Regression: drm: Lobotomize set_busid nonsense for !pci drivers (a325725633c2)

[Laszlo Ersek]

On 09/30/16 16:59, Hans de Goede wrote:
> Hi,
> 
> On 30-09-16 16:51, Laszlo Ersek wrote:
>> On 09/30/16 12:35, Hans de Goede wrote:
>>
>>> Attached are 2 patches against the xserver which should fix this,
>>> please give them a try.
>>
>> Sorry about the delay.
>>
>> The patches don't seem to fix the issue for me. Please see the Xorg log
>> attached.
>>
>> I tested the patches as follows. Given that my bisection had been done
>> in a Fedora 24 guest, using
>>
>>   xorg-x11-server-1.18.4-4.fc24
>>   http://koji.fedoraproject.org/koji/buildinfo?buildID=794494
>>
>> I now rebuilt the guest kernel exactly at the failing commit (a325725
>> "drm: Lobotomize set_busid nonsense for !pci drivers"), and first
>> reproduced the issue with the above X server.
>>
>> Then, I ported your patches to "xorg-server-1.18.4" (using the upstream
>> xserver tree), and rebuilt the Fedora package with the backport. For the
>> backport, I had to cherry-pick the following two patches from master
>> first:
>>
>> 1 ca8d88e50310 xfree86: recognize primary BUS_PCI device in
>>                xf86IsPrimaryPlatform()
>> 2 ea91db4b8331 config: fix GPUDevice fail when AutoAddGPU off + BusID
>>
>> This way your patches applied cleanly. (Cherry pick #1 above is actually
>> necessary for semantics, while cherry pick #2 is needed for a clean
>> context only, and has no impact for this test.)
>>
>> That is, in total, I added the following four patches to the Fedora 24
>> package:
>>
>> 1 xfree86: recognize primary BUS_PCI device in xf86IsPrimaryPlatform()
>> 2 config: fix GPUDevice fail when AutoAddGPU off + BusID
>> 3 xfree86: Make adding unclaimed devices as GPU devices a separate step
>> 4 xfree86: Try harder to find atleast 1 non GPU Screen
>>
>> You can find the scratch build that I used for testing here:
>>
>>   xorg-x11-server-1.18.4-4.hans_bz1366842_2.fc24
>>   http://koji.fedoraproject.org/koji/taskinfo?taskID=15875087
>>
>> Another reason I used F24's X server as basis, rather than upstream
>> HEAD, is that Fedora 24 is pretty young, and it's already on kernel
>> 4.7.4, and I believe it will soon move to kernel 4.8, without
>> (necessarily) rebasing its X server package to upstream. IOW the kernel
>> upgrade to 4.8 will break X in Fedora 24 too, and then I expect the
>> Fedora X maintainers would have to cherry pick those two patches as
>> dependencies just the same.
>>
>> To summarize, the patches don't seem to help. I shall nonetheless thank
>> you for spending your Friday on this!
> 
> Hmm, do you have a xorg.conf file lying around somewhere, the message
> about the xserver not being able to find an entry for screen 0 does
> not make sense ...

Good catch, I actually had two files under "/etc/X11/xorg.conf.d/":

* "00-keyboard.conf", from package "systemd-229-13.fc24.x86_64", with
contents

------------
# Read and parsed by systemd-localed. It's probably wise not to edit
this file
# manually too freely.
Section "InputClass"
        Identifier "system-keyboard"
        MatchIsKeyboard "on"
        Option "XkbLayout" "us"
EndSection
------------

* "01-resolution.conf", which I had created, in order to set the
preferred display resolution:

------------
Section "Screen"
  Identifier "Default Screen"
  Device     "Default Device"
  Monitor    "Default Monitor"
EndSection

Section "Device"
  Identifier "Default Device"
  Driver     "modesetting"
EndSection

Section "Monitor"
  Identifier "Default Monitor"
  Option     "PreferredMode"   "640x480"
# Option     "PreferredMode"   "1440x900"
EndSection
------------

I removed these files now, and repeated the test. Again, the X server
wouldn't start, but I think the log file looks a bit different now.
Attached.

> Anyways, Monday is another day we can look at this ...

Sure; many thanks!
Laszlo

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