[pulseaudio-discuss] Pulseaudio and hal deprecation/DeviceKit.

[Lennart Poettering]

On Mon, 11.05.09 22:19, Luke Yelavich (themuso at ubuntu.com) wrote:

Heya,

> For the next version of Ubuntu, the userspace hardware guys want to
> deprecate hal if not completely, then as much as possible, They've
> already started moving stuff like network manager bits away from
> hal. Given that Pulse still relies on hal somewhat heavily, I am
> wondering what the plans are regarding Pulse and the future of hal
> support/using DeviceKit etc. Since pulseaudio now uses libudev, is
> that the route that will be taken in the future?
> 
> I don't know a lot about this layer, in terms of future plans, so
> feel free to correct me if I'm wrong.

Actually I am in good contact with Kay. As you might have seen PA
0.9.15 already links against libudev in addition to libhal and even
has a dep on udev-extras (of which I maintain a few parts), I didn't 
make the full switch due to a variety of reasons:

There was the license problem: libudev used to be GPL, PA LGPL. Making
libudev a hard dep of PA would effectively downgrade it to GPL which
might be a problem for some vendors. This has been fixed now. libudev
is now LGPL.

Then only with the very latest kernel you can use libudev for
subscribing to device events without being root. And even now that
this is available I wonder if it would be OK to make PA depend on the
very latest kernel version. It might help if someone would prepare
patch for libudev that spawns a suid helper that forwards those events
on older kernels to unpriviliged processes.

Then there are still a few missing parts: the ckit integration/acl
handling is still a big void in the post-hal world. 

Also, unfortunately due to the way ALSA works we need some non-trivial
code to watch /dev/snd and wait until all device nodes of a card are
created before we try to open it. The kernel doesn't really give us an
explicit sync point at which we would know that all devices are
properly created. Kay and I mostly figured out how this should be
working but I haven't implemented it yet.

These are the biggest issues, there might be more. 

It's certainly my plan to drop HAL support completely for the F12
timeframe. Always happy about help.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4