Mir does not support multiple GPUs/cards simultaneously

[Nick Dedekind]

I have a Lenovo laptop which has a hybrid graphics chipset.
When I have a monitor connected to the displayport, the displayport monitor is on /dev/dri/card0 while the LVDS (integrated lcd) is at /dev/dri/card1.

Our kms implementation only supports a single device; that which is found first with a valid connection. We need to support multiple devices.

[Cemil Azizoglu (cemil-azizoglu)]

bumping the priority due to :

<kgunn> camako: bregma so multimonitor is getting to be hot, is there anyway we could raise priority for this one
<kgunn> https://bugs.launchpad.net/mir/+bug/1598243
 actually effects a few people on unity team

[Daniel van Vugt (vanvugt)]

Whoops. Technically this is not a multimonitor bug. It's about multiple GPUs/cards. The dominant use case is on laptops with hybrid graphics where there are two GPUs but only one monitor.

[Daniel van Vugt (vanvugt)]

And possibly this is not an important bug at all unless you want to play games. Mir (should) still supports the primary GPU on hybrid systems just fine, and runs normally.

[Daniel van Vugt (vanvugt)]

Spoke too soon. Apparently Mir isn't so great at choosing the right GPU -> bug 1418662

[Daniel van Vugt (vanvugt)]

We'll need a little architectural overhaul to solve this. It involves having multiple different graphics drivers loaded simultaneously, allowing some to have zero outputs attached, and passing buffers between the different drivers.

[Daniel van Vugt (vanvugt)]

We discussed doing a quick fix for 1.0 that supports only the multiple Mesa devices case. If we do that then this bug still needs to stay open for the main case of multiple different devices/drivers such as Nvidia+Intel (not nouveau).

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.