strange scsi/CAM related dmesg output

Andriy Gapon avg at
Fri Jun 18 17:28:52 UTC 2010

on 18/06/2010 18:18 mdf at said the following:
> On Fri, Jun 18, 2010 at 8:11 AM, Alexander Best
> <alexbestms at> wrote:
>> On Mon, Jun 7, 2010 at 3:57 PM, John Baldwin <jhb at> wrote:
>>> It can happen because the print buffer size thing is not line-buffered, it is
>>> printf-invocation buffered.
>> hmmm...can this somehow be fixed? i'm not sure this is specific to
>> scsi/cam. the other day i bootd my system and almost all of the dmesg
>> output was displayed incorrectly. would increasing PRINTF_BUFR_SIZE
>> from 128 to lets say 512 or 1024 solve the issue?
> I think what jhb meant was that we could look for the '\n' and flush
> to console there, instead of waiting for the end of the buffer.  This
> would perhaps have more interleaved full lines, but likely fewer
> interleaved partial lines.

Not sure if it's relevant here, but want to point out that writing to kernel
msgbuf is char-by-char, so any kind of interleaving is possible there and
PRINTF_BUFR_SIZE is irrelevant to that.

Andriy Gapon

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