X server fails to start on MacBookPro9,1 with hybrid Intel/Nvidia graphics: no screens found

[Adam Dingle]

I have a MacBookPro9,1, which has both an integrated Intel HD Graphics 4000 controller and a discrete Nvidia GeForce GT 650M. I want to disable the Nvidia graphics and boot using Intel only, since I don't need the Nvidia chip's capabilities and it shortens battery life (and makes suspend/resume not work; see bug #1084960). But when I blacklist the Nouveau driver and reboot using the Intel driver only, the X server fails to start: it reports "no screens found" and crashes.

I'm booting using EFI rather than BIOS; not sure whether that's relevant.

I'll attach the X server log and the dmesg log. Just let me know if there's any other information I can provide.

[Adam Dingle (adam-yorba)]

Note that in the X log I attached the X server still loads the Nouveau X driver nouveau_drv.so. As I mentioned I blacklisted the kernel driver, so I assume that the X driver can't do anything. Still, maybe I should repeat this experiment with the Nouveau X driver uninstalled.

[Adam Dingle (adam-yorba)]

OK, I uninstalled the Nouveau X driver, blacklisted the Nouveau kernel driver and rebooted. As I suspected, it made no difference: the X server still failed to start. I'll attach the Xorg.0.log from this time around.

[Chris Wilson (ickle)]

Looks like there is still a mux involved - a hardware switch between the GPUs and the screen. That is preventing the igfx from detecting any connectors, and from there it looks like things go south. (But as far as I am aware, that should not actually prevent the driver from being loaded - since there are configurations where we support no connectors.)

[Chris Wilson (ickle)]

No... The issue is that X considers the nvidia GPU still as the primary and so loads VESA for it (which fails) and Intel as the secondary GPU driver.

So the secret will be to set the mux to make Intel the primary/boot GPU and connected to the displays.

[Adam Dingle (adam-yorba)]

Ah. And who should be setting the mux in that way? The Intel X driver? The Intel kernel driver? Some other component?

[Chris Wilson (ickle)]

vgaarb and the mux driver

[Adam Dingle (adam-yorba)]

Ah. Is this something that you can work on (and are willing to), or should I refile this as a bug in those kernel drivers to bring this to the attention of others?

[Chris Wilson (ickle)]

I spoke to Dave Airlie and he is aware of this issue, but hasn't a clue how to proceed given the dearth of documentation Apple (or their component suppliers) provides - though he succeeded in getting the eDP lit up on occasion. It is not a task I am going to do myself. You can always ask if Maarten Lankhorst or Robert Sarvatt have the opportunity to take a look at the hardware.

[Launchpad Janitor (janitor)]

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

[penalvch (penalvch)]

Adam Dingle, thank you for reporting this and helping make Ubuntu better.

Could you please boot into a working environment of Ubuntu (i.e. without disabling the nvidia card), and run the following command once from a terminal by ensuring you have the package xdiagnose installed, and that you click the Yes button for attaching additional debugging information:
apport-collect -p xorg 1190806

[Adam Dingle (adam-yorba)]

I'm no longer attempting to run Ubuntu on a MacBook, so I have no way to test this right now. Sorry! We can just close this if you like.

[penalvch (penalvch)]

Adam Dingle, this bug report is being closed due to your last comment https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1190806/comments/14 regarding you aren't running Ubuntu on the computer. For future reference you can manage the status of your own bugs by clicking on the current status in the yellow line and then choosing a new status in the revealed drop down box. You can learn more about bug statuses at https://wiki.ubuntu.com/Bugs/Status. Thank you again for taking the time to report this bug and helping to make Ubuntu better. Please submit any future bugs you may find.