Comment 13 for bug 969489

For 12.10, we really should add a 'primary-graphics-card' event alias or abstract job that abstracts the udev complexities since that confusing condition ("drm-device-added card0 PRIMARY_DEVICE_FOR_DISPLAY=1 or stopped udev-fallback-graphics") is also semi-duplicated in other jobs:

- plymouth-splash.conf
- udev-fallback-graphics.conf

I think the "definitive" condition that becomes true when the first graphics device becomes available is:

(graphics-device-added PRIMARY_DEVICE_FOR_DISPLAY=1
    or drm-device-added PRIMARY_DEVICE_FOR_DISPLAY=1
    or stopped udev-fallback-graphics)

I agree that 'card0' seems bogus - looks like it's trying to match DEVPATH but that will never match since there is no wildcard in the expression. It should be something like the following (note the asterisk after the equals!!):

    drm-device-added DEVPATH=*card0 PRIMARY_DEVICE_FOR_DISPLAY=1

Using named variables ('name=value' as opposed to positional ones where only a *value* is given) as I've done above is *much* safer in this scenario since to use positional variables, you need to know the exact content of the corresponding udev message that the upstart-udev-bridge converts into an Upstart event.

File /lib/udev/rules.d/78-graphics-card.rules is what is modifying the udev message to add PRIMARY_DEVICE_FOR_DISPLAY=1 so I'm wondering if we can simplify the logic to be simply:

    drm-device-added PRIMARY_DEVICE_FOR_DISPLAY=1

... since udev will tag both KMS and non-KMS devices correctly.