Re: Coding problem with sysfs

[Greg KH <greg@kroah.com>]

On Sat, Jun 05, 2004 at 02:30:33AM +0200, Christian Gmeiner wrote:
> Hi Greg,
> 
> > On Wed, Jun 02, 2004 at 11:21:53AM +0200, Christian Gmeiner wrote:
> > > /sys/class/dvb/adapter0:
> > > demux0  dvr0  frontend  frontend0  name  net0
> >
> > The 'dev' file needs to be here.  That's the problem.
> Oh i forgot something - my fault:
> 
> vdr root # ls -Rl /sys/class/dvb
> /sys/class/dvb:
> total 0
> drwxr-xr-x  5 root root 0 Jun  5 02:22 adapter0
> 
> /sys/class/dvb/adapter0:
> total 0
> drwxr-xr-x  2 root root    0 Jun  5 02:22 demux0
> drwxr-xr-x  2 root root    0 Jun  5 02:22 dvr0
> -r--r--r--  1 root root 4096 Jun  5 02:22 frontend
> -r--r--r--  1 root root 4096 Jun  5 02:22 name
> drwxr-xr-x  2 root root    0 Jun  5 02:22 net0
> 
> /sys/class/dvb/adapter0/demux0:
> total 0
> -r--r--r--  1 root root 4096 Jun  5 02:22 adap
> -r--r--r--  1 root root 4096 Jun  5 02:22 dev
> 
> /sys/class/dvb/adapter0/dvr0:
> total 0
> -r--r--r--  1 root root 4096 Jun  5 02:22 adap
> -r--r--r--  1 root root 4096 Jun  5 02:22 dev
> 
> /sys/class/dvb/adapter0/net0:
> total 0
> -r--r--r--  1 root root 4096 Jun  5 02:22 adap
> -r--r--r--  1 root root 4096 Jun  5 02:22 dev
> 

Hm, how about using 'tree' instead, it's much easier to show the
heirchey with it :)

Anyway, how are you putting struct class_device structures into such a
tree?  We don't currently allow parents of them in the kernel.  Are you
using basic kobjects here?

What hotplug events get generated when you create your "demux0" and
others devices?

The solution is for you to put everything under the /sys/class/dvb/
directory, and not go one level deeper.

Care to post your code?

> > What happens if you run
> > udevtest /sys/class/dvb/adapter0
> 
> vdr root # udevtest /sys/class/dvb/adapter0
> version 025
> looking at '/class/dvb/adapter0'
> configured rule in '/etc/udev/rules.d//10-myrule.rules' at line 2 applied,
> 'adapter0' becomes 'dvb/adapter%n/%k'
> creating device node '/dev/dvb/adapter0/adapter0', major = '250', minor > '7', mode = '020660', uid = '0', gid = '27'

Ok, so that works :)

> >
> 
> This is my udev rule:
> # dvb devices
> SYSFS{adap}="adapter[0-9]*", NAME="dvb/adapter%n/%k"
> 
> And this is the result in /dev:
> 
> vdr root # ls -Rl /dev/dvb
> /dev/dvb:
> total 0
> drwxr-xr-x  2 root root 0 Jun  5 02:22 adapter0
> 
> /dev/dvb/adapter0:
> total 0
> crw-rw----  1 root video 250, 7 Jun  5 02:22 adapter0
> crw-rw----  1 root video 250, 4 Jun  5 02:22 demux0
> crw-rw----  1 root video 250, 5 Jun  5 02:22 dvr0
> crw-rw----  1 root video 250, 7 Jun  5 02:22 net0
> 
> 
> And here is the problem:
> vdr root # ls /dev/dvb/adapter0/demux0
> /dev/dvb/adapter0/demux0
> vdr root # cat /dev/dvb/adapter0/demux0
> cat: /dev/dvb/adapter0/demux0: No such device or address

Ok, that's your kernel driver problem, not a udev issue :)

Are you sure 250:4 is the proper major:minor assigned to your kernel
object?

Again, code would help here.

Good luck,

greg k-h


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