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Drivers & Software

chfast
Journeyman III
Journeyman III

X server with integrated GPU

Hi,

I have a desktop computer with Intel integrated GPU card and discrete AMD card (280x). I'm using Ubuntu 15.04.

I would like to configure Xorg to load and use intel driver only and dedicate AMD card to OpenCL tasks only. Is it possible?

I tried many things:

  1. Using Xorg auto-configuration (by removing xorg.conf file) makes the Xorg to load both fglrx and intel driver and crash (enters low resolution mode).
  2. Replacing fglrx with intel driver in xorg.conf makes Xorg start. But Ubuntu enters login loop. I've seen in some places that lightdm should be also reconfigured, but I'm not sure how to do it.
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6 Replies
natasha
Elite
Elite

Re: X server with integrated GPU

Do I understand you correctly?

You have a desktop machine with integrated Intel GPU. You insert AMD PCIe card. You want to connect monitor to the Intel card and use AMD card just for OpenCL, not for graphics, don't you?

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chfast
Journeyman III
Journeyman III

Re: X server with integrated GPU

Correct.

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natasha
Elite
Elite

Re: X server with integrated GPU

Try to boot into 3-rd boot-level (without X) and execute clinfo as root. Does it see the AMD GPU? Show the result of

clinfo | grep 'Name:'

please.

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chfast
Journeyman III
Journeyman III

Re: X server with integrated GPU

I've tested both fglrx and fglrx-core only variants.

In both cases clinfo and my OpenCL application works in RUNLEVEL 3 mode. Both without a need of root privileges.

clinfo:

Number of platforms: 1
  Platform Profile: FULL_PROFILE
  Platform Version: OpenCL 2.0 AMD-APP (1729.3)
  Platform Name: AMD Accelerated Parallel Processing

I have more success. When using fglrx-core I'm able to run Xorg using intel driver (by preparing xorg.conf where intel driver is directly specified). In case of full fglrx lightdm is staring but after login it looks like Xorg crashes and login page is displayed again.

Other issues:

  • When using fglrx-core clinfo can be executed only once. The second time fglrx-core crashes.
  • VT are only available on monitor connected to AMD GPU. I tired to change GPU order in BIOS, but it haven't changed anything.
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natasha
Elite
Elite

Re: X server with integrated GPU

chfast:

In both cases clinfo and my OpenCL application works in RUNLEVEL 3 mode. Both without a need of root privileges.

It's good that it doesn't segfault, but clinfo | grep 'Name:' command gives among others the names of participating devices. To which GPU is the monitor connected?

The idea is to make sure that AMD card does work as OpenCL device without X (in the 3-rd runlevel in order to separate issues connected with run of X on the Intel card), and run X on the Intel card with appropriate xorg.conf. All of this should be done with monitor connected to the Intel card.

The last condition is achieved with tunings of BIOS. Try to do this carefully. Eventually, the BIOS image should be seen when the monitor is connected to the Intel card.

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chfast
Journeyman III
Journeyman III

Re: X server with integrated GPU

I have Tahiti chip, R9 280X.

I don't think I have many options in BIOS to try. I can only select the "primary GPU" of IDGX (probably integrated GPU), PCI1 and PCI2. PCI1 is the default and that's where AMD card is connected. I tried IDGX but VT (linux's virtual terminal) does not shows up on Intel connected monitors.

However, I've figured out how to make Xorg to work with Intel only with fglrx drivers installed. I had to switch to integrated GPU in aticonfig: aticonfig -px-igpu. That pointed GL implementation to Intel one.

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