Re: weird console output

On Sat, 21 Mar 2009 14:52:59 -0400
Chuck Robey <chuckr_at_telenix.org> wrote:

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> Gary Jennejohn wrote:
> > On Fri, 20 Mar 2009 20:49:08 -0400
> > Justin Hibbits <jrh29_at_alumni.cwru.edu> wrote:
> > 
> >> On Sat, Mar 21, 2009 at 01:02:25AM +0100, Alexander Best wrote:
> >>> very often when i boot or shutdown my pc i see weird text being output to the
> >>> console. to me it seems like 2 messages are being mixed into 1 message. here's
> >>> an example:
> >>>
> >>> "WcAdR0N IaNtG : aWtIaT1N EbSuSs  o0p ttiaorng eetn a1b lleudn,  0e
> >>> xcpde0c:t  r<eHdLu-cDeTd- SpTe rDfVoDrRmAaMn cGeS.A-
> >>> H1W0ANR NJILN1G: DIAG2N>O SRTeImCo voapbtlieo nC De-nRaObMl eSdC,S Ie-x0p
> >>> edcetv irceed uc
> >>> ecdd 0p:e r3f3o.r0m0a0nMcB/es.
> >>> transfers"
> >>>
> >>> i'm running FreeBSD moshnroll 8.0-CURRENT FreeBSD 8.0-CURRENT #20 r190162M:
> >>> Fri Mar 20 19:10:47 UTC 2009     root_at_moshnroll:/usr/obj/usr/src/sys/ARUNDEL
> >>> i386, but i've also had this issue under CURRENT. maybe this issue is smp
> >>> related?
> >>>
> >>> cheers.
> >>> alex
> >> You are correct, it is smp related.  Those are two messages interlaced.  I see
> >> them often when shutting down my SMP system.
> >>
> > 
> > This quesion is asked and answered again and again.
> > 
> > Set "options PRINTF_BUFR_SIZE=128" in your kernel config.
> 
> Gary, do you know why setting it to 128 fixes things?  Is the default size 0?  I
> could see that causing things, but it's hard to believe.  I've been watching a
> long time to see a fix for this.
> 

Looking at /sys/kern/subr_prf.c, there's apparently no buffering at all
when PRINTF_BUFR_SIZE isn't defined.  The value 128 has proved itself
to be adequate based on experience since most kernel output is smaller
than that.  Its' what I and others use.

---
Gary Jennejohn