No vga/vgaswitcheroo in /sys/kernel/debug (Ubuntu 13.10)

Question

I am aware of some of the other threads on this problem, but I have tried the options found in those without success:

sudo su
cat /sys/kernel/debug/vgaswitcheroo/switch

gives

cat: /sys/kernel/debug/vgaswitcheroo/switch: No such file or directory

Could it be because my xorg.conf is only setting up the intel device?

The /sys/kernel/debug appears to be mounted, and I don't have any quirky boot options:

cat /proc/cmdline
BOOT_IMAGE=/boot/vmlinuz-3.11.0-15-generic.efi.signed root=UUID=8a15962e-
ad4d-4eb0-96af-37d167313e92 ro quiet splash vt.handoff=7

For modeset I have:

cat /sys/module/i915/parameters/modeset
-1

Not quite sure if that is a problem or not? But I've also tried booting with the i915.modeset=1 radeon.modeset=1 options, and verified the modeset is indeed 1. I also checked mount | grep /sys/kernel/debug showed

none on /sys/kernel/debug type debugfs (rw)

so this is mounted correctly.

lshw -C display shows:

  *-display               
   description: VGA compatible controller
   product: Haswell-ULT Integrated Graphics Controller
   vendor: Intel Corporation
   physical id: 2
   bus info: pci@0000:00:02.0
   version: 09
   width: 64 bits
   clock: 33MHz
   capabilities: msi pm vga_controller bus_master cap_list rom
   configuration: driver=i915 latency=0
   resources: irq:60 memory:f0000000-f03fffff memory:e0000000-efffffff  ioport:5000(size=64)
  *-display
   description: Display controller
   product: Sun XT [Radeon HD 8670A/8670M/8690M]
   vendor: Advanced Micro Devices, Inc. [AMD/ATI]
   physical id: 0
   bus info: pci@0000:06:00.0
   version: 00
   width: 64 bits
   clock: 33MHz
   capabilities: pm pciexpress msi bus_master cap_list rom
   configuration: driver=radeon latency=0
   resources: irq:65 memory:d0000000-dfffffff memory:f0400000-f043ffff ioport:3000(size=256) memory:f0440000-f045ffff

My kernel seems to be compiled with the proper options:

grep -i switcheroo /boot/config-*
/boot/config-3.11.0-12-generic:CONFIG_VGA_SWITCHEROO=y
/boot/config-3.11.0-15-generic:CONFIG_VGA_SWITCHEROO=y

So why would vgaswitcheroo be missing?

Answer 1

I found this

There are two versions of hybrd graphics: MUXed and MUX-less. MUXed have a 
display MUX to switch the displays between the discrete and integrated cards. 
MUXed systems can be switched using vgaswitcheroo. MUX-less do not have a 
display MUX and the displays are only connected to the integrated card. On 
MUX-less systems, the discrete card is solely for rendering, not display. X 
Server 1.14 is required to support rendering and display from different cards. 
Most new laptops (2011+) are MUX-less.

So I think it's highly likely that my system (being a very recent laptop) is MUX-less (i.e. only the Intel card is actually connected to the display), and although I can "switch" through the AMD Catalyst Control Centre (should I be brave/foolish enough to install fglrx) this really just amounts to: "High performance" -> outsource hard graphics calculations to dGPU then reroute them back through the iGPU for display, "Low performance/good battery" -> do calcs on iGPU, then send directly to display. I also have no ability to switch GPUs in the BIOS, which also suggests MUX-less.

Thus, I probably will never be able to use VGA switcheroo.

One other consideration is that the radeon driver does not officially support my card yet (the 8670M code name Mars XT solar system series, not to be confused with OLAND). Thus when I boot up with open source drivers I get messages like No screens found for the radeon. Given that switcheroo needs radeon and intel both to there, it could be somehow failing because the radeon driver doesn't support my card.

If this is true, it leads to the question of how does one switch between ATI/Intel cards (without fglrx) in a MUX-less system.

Answer 2

---

According to this

---

MUXLESS SYSTEMS

First thing you need to do is turn on your discrete GPU if it's not turned on already:

# echo ON > /sys/kernel/debug/vgaswitcheroo/switch

Verify that this worked by issuing this command again:

# cat /sys/kernel/debug/vgaswitcheroo/switch

Now, we have to know IDs that xrandr assigned to your cards. Do this as the regular user again, not root:

$ xrandr --listproviders
Providers: number : 3
Provider 0: id: 108 cap: 0xb, Source Output, Sink Output, Sink Offload crtcs: 3     outputs: 4 associated providers: 2 name:Intel
Provider 1: id: 69 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 6 outputs: 0 associated providers: 2 name:radeon
Provider 2: id: 69 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 6 outputs: 0 associated providers: 2 name:radeon

In my case 3 cards get listed. Notice that both provides 1 and 2 have the same id. In this case my discrete card has id 69 and my integrated card has id 108.

Last thing we need it to tell X to use your discrete GPU for rendering:

$ xrandr --setprovideroffloadsink 69 108

Where the first number is your discrete card and the second one is your integrated card. To verify this worked:

$ DRI_PRIME=1 glxinfo | grep renderer
OpenGL renderer string: Gallium 0.4 on AMD TURKS

You should get Gallium 0.4 as your renderer. From now on all your 3D apps will be rendered on your ATI card, no need to restart X.

Worked in my lenovo u400 with kubuntu 13.10.