[mythtv-users] Machine lock ups, I need help

Ray Olszewski ray at comarre.com
Fri Dec 5 01:50:39 EST 2003


At 12:08 AM 12/5/2003 -0600, rick bradshaw wrote:
>I know that the documentation says that it can't lock up the system
>cause it is a user process, but it seems to happen anyway. This is
>what I see when I run the mythfrontend and select watch TV. The screen
>goes blank and the lights( caps lock and what not ) on my keyboard
>blink.

That's a kernel OOPs. (OOPs is, in this setting, a technical term, not a 
metaphor. It means, simplified a bit, that the Linux kernel made an error 
it could not recover from. If you had a console open, the kernel would, 
with its last breath of life, try to display a detailed OOPs message on it. 
Another signal it sends, if it can, is to, in your phrase, make "the 
lights( caps lock and what not ) on my keyboard blink".)

It's not quite true that "it" cannot lock up the system. The statement is 
true if "it"= MythTV, which itself is a user process (actually, a set of 
them, but that's no matter).

But the overall video capture process involves the bttv kernel driver, 
sound modules, and, of course, disk access. Something other than MythTV as 
such is causing your problem. And hardware problems (an overheating CPU, or 
bad RAM, or an underpowered power supply) can also manifest themselves as 
kernel OOPses. Finally, the nvidia X driver uses a custom framebuffer that 
is a kernel module.

What might it be? Hard to say, since you end up with no disgnostics. A few, 
not *quite* random questions.

1. What wattage is the power supply rated at?

2. What sound drivers are you using (kernel or ALSA)? I've seen problems 
with the VIA chipsets and the stock kernel sound modules before, problems 
that forced me to switch to ALSA for one system I had (but have since 
upgraded).

3. Do you have a way to monitor the system with "top" (say, by running a 
console through an ssh login)? If so, notice what CPU usage levels and what 
RAM use "top" reports just as the system fails.

4. There have been some scattered reports on this list about problems with 
particular builds of the nvidia driver and particular video cards. You 
might search the list archives to see if any of them refer to your 
particular combination. You might also test whether you can watch mpegs or 
avis using xine or mplayer ... xawtv uses a different method of writing 
video from the one (xVideo) that MythTV uses (I haven't used tvtime so 
don't know how it write video to the screen).

Am I right in thinking you mean the kernel OOPses promptly (within a second 
or so)  when you choose "Watch TV"? If so, the first thing I'd look for is 
a hardware problem,  power supply, disk drive, or possibly CPU. Because 
watching "live" TV involves writing to a buffer on the disk drive, it draws 
more power both to encode and to access the drive, it runs the CPU harder 
(hence hotter), and it accesses the disk drive pretty much constantly. 
These things are all different from tvtime and xawtv.

You might also see whether you get the same problem with --

         recording a TV show
         watching a show you've previously recorded

If it happens with one and not the other, that will help you focus in on 
likely sources of the problem.

In closing, I note you are running a 1 GHz Athlon. That is marginal in CPU 
capability for Myth. I wouldn't expect it to cause a kernel crash, but you 
are probably pushing this hardware fairly hard, particularly if you are 
using default Myth capture resolution (480x480 or the PAL equivalent). So 
you might try reducing resolution to (for example) 320x240, just to see if 
that changes anything.



>mythtv at death:~$ /usr/local/bin/mythbackend --verbose
>Starting up as the master server.
>2003-12-04 23:56:18 Enabled verbose msgs : important general
>2003-12-04 23:56:20 Found changes in the todo list.
>2003-12-04 23:56:48 MainServer::HandleAnnounce Playback
>2003-12-04 23:56:48 adding: death as a player 0
>2003-12-04 23:56:48 MainServer::HandleAnnounce Playback
>2003-12-04 23:56:48 adding: death as a player 1
>2003-12-04 23:56:48 MainServer::HandleAnnounce Playback
>2003-12-04 23:56:48 adding: death as a player 0
>2003-12-04 23:56:48 MainServer::HandleAnnounce Playback
>2003-12-04 23:56:48 adding: death as a player 0
>2003-12-04 23:56:48 adding: death as a remote ringbuffer
>2003-12-04 23:56:49 Changing from None to WatchingLiveTV
>Unknown video codec:
>
>My system is as follows.
>
>athlon 1 Ghz
>512 Mb ram
>ATI wonder VE pci
>Nvidia Geforce MX 440 nvidia driver (4496)
>Via82xxx sound card
>Debian Unstable
>2.4.22 kernel.org kernel
>
>I tried the regular debian packages and same problem, I tried CVS and
>same problem. I can use xawtv and tvtime just fine with this
>setup. Please someone must have some insight into the problems I am
>facing?





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