Increasing system message buffer size

[Dan Nelson]

In the last episode (Mar 21), Andrew Robinson said:
> I'm working on a problem that would benefit from verbose logging of
> the boot process.  Unfortunately my logging is SO verbose that it
> fills up the available system buffer.  I'm trying to figure out how
> to change the buffer size.  I'm on 5.3 Stable.
> 
> It looks like one way to do it might be to recompile the kernel, with 
> 
> options		MSGBUF_SIZE=65536
> 
> set.  Is that the best way?  If so, what is the default size of the
> buffer?  I checked NOTES in /usr/src/sys/i386/conf but couldn't find
> any reference to it.

Yes, that's the only way to do it.  It might be possible to convert it
into a tunable (which would let you set it in /boot/loader.conf), but I
don't know how early in the boot process tunables are available.  The
default is 32768 (see /sys/sys/msbguf.h).

-- 
	Dan Nelson
	dnelson at allantgroup.com