[mythtv-users] [addressed, can't really call it solved] dtv, ivtv swapping /dev/video0, 1 across reboots

Harry Coin hcoin at quietfountain.com
Fri Jun 25 17:36:54 UTC 2010


Thanks one and all for the help sorting this out.  The most do-able bit 
of advice was the simple add to modprobe.d to pass the video device 
number to each driver.

In /etc/modprobe.d/options add these lines:

options ivtv ivtv_first_minor=0
options bttv video_nr=1

The most 'linux-ly correct' way to do it, udev mashery,  must more 
correctly be called 'programming' and not 'option setting'.  How many 
even ambitious users have what it takes to begin with explorations with 
magic like:

udevadm info -a -p $(udevadm info -q path -n /dev/dvb/adapter0/frontend0)

and again for the ivtv card,
and so on and so forth ending with involving comprehending the content 
of udev files with 'obvious' names like '55-custom.rules' and etc.

Plainly this points up a design flaw in the linux kernel.  Notice that 
M$ and others do not require the intervention of high-competence users 
in order for whatever is in a machine to get the same name every time 
the OS boots (unless the hardware is physically changed).    Udev rule 
wizard user intervention should only be required if the user doesn't 
like the default name assignments.   Seriously, look at the complexity 
of that udev command and the subsequent udev rule-- and that only helps 
you get to the answer in several further steps.

Really, at the very least, to improve the appearance of linux usability 
and stability overall,  no user or system integrator activity should be 
required in order for device name assignments to be stable across 
reboots starting from the first reboot after the last hardware change. 
No program should 'break' or 'stop' once working after the first reboot 
following a hardware change.  Imagine the customer or user trying to 
make it 'just work'.  Who wants to get the support call:  "Well when I 
reboot it sometimes it works, and sometimes it just won't.  So I just 
keep rebooting until it works, and then I just leave it on all day and 
all night even when I don't need it because I'm afraid of it not working 
next time I reboot."    To learn the issue isn't a hardware flaw but 
random device name swapping based on bootup timing race conditions? 
That's closer to 'workbench toolset' than 'everyday workhorse'.

I hope the above is received as the constructive observation I intended.

Again thanks to all for the tips!


















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