still issues with unreadable dmesg output on SMP systems
John Baldwin
jhb at freebsd.org
Thu Mar 22 14:09:25 UTC 2012
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
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