Increasing the DMESG buffer....

Gary Palmer gpalmer at
Thu Nov 22 22:49:17 UTC 2012

On Thu, Nov 22, 2012 at 02:14:59PM -0800, Kevin Oberman wrote:
> On Thu, Nov 22, 2012 at 2:05 PM, Adrian Chadd <adrian at> wrote:
> > On 22 November 2012 06:30, Alexander Motin <mav at> wrote:
> >
> >> Neither ICH, nor any other driver I know have amount of information
> >> comparable to what HDA hardware provides. So the analogy is not good.
> >> Respecting that most CODECs have no published datasheets, that information
> >> is the only input for debugging.
> >>
> >> snd_hda also uses hw.snd.verbose=3. But it is used for even deeper driver
> >> debugging. It also enables a lot of debugging in sound(4), that can be too
> >> verbose for HDA debugging.
> >>
> >> I will recheck again how can it be reorganized, but I think that the real
> >> problem is not in HDA. We need some way to structure and filter the output.
> >
> > I honestly would like to just see it spat out using a userland tool,
> > rather than having the kernel print that level of topology data out.
> >
> > It's highly unlikely that a topology problem is going to cause a
> > system to not boot, right? So the kernel itself doesn't need to be
> > able to spit that data out.
> Maybe I'm missing something, but the data needed to adjust HDAC is
> available from 'sysctl dev.hdaa'. I have not looked at the verbose
> output in quite a while, but I think it is mstly or entirely hte
> information in that and 'sysctl dev.hdac'. I never needed to look
> elsewhere to get mine set up properly.
> Also, isn't the entire verbose boot captured in /var/run/dmesg?

Only if the message buffer hasn't overflowed before the utility runs to
populate the file


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