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From: John Baldwin <jhb@freebsd.org>
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Date: Thu, 22 Mar 2012 08:13:12 -0400
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	(bigwig.baldwin.cx); Thu, 22 Mar 2012 10:09:24 -0400 (EDT)
Cc: Alexander Best <arundel@freebsd.org>
Subject: Re: still issues with unreadable dmesg output on SMP systems
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On Thursday, March 22, 2012 6:10:41 am Alexander Best wrote:
> hi there,
> 
> a few years ago there were huge issues with SMP and dmesg output, where
> messages from various drivers were output to /dev/ttyv0 without any timing,
> which caused a lot of unreadable lines.
> 
> this was fixed and almost all of the dmesg lines i see now look similar to
> dmesg on a non-SMP aware kernel. however there still seems to be an issue
> within the cd(4) driver. maybe somebody could fix the driver output to match
> the drivers, where the dmesg output looks correct (da(4), ada(4), ...).

s/fixed/mostly worked around/

The problem is that the work around isn't perfect.  The root cause is still 
not fixed.  avg@ has some ideas on better ways to handle this, but it is a bit 
tricky to get this right since we also dont' want printfs to be delayed too 
much (and to fix this perfectly requires buffering printf output).

-- 
John Baldwin