Subject: Re: How do I change the size of msgbuf? (dmesg buffer)
To: None <,>
From: None <>
List: tech-kern
Date: 12/10/2007 11:13:07
>On Mon Dec 10 2007 at 10:51:36 -0800, wrote:
>> Hello NetBSD kernel gurus,
>> I am in the midst of porting a driver from FreeBSD to NetBSD.  It would
>> be real helpful if I could increase the size of the DMESG buffer (msgbuf).
>> I'm building/testing under the AMD64 platform.  I found 'msgbuf_p_cnt' in
>> /usr/src/sys/arch/amd64/amd64/machdep.c which appears to be what controls
>> the size of msgbuf, but it's initialized to 0 and I don't see it ever set
>> or referenced anyplace else in the kernel!  Obviously, I'm missing something.
>You can set MSGBUFSIZE in your kernel config, e.g.:
>options         MSGBUFSIZE=262144

Thanks!  I'll give this a try.

>Then re{config,compile,boot}.
>> I even tried adding the line 'kern.msgbufsize=131000' to /etc/sysctl.conf
>> and rebooting, but the size always shows up at 16352.  What am I not seeing??
>That value is read-only, see sysctl(7).

Doh!  Thanks for pointing that out.

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