Ubuntu – I can not find /sys/kernel/debug/vgaswitcheroo/switch


I have enable switcheroo in kernel config .
Why is there not /sys/kernel/debug/vgaswitcheroo/switch ?

Linux ubuntu-raid-w500 2.6.38-10-generic #46-Ubuntu SMP Tue Jun 28 15:07:17 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

My computer is Thinkpad W500 . One graphic card is ATI Mobility FireGL V5700 (512 MB). The other one is Intel Graphics Media Accelerator 4500MHD .

I am using official kernel 2.6.38-10, I do NOT customize it. I add kernel option pcie_aspm=force in GRUB_CMDLINE_LINUX_DEFAULT of /etc/default/grub

Best Answer

In Ubuntu 10.10 and up, vgaswitchheroo is already enabled so you don't need extra settings. And /sys/kernel/debug is already mounted, however you need root permissions to read the contents of /sys/kernel/debug, so using sudo su should work.

If there's still no switch, run lspci | grep VGA and make sure both cards are outputted. If one is missing a BIOS setting might be the cause, so check that.

Console example:

sergio@Sergio-L:~$ ls /sys/kernel/debug/vgaswitcheroo
ls: impossível aceder a /sys/kernel/debug/vgaswitcheroo: Permissão negada
sergio@Sergio-L:~$ sudo su
[sudo] password for sergio: 
root@Sergio-L:/home/sergio# ls /sys/kernel/debug/vgaswitcheroo/
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