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#1 2005-04-07 10:42:47

shiner_man
Member
From: Atlantic City, NJ
Registered: 2005-04-07
Posts: 29
Website

/dev/nvidiactl permissions

Well, I get that famous error about the permissions being too restrictive on /dev/nvidiactl.  I read a few posts on this forum about people getting the same issue.  I did the following:

groupadd video
gpasswd -a me video

ls -l /dev/nvidiactl
crw-rw----  1 root video 195, 255 1969-12-31 19:00 /dev/nvidiactl

I rebooted and I still get the error.  I'm not sure were to go from here.

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#2 2005-04-07 14:51:47

twpvw5
Member
From: Columbia, MO, US
Registered: 2005-03-06
Posts: 45

Re: /dev/nvidiactl permissions

You might I've got an nVIdia card as well and the permissions on mine are as follows:

crw-rw-rw-  1 root video 195, 255 2005-04-01 17:33 /dev/nvidiactl

if you are using UDEV I bet you also need to add these perms. to your **.rules and/or **.perms files


-The more engineering courses I take, the more I lose my heart for engineering. I just want to F*@%ing build stuff!

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#3 2005-04-07 16:13:36

shiner_man
Member
From: Atlantic City, NJ
Registered: 2005-04-07
Posts: 29
Website

Re: /dev/nvidiactl permissions

hmmm...not sure if I am using udev and not sure exactly what udev does.  You gave me a start though.  I'll check it out when I go home.

P.S.  I have a few more issues and it seems the Arch community is very helpfull so I will be posting them.  You guys and your distro rock.

<EDIT>If I understand the document I just read correctly, hotplug needs udev to work.  I am using hotplug and that is another one of my issues which I'll deal with later.  So I must be using udev.</EDIT>

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#4 2005-04-07 21:43:11

shiner_man
Member
From: Atlantic City, NJ
Registered: 2005-04-07
Posts: 29
Website

Re: /dev/nvidiactl permissions

Okay fyi, I had to change permissions on both /dev/nvidia0 and /dev/nvidiactl:

# chmod 666 /dev/nvidia0
# chmod 666 /dev/nvidiactl

That did the trick.

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#5 2005-04-07 21:48:43

puntmuts
Member
Registered: 2005-02-22
Posts: 138

Re: /dev/nvidiactl permissions

shiner_man wrote:

hmmm...not sure if I am using udev and not sure exactly what udev does.  You gave me a start though.  I'll check it out when I go home.

P.S.  I have a few more issues and it seems the Arch community is very helpfull so I will be posting them.  You guys and your distro rock.

<EDIT>If I understand the document I just read correctly, hotplug needs udev to work.  I am using hotplug and that is another one of my issues which I'll deal with later.  So I must be using udev.</EDIT>

Udev is the successor of devfsd. Udev is software which creates dynamicly devicefiles in /dev.  Udev needs hotplug, but this is a one way dependency (hotplug does not need udev).


Out / Gone
Mirgrating all my machines off ArchLinux . No longer part of the ArchLinux community / users .
Done. Goodbye.

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#6 2005-04-08 12:34:11

shiner_man
Member
From: Atlantic City, NJ
Registered: 2005-04-07
Posts: 29
Website

Re: /dev/nvidiactl permissions

Well, I see devfsd running at boot so I guess I'm not using udev.  Strange thing though, after reboot the permissions are set back on /dev/nvidiactl to 660.  Strange.

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#7 2005-04-08 13:48:11

mico
Member
From: Slovenia
Registered: 2004-02-08
Posts: 247

Re: /dev/nvidiactl permissions

To use udev, add devfs=nomount to the append field in /etc/lilo.conf (or similar for grub). Of course you also need to have udev installed. I think that's all, but search the old news on www.archlinux.org, there was instruction how to do it and also how to change permissions.

Then I'd say you need to add this:

KERNEL="nvidia*", GROUP="video", MODE="0666"

to /etc/udev/rules.d/00.rules

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#8 2005-04-09 03:14:34

neotuli
Lazy Developer
From: London, UK
Registered: 2004-07-06
Posts: 1,204
Website

Re: /dev/nvidiactl permissions

This has been pissing me off for some time now.
If /dev/nvidia* is in group video, and gives rw permission to that group, and I am in that group...then what gripes does it have about insufficient permissions???
*mumble*


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#9 2005-04-09 09:49:53

mico
Member
From: Slovenia
Registered: 2004-02-08
Posts: 247

Re: /dev/nvidiactl permissions

I left the default permissions 660 and am a member of group video. The only thing that doesn't work is the xscreensaver with GL screensavers. This happened after xscreensaver upgrade, http://bugs.archlinux.org/index.php?do=details&id=2503
as someone said there, it has suid and it probably changes to another user, like nobody, who is not in group video.

Sure it works with 666 but that should not be necessary. IMHO this issue still needs better solution than this. I don't know if unsetting the uid bit of xscreensaver would be good, because then it would do everything under my account.

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#10 2005-04-11 23:16:56

shadowhand
Member
From: MN, USA
Registered: 2004-02-19
Posts: 1,142
Website

Re: /dev/nvidiactl permissions

It works for me.

 stat /dev/nvidia*

  File: `/dev/nvidia0'
  Size: 0               Blocks: 0          IO Block: 4096   character special file
Device: bh/11d  Inode: 92693       Links: 1     Device type: c3,0
Access: (0660/crw-rw----)  Uid: (    0/    root)   Gid: (   91/   video)
Access: 2005-04-11 18:14:50.385174720 -0500
Modify: 2005-04-11 18:14:50.385174720 -0500
Change: 2005-04-11 18:14:50.385174720 -0500
  File: `/dev/nvidiactl'
  Size: 0               Blocks: 0          IO Block: 4096   character special file
Device: bh/11d  Inode: 92682       Links: 1     Device type: c3,ff
Access: (0660/crw-rw----)  Uid: (    0/    root)   Gid: (   91/   video)
Access: 2005-04-11 18:14:50.380175480 -0500
Modify: 2005-04-11 18:14:50.380175480 -0500
Change: 2005-04-11 18:14:50.380175480 -0500

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#11 2005-04-12 01:18:33

neotuli
Lazy Developer
From: London, UK
Registered: 2004-07-06
Posts: 1,204
Website

Re: /dev/nvidiactl permissions

I read up on setuid and xscreensaver. It is setuid root becausee of it's screen locking mechanism that needs to read shadow password info, so some very small parts of code need to run as root. After these parts of code have been run, it changes to an unpriviledged user such as nobody, rather than the user that started the process.
According to their website, if PAM is set up correctly on the system in question, the program actually doesn't need to run as root, so it should be OK to take away the setuid bit, and it will run as the user that started it.
Noting that PAM is set up correctly under Arch, I took away the setuid bit and everything seems to work fine, including screen locking. YMMV


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