kern/46539: Kernel messages: sysctl to change verbosity

[nathanialsloss%yahoo.com.au@localhost]

>Number:         46539
>Category:       kern
>Synopsis:       Kernel messages: sysctl to change verbosity
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Mon Jun 04 06:00:01 +0000 2012
>Originator:     Nat Sloss
>Release:        NetBSD Current 6.99.7
>Organization:
>Environment:
NetBSD beast 6.99.7 NetBSD 6.99.7 (LOCKDEBUG) #59: Mon Jun  4 13:15:47 EST 2012 
 build@beast:/usr/src/sys/arch/i386/compile/obj/LOCKDEBUG i386

>Description:
I like the splash screen feature and I boot silently to suppress kernel boot up 
messages, but I would also like to see kernel messages once booted up.
>How-To-Repeat:
Boot up silently (-z) and you then have no way to get kernel messages back on 
the console.
>Fix:
I patched init_sysctl.c to add a sysctl to alter boothowto to change kernel 
message verbosity from 0 silent to 4 debug.

So here's my patch:

Index: sys/kern/init_sysctl.c
===================================================================
RCS file: /cvsroot/src/sys/kern/init_sysctl.c,v
retrieving revision 1.189
diff -u -r1.189 init_sysctl.c
--- sys/kern/init_sysctl.c      7 Apr 2012 05:38:49 -0000       1.189
+++ sys/kern/init_sysctl.c      4 Jun 2012 05:41:24 -0000
@@ -57,6 +57,7 @@
 #include <sys/filedesc.h>
 #include <sys/tty.h>
 #include <sys/kmem.h>
+#include <sys/reboot.h>
 #include <sys/resource.h>
 #include <sys/resourcevar.h>
 #include <sys/exec.h>
@@ -145,6 +146,7 @@
 static int sysctl_kern_trigger_panic(SYSCTLFN_PROTO);
 #endif
 static int sysctl_kern_maxvnodes(SYSCTLFN_PROTO);
+static int sysctl_kern_messages(SYSCTLFN_PROTO);
 static int sysctl_kern_rtc_offset(SYSCTLFN_PROTO);
 static int sysctl_kern_maxproc(SYSCTLFN_PROTO);
 static int sysctl_kern_hostid(SYSCTLFN_PROTO);
@@ -747,6 +749,12 @@
                        SYSCTL_DESCR("Maximal number of semaphores"),
                        NULL, 0, &ksem_max, 0,
                        CTL_CREATE, CTL_EOL);
+       sysctl_createv(clog, 0, NULL, NULL,
+                      CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
+                      CTLTYPE_INT, "messages",
+                      SYSCTL_DESCR("Kernel message verbosity"),
+                      sysctl_kern_messages, 0, NULL, 0,
+                      CTL_KERN, CTL_CREATE, CTL_EOL);
 }

 SYSCTL_SETUP(sysctl_hw_setup, "sysctl hw subtree setup")
@@ -989,6 +997,72 @@
 }

 /*
+ * sysctl helper routine for kern.messages.
+ * Alters boothowto to display kernel messages in increasing verbosity
+ * from 0 to 4.
+ */
+
+#define MAXMESSAGES            4
+static int
+sysctl_kern_messages(SYSCTLFN_ARGS)
+{
+       int error, messageverbose, messagemask, newboothowto;
+       struct sysctlnode node;
+
+       messagemask = (AB_NORMAL|AB_QUIET|AB_SILENT|AB_VERBOSE|AB_DEBUG);
+       switch (boothowto & messagemask) {
+       case AB_SILENT:
+               messageverbose = 0;
+               break;
+       case AB_QUIET:
+               messageverbose = 1;
+               break;
+       case AB_VERBOSE:
+               messageverbose = 3;
+               break;
+       case AB_DEBUG:
+               messageverbose = 4;
+               break;
+       case AB_NORMAL:
+       default:
+               messageverbose = 2;
+       }
+
+       node = *rnode;
+       node.sysctl_data = &messageverbose;
+       error = sysctl_lookup(SYSCTLFN_CALL(&node));
+       if (error || newp == NULL)
+               return (error);
+       if (messageverbose < 0 || messageverbose > MAXMESSAGES)
+               return EINVAL;
+
+       /* Set boothowto */
+       newboothowto = boothowto & ~messagemask;
+
+       switch (messageverbose) {
+       case 0:
+               newboothowto |= AB_SILENT;
+               break;
+       case 1:
+               newboothowto |= AB_QUIET;
+               break;
+       case 3:
+               newboothowto |= AB_VERBOSE;
+               break;
+       case 4:
+               newboothowto |= AB_DEBUG;
+               break;
+       case 2:
+       default:                /* Messages default to normal. */
+               break;
+       }
+
+       boothowto = newboothowto;
+
+       return (0);
+}
+
+/*
  * sysctl helper routine for rtc_offset - set time after changes
  */
 static int


Note: This patch is my own work which I submit under the NetBSD license.

I would also like to ask if it is considered could NetBSD 6 be pulled up as 
this feature is very useful.

Regards,

Nat.