linux-kernel - Re: Kernel Freeze with American Megatrends BIOS

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Date:   Tue, 30 Aug 2016 19:37:22 +0200
From:   Roland Singer <roland.singer@...ertbit.com>
To:     Emil Velikov <emil.l.velikov@...il.com>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, linux-pci@...r.kernel.org,
        "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
        ML dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-acpi@...r.kernel.org, imirkin@...m.mit.edu
Subject: Re: Kernel Freeze with American Megatrends BIOS

I am running 4.7.2, but I also just tried the 4.8.0-rc4 mainline kernel.
The result is the same. There is no difference if bbswitch of acpi_call
is used. However I noticed following:

1. The nouveau driver is broken in both kernel version and is responsible
   for the freezes while gathering power state information with bbswitch.
   Sometimes while shutting the system down, everything except the LCD
   screen is switched off. This only happens with nouveau.
   I noticed following error log messages:

   kernel: nouveau 0000:01:00.0: fb: 6144 MiB GDDR5
   kernel: nouveau 0000:01:00.0: priv: HUB0: 10ecc0 ffffffff (1e40822c)
   kernel: nouveau 0000:01:00.0: DRM: VRAM: 6144 MiB
   kernel: nouveau 0000:01:00.0: DRM: GART: 1048576 MiB
   kernel: nouveau 0000:01:00.0: DRM: Pointer to TMDS table invalid
   kernel: nouveau 0000:01:00.0: DRM: DCB version 4.1
   kernel: nouveau 0000:01:00.0: DRM: Pointer to flat panel table invalid

2. -> Boot with nouveau module loaded
   -> switch off the discrete GPU with bbswitch or acpi_call
   -> start X11
   -> obtaining power state with bbswitch freezes the system
   -> or working with the system for some minutes freezes the system

3. -> Boot with nouveau module blacklisted
   -> switch off the discrete GPU
   -> start X11
   -> system immediately freezes

4. -> Boot with nouveau module blacklisted
   -> switch off the discrete GPU
   -> start Wayland
   -> system runs - Note: I tried this for couple of days with 4.6 and 4.7 mainline
                          and the system freezed randomly after some time.
                          However I have to test if this is still present with 4.7.2
                          and 4.8 mainline. Right now it seams to be fine.
   -> running Xwayland (does not depend on the GPU power state) kills performance!
      the system freezes for several seconds...
      So working with Wayland is also no solution.

My conclusion:

1. Nouveau has couple of problems with GTX 9** M Nvidia GPUs.
   I would love to help here.

2. X11 is just broken and is not capable to start the graphical session
   if the nvidia GPU is not handled by any video driver (kernel module).
   Even forcing X11 to ignore the discrete GPU doesn't help.

   Setting the command line arguments to:

     acpi_osi=! acpi_osi="Windows 2009"

   fixes the issues with X11 but other things break...
   What the hell is going on?! :/

Am 30.08.2016 um 17:48 schrieb Emil Velikov:
> On 30 August 2016 at 16:25, Roland Singer <roland.singer@...ertbit.com> wrote:
>> I tried these scenarios:
>>
>> 1. Booted the system without the bbswitch module. The nouveau module
>>    was loaded and is responsible for the power management of the GPU.
>>    The graphical session freezes after some minutes...
>>
>> 2. Booted the system without bbswitch and with nouveau blacklisted.
>>    Manually loaded bbswitch to switch off the discrete GPU.
>>    Same freeze after a while or by explicitly obtaining the GPU state.
>>
>> Is there a possibility to switch off the discrete card without bbswitch?
>> If this is possible, then I could test this without nouveau and bbswitch
>> at all. If the system hangs, then it is not the video driver nor bbswitch.
>>
> As Ilia mentioned acpi_call should do it. You can also check with the
> nouveau/bbwswitch code to see which ones they use in your case and
> bash it manually. It might be that the 'wrong one' gets used thus
> things going horribly wrong.
> 
> Regards,
> Emil
>