Installing drivers, need new DeviceKit method

[Richard Hughes]

Jon wants to automatically download drivers for his soundcard. The way I
envisage this happening is:

1. UDEV rule merges in PK_NEEDED_PACKAGE='alsa-firmware'
2. gnome-packagekit/kpackagekit watches DeviceKit for this key to appear
3. session triggers install if it's not already installed

Now, the udev rule can be shipped in udev-extras, or even PackageKit.
What we also have to handle is when the soundcard is installed, and the
computer boots. We need a way to enumerate all devices (of all
subsystems) and check for keys.

Do we need a EnumerateDevices() method in DeviceKit, or should
gnome-packagekit be peeking in /sys?

Richard.