Re: Assigning sound card to specific X display - the chroot+bind-mount way

[Arne G. G. <ar...@li...>]

* Helge Hafting
> There is a way.
> One xserver can run in its own chroot.  The two servers can have
> distinct /dev directories that way, where the two "dsp" files in the
> distinct directories have different device numbers and so
> refer to different sound devices.
> Make a copy of /dev in /chroot/dev.  In there, make sure
> "dsp" refers to the second soundcard instead of the first.
>
> On a debian system "dsp" is a symlink to "dsp0".  Change it to
> a link to "dsp1" instead.  On other systems you may have to
> do something like "mv dsp1 dsp0".
>
> Whatever the solution is, do the same for all other sound-related
> files, such as "mixer" and so on.
>
>
> Now the chroot has a customized /dev.  But what about all the
> other directories needed for normal operation, such as
> /bin, /usr, /var, /home and so on?
>
> The answer is to bind-mount them.  Bind-mount every top-level
> directory except /dev into the chroot, and you should be fine.
> Then chroot into the /chroot directory, and start the second xserver.
> (Details: man mount, search for "bind")

Using chroot for this seems a bit excessive to me.  I'd suggest
running the X-servers in separate namespaces (see bottom of
http://www.win.tue.nl/~aeb/linux/lk/lk-6.html) and then use bind mount
on a device node level to customize the different namespaces.


							Arne.