[RFC PATCH v2] xfree86: add a -gpu switch to select primary gpu

[Alexander E. Patrakov]

2013/6/21 Maarten Lankhorst <maarten.lankhorst at canonical.com>:
> Op 21-06-13 12:43, Alexander E. Patrakov schreef:
>> 2013/6/21 Maarten Lankhorst <maarten.lankhorst at canonical.com>:
>>> For the open source drivers there should be a different way to do so, try
>>> running this before starting X:
>>>
>>> if [ -f /sys/kernel/debug/vgaswitcheroo/switch]; then
>>>   echo DIS > /sys/kernel/debug/vgaswitcheroo/switch
>>>   echo ON > /sys/kernel/debug/vgaswitcheroo/switch
>>> fi
>> According to https://help.ubuntu.com/community/HybridGraphics:
>>
>> echo DIS > /sys/kernel/debug/vgaswitcheroo/switch
>> Connects discrete graphics with outputs.
>>
>> I assume this is for laptops that can dynamically switch their HDMI or
>> other outputs from one card to another. However, this is completely
>> different from what my Sony laptop provides. The cards and their
>> outputs are physically separate. The Intel card is in the laptop, and
>> can drive the internal panel, the VGA and the HDMI output. The Radeon
>> card is in the dock station, is always on (there is no ATPX method in
>> ACPI tables), works only from AC and has its own VGA and HDMI outputs,
>> also located on the dock station. So this laptop, when docked, can
>> drive five different displays, including the internal one. And I want
>> to connect the TV to the HDMI output in the dock station because it is
>> convenient (less cables attached to the side of the laptop itself).
>>
>> As I am physically away from this laptop, I cannot check whether
>> vgaswitcheroo works (but assume it shouldn't).
> Correct, but it should work on muxless too, switching will power off the intel, which is
> why you have the second line.. It will re-enable the intel, but keep radeon as primary,
> similar to what you are doing with -gpu 1.

The problem is that I have CONFIG_VGA_SWITCHEROO=y in my kernel, but
no /sys/kernel/debug/vgaswitcheroo. Let me rephrase the question:
would you expect this directory to exist in a desktop system with two
GPUs, one onboard and one installed by yourself into a PCIe slot, but
with the BIOS always insisting that the onboard one is the primary
VGA?

--
Alexander E. Patrakov