vgaswitcheroo -- permission denied

[DerekHe]

Hi everyone,

I'm using the guide for vgaswitcheroo that allows user access of graphic switching on a Lenovo T400. I have added this into /etc/rc.local (My username is derek):



chown derek /sys/kernel/debug/vgaswitcheroo/switch


But my access to the "switch" file is still denied like this:


derek@Derek-Laptop:~$ ls -l /sys/kernel/debug/vgaswitcheroo/switch
ls: cannot access /sys/kernel/debug/vgaswitcheroo/switch: Permission denied
derek@Derek-Laptop:~$ sudo ls -l /sys/kernel/debug/vgaswitcheroo/switch
-rw-r--r-- 1 derek root 0 Nov 2 13:36 /sys/kernel/debug/vgaswitcheroo/switch


It's seen here that the file owner is already set. Anyone here with a solution? Thanks a lot.

[lisati]

First of all, be very careful about doing a chown on system files and folders, it can contribute to system breakage!

You might want to use "sudo" in front of the command that requires admin permissions. Have a look here: https://help.ubuntu.com/community/RootSudo

[jocko]

chown derek /sys/kernel/debug/vgaswitcheroo/switch
But:
derek@Derek-Laptop:~$ sudo ls -l /sys/kernel/debug/vgaswitcheroo/switch
-rw-r--r-- 1 derek root 0 Nov 2 13:36 /sys/kernel/debug/vgaswitcheroo/switch

You need to change both user and group permissions, otherwise it will still be inaccessible to you, so this should work:


chown derek:derek /sys/kernel/debug/vgaswitcheroo/switch

[jocko]

First of all, be very careful about doing a chown on system files and folders, it can contribute to system breakage!

You might want to use "sudo" in front of the command that requires admin permissions. Have a look here: https://help.ubuntu.com/community/RootSudo
I agree that it is potentially harmful to to change permissions on system files. It's probably safer to do all the vgaswitcheroo stuff with sudo...

[DerekHe]

Well it's found out that the user doesn't have access to /sys/kernel/debug which is set to 700. Setting it to 755 solves the problem.

[Ji Ruo]

I found the solution to this here (http://askubuntu.com/questions/103253/how-do-i-turn-off-the-radeon-gpu-ono-my-hp-pavilion-dm4) in the answer provided by user42257. I have added the sudo command in front to avoid beginner confusion:


sudo chmod -R 705 /sys/kernel/debug # this isn't noted on the help.ubuntu-page, yet I had to do this since 11.04
sudo chown -R $YOURUSERNAME:$YOURUSERNAME /sys/kernel/debug/vgaswitcheroo # where $YOURUSERNAME is your user name

[_JT]

I found the solution to this here (http://askubuntu.com/questions/103253/how-do-i-turn-off-the-radeon-gpu-ono-my-hp-pavilion-dm4) in the answer provided by user42257. I have added the sudo command in front to avoid beginner confusion:
Is there a way to automate this so I don have to do this every single time I boot? Kind of annoying...