Update: it seems hotplug/coldplug is the culprit.

If I disable everything, there is no hum. If I re-enable coldplug
(COLDPLUG="yes"), then the hum re-appear.

What about coldplug could be causing problems? Where should I go from here
to solve this problem?

On Sun, Mar 27, 2011 at 6:31 PM, Colleen Josephson <cjoseph@mit.edu> wrote:

> I had a question related to the amd64 minimal livecd.
>
> What exactly is happening at the "Unpacking firmware" stage of the boot
> process?
> Is there a way to find out exactly what firmware is being loaded? Or a way
> to boot without loading the firmware?
>
> Why? It is a somewhat strange reason. I am having issues with a
> high-pitched hum coming from the audio jacks (occurs on both MB sound and a
> creative sound card)
> I have a very nice sound system (a sound board, studio monitors...I am an
> audio hobbyist), and no other system has these problems, so I am relatively
> sure that it is not the speakers/cables.
>
> I have been booting from the liveCD, and I have pinpointed the point at
> which the hum starts to something near the *Unpacking firmware stage.
> I realize this is somewhat esoteric, but it renders my system almost
> useless, and would greatly appreciate any input.
>
> I did interactive mode. The interactive mode only prompts for some of the
> items. Among the items it does not prompt for is the firmware unpacking. It
> just goes and does it.
>
> --
> Colleen Josephson
> Dept. of Electrical Engineering and Computer Science
> Massachusetts Institute of Technology
> Class of 2013
>



-- 
Colleen Josephson
Dept. of Electrical Engineering and Computer Science
Massachusetts Institute of Technology
Class of 2013