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Date:      Sat, 24 Dec 1994 16:42:52 -0500 (EST)
From:      Peter Dufault <dufault@hda.com>
To:        markd@grizzly.com (Mark Diekhans)
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Kernel boot flags
Message-ID:  <199412242142.QAA22945@hda.com>
In-Reply-To: <199411301757.JAA02139@Grizzly.COM> from "Mark Diekhans" at Nov 30, 94 09:57:41 am

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Mark Diekhans writes:
> 
> 
> I am unable to find any documentation of the flags that can be specified
> at boot time.  Any pointers to where they are documented?

The boot flags are defined in /usr/include/sys/reboot.h, and some are set up
in boot.c in the booter.  With the flags that boot.c reads you have:

-a RB_ASKNAME	0x01	/* ask for file name to reboot from */
-s RB_SINGLE	0x02	/* reboot to single user only */
   RB_NOSYNC	0x04	/* dont sync before reboot */
-b RB_HALT		0x08	/* don't reboot, just halt */
   RB_INITNAME	0x10	/* name given for /etc/init (unused) */
-r RB_DFLTROOT	0x20	/* use compiled-in rootdev */
-d RB_KDB		0x40	/* give control to kernel debugger */
   RB_RDONLY	0x80	/* mount root fs read-only */
   RB_DUMP		0x100	/* dump kernel memory before reboot */
   RB_MINIROOT	0x200	/* mini-root present in memory at boot time */
-c RB_CONFIG	0x400	/* invoke user configuration routing */
-v RB_VERBOSE	0x800	/* print all potentially useful info */

Once the kernel is booted control is transferred to the routines
in /usr/src/sys/i386/i386 that interpret the flags.

I only use -s and -d, so I'm not sure how well the rest of these things
work.

Peter

-- 
Peter Dufault               Real Time Machine Control and Simulation
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dufault@hda.com             Fax:   508 433 5267
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