>Number: 177217
>Category: conf
>Synopsis: rc.d/ddb -- squelch warning when ddb_enable=yes but DDB
>missing from kernel
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Mar 22 01:20:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator: Jeremy Chadwick
>Release: FreeBSD 9.1-STABLE amd64
>Organization:
>Environment:
System: FreeBSD icarus.home.lan 9.1-STABLE FreeBSD 9.1-STABLE #0 r248403: Sat
Mar 16 20:33:01 PDT 2013
r...@icarus.home.lan:/usr/obj/usr/src/sys/X7SBA_RELENG_9_amd64 amd64
>Description:
If a user has ddb_enable="yes" in rc.conf, but their kernel is
lacking "options DDB" and friends, then the following message is
shown during boot:
/etc/rc.d/ddb: WARNING: failed precmd routine for ddb
The reason is that returning 1 from inside of precmd causes rc.subr
to emit the above warning. Returning 0 would cause rc.subr to
continue on and try to run /sbin/ddb, which emits even more errors.
IMO, the simplest way to solve this dillema is to use "exit 1" and
bail out of the rc.d script ASAP; some other rc.d scripts use this
method as well.
To make this fact clearer to future committers/readers, I added
an explanation comment. I also added use of $SYSCTL_N to be
consistent with other scripts.
I should note I did try getting rid of the precmd stuff and instead
making a ddb_start() routine + doing the necessary magic, but this
induces all sorts of edge cases/nuances relating to required_files
and command_args and some other things. exit 1 just seems easier.
If someone has a better/cleaner method, I'm happy to test such.
>How-To-Repeat:
1. Set ddb_enable="yes" in rc.conf on a system lacking DDB support
in the kernel
2. Run "/etc/rc.d/ddb start"
>Fix:
Patch is below, and will be available at the following URL one I
get a PR number:
http://jdc.koitsu.org/freebsd/{prnum}/
Verified as working on stable/9 (r248403).
Index: etc/rc.d/ddb
===================================================================
--- etc/rc.d/ddb (revision 248604)
+++ etc/rc.d/ddb (working copy)
@@ -19,8 +19,11 @@ stop_cmd=":"
ddb_prestart()
{
# Silently exit if ddb is not enabled
- if [ -z "`sysctl -Nq debug.ddb.scripting.scripts`" ]; then
- return 1
+ # NOTE: exit is needed here, not return, else rc.subr emits
+ # a "failed precmd routine" warning when ddb_enable="yes" is
+ # used on a system which lacks DDB support in the kernel.
+ if [ -z "`$SYSCTL_N -q debug.ddb.scripting.scripts`" ]; then
+ exit 1
fi
}
>Release-Note:
>Audit-Trail:
>Unformatted:
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