[mythtv-users] Odd PVR-350 FC2 Error: /dev/video0 Input/output Error

Jarod Wilson jcw at wilsonet.com
Sat Sep 18 20:33:10 EDT 2004

On Saturday 18 September 2004 08:15, Daniel Savard wrote:
> Well, since I am using a Gentoo distro, the initscripts are not the
> same. So, what my question aimed at is, which user is actually running
> or trying to run the backend? Is there any switch user into the init
> script? May be, if you feel comfortable enough with scripting you can
> look at it. Just to make sure the user is right.
> On Sat, 18 Sep 2004 08:22:27 -0400, vasudeva <vasudeva at megarad.com> wrote:
> > * on 09-17-04, Daniel Savard wrote:
> > > Skipping back to some of my suggestions. The modifications in the
> > > modules.conf never aimed at solving your problem with the access to
> > > the /dev/video0. But, it's a required change to avoid some problems
> > > that may appear later with a mis-behavior of the ivtv driver. So, keep
> > > your modules.conf as suggested if you still use ivtv 0.1.10, if it
> > > happen you go back to ivtv 0.1.9, you old config will be required.
> > >
> > > I guess you have a script in /etc/init.d to startup the mythbackend.
> > > Can you look if the MYTH_USER is appropriately defined there? Just to
> > > make sure it isn't trying to start the backend with a user with
> > > unsufficient privileges. In fact, it should be root. Here, the scripts
> > > may vary from what I have on my system, since I am running a Gentoo
> > > distro.
> >
> > MYTH_USER is not being defined in /etc/init.d/mythbackend.  I did a
> > case-insensitive recursive grep on /etc and MYTH and USER appear
> > nowhere on the same line.  A ps shows mythbackend running as root.
> >
> > I don't know if this is going to be of any use to anyone, but I ran
> > strace on both the device-borking mythbackend, and the dd that fails
> > afterward.  They're too big for me to post to the list, so you can
> > find them here:
> >
> > http://vasudeva.megarad.com/mythbackend.strace.txt
> > http://vasudeva.megarad.com/dd.strace.txt

On Red Hat systems, the backend always runs as root, so there's no need to 
define anything anywhere. Red Hat systems start out with all devices owned by 
root, and chowns them for the logged in user in accordance 
with /etc/security/console.perms. When using an initscript, the backend 
starts before a user has logged in, thus only root has permissions on it, so 
you have to run the backend as root. Unless you hack console.perms, of 
course... In short, permissions on the device shouldn't be an issue in this 
case if vasudeva never edited the initscripts provided by ATrpms.

Jarod C. Wilson, RHCE
jcw at wilsonet.com

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