100
@@ -43,10 +43,21 @@
 PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin
 export HOME PATH
 
+# The next three lines belong into /etc/defaults/rc.conf.
+shutdown_clean_enable="NO"	# Set to YES to stop all but the first CPU
+				# core to prevent mixed buffer output
+				# upon shutdown.
+
 . /etc/rc.subr
 
 load_rc_config 'XXX'
 
+# Fall back to single core mode to guarantee clean output.
+if checkyesno shutdown_clean_enable; then
+	bitmask="$(jot -s '' -b1 $(expr $(sysctl -n hw.ncpu) - 1))0"
+	sysctl machdep.hlt_cpus=$bitmask
+fi
+
 # reverse_list list
 #	print the list in reverse order
 #


>Release-Note:
>Audit-Trail:
>Unformatted: