[Klug-general] Virtualbox woes

[MacGyveR]

On Thursday 06 Mar 2008, Mike Evans wrote:
> Dan and I just had a convo on IRC but I thought I'd document the outcome
> for the benefit of everyone.  (Yes something that could go on the
> website, but not tonight, I'm tired.)
>
> Basically if you have a usb sound device plugged in at boot the chances
> are the usb sound driver will get loaded before your regular sound card
> driver.  This has the effect of pushing your sound card driver from
> number '0' to number '1'.  Of course your alsa configuration has no way
> to know that's what happened and applies all the wrong settings to
> everything.
>
> You can verify this by unplugging the USB device and rebooting and sound
> is probably restored as the sound card will be in the '0' position.
> Plug in the USB device after boot and it takes the number '1' slot and
> you're probably still good.  Reboot with it plugged in and they swap
> round again.  It would be possible to tweak your alsa configuration, but
> then it would be wrong if ever you booted without the usb device.
>
> The answer for me was to dictate the order of the device numbers in the
> modprobe.conf file where I have the following lines:
>
> alias snd-card-0 snd-ens1371
> options snd-ens1371 index=0
> options snd_usb_audio index=1
>
> As a result of this my sound card with the ens1371 driver is
> consistently in position 0, and the webcam with its built in microphone
> is in position 1.
>
> For some reason the speaker applet thingy on my gnome taskbar is still a
> little confused as it now always shows that the device is muted, but I
> get sound just fine.  I'll try to sus that out one day.
>
> Incidentally there is a similar problem with the on-board modem driver
> module.  Even if you don't use it, if your distro ships with it it will
> probably load before the main sound card driver and then nothing works.
>   (You get some message about a semaphore not being ready in dmesg.)
> Ubuntu doesn't install the modem to sound card driver out of the box -
> but if you click on the 'install restricted drivers' bit for it then you
> will be in the same position as that's what happened to me on my laptop.
>   I believe there is a way to get them to load in the other order, but I
> found the web page once for it and can't track it down again.  The
> answer for me on this one has been to blacklist the modem bit as I don't
> need it right now.  The blacklisting is done using a similar mechanism
> in the modprobe file(s) and if anyone needs it I'll look it up on my
> laptop.
>
> I had unpredictable sound card behaviour for ages before I discovered
> this stuff.  You can find it on various howtos and forums, but not all
> in one place.
>
> The answer lies in doing an lsmod with the usb device plugged in at boot
> and one with it not there.  Compare the two and the additional modules
> are what's causing the problem.  You just have to figure out what to do
> about it.
>
> MikeE
>
> Dan Attwood wrote:
> > after the discussion at the last meeting about virtualbox I decided to
> > give usb support another go.
> >
> > I followed the various info on spodes site and on several other
> > resources and soon add usb support running and was was happily mixed
> > some banging tunes on with my usb mixer in propellerheads reason running
> > in seamless mode on windows xp.
> >
> > and then I rebooted
> >
> > oh dear
> >
> > Now I get a message at boot time telling me that alsa failed to start.
> > Then when I get into gnome sound in totem doesn't work - the volume
> > slider is even greyed out. Sound in amarok is fine though. To add insult
> > to injury the usb support stopped work as well.
> >
> > Anyone got any bright ideas?
> >
> >
> > ------------------------------------------------------------------------
> >
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> > Kent at mailman.lug.org.uk
> > https://mailman.lug.org.uk/mailman/listinfo/kent
>
> _______________________________________________
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> Kent at mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/kent

this is the sort of thing udev should fix you may be able to add some rules 
in:

/etc/udev/rules.d

as you can set rules for multiple network cards and cd rom drives

as a last resort you could just compile your *primary* sound card into the 
kernel and leave others as a module, this way it will always be loaded first.

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