[mythtv-users] System crashes on start of DVB-S recording

[Bruce Taber]

Jelte Veldstra wrote:
> This issue really drives me mad and I was wondering if others have
> experienced the same.
> 
> I have built a dedicated backend based on CentOS 5 (with DVB support
> from centos.plus kernels) and MythTV 0.21-fixes. It is currently fitted
> with two Hauppauge Nova-S (budget) DVB-S adapters. Encrypted channels
> are decrypted using open-sasc-ng and a subscription card in a phoenix
> smartcard reader.
> 
> This setup works quite well but every now and then (~ 1 in 100
> recordings) I have this setup hardlocking on me as a recording is
> started. After restarting the system and looking into the logfiles there
> is nothing that hints what happened that made it crash. It looks as if
> the power plug was pulled as syslog shows nothing on the Linux level.
> The backend log only shows the line that indicates a recording is
> started and nothing since. The sasc-ng log shows no attempt of the
> backend connecting to it for this recording. The system has had its
> share of stress tests to rule out memory, power or overheating problems
> and has shown no such issues.
> 
> As MythTV and sasc-ng run as non-privileged users it seems like
> something is going on on kernel and driver level. This thought is
> enforced as it only seems to happen with stv0299 based adapters (such as
> the Nova-S). Having used a single Twinhan 1030A DVB-S adapter (dvb-bt8xx
> based) for a while never failed on me. And when I mixed both types (I
> really want a twin-tuner system) it would occasionally crash on the
> Nova-S but never on the Twinhan.
> 
> So somehow it seems related to the hardware, but as I tried three
> different stv0299 based tuners, it's not a faulty adapter is seems but
> rather a driver issue. If I could find a second 1030A then I would try
> that for sure, but I havent been able to find one, plus I'd really like
> to understand what's going on here. Searching linuxtv.org
> <http://linuxtv.org> mail archives doesn't provide answers on that.
> 
> Googling for it revealed some possible hints. One suggestion was that it
> could be multirec in combination with open-sasc-ng. Others have found
> that multirec not being 100% working with open-sasc-ng but had no
> crashes. To rule is out I have disabled multirec, but still have had
> crashes. Another suggestion was that a race condition could arrise
> between software RAID5 code and the DVB subsystem (would explain why
> there are no kernel messages during or after the crash). As I used soft
> RAID5 I have since removed that configuration from my setup, but still
> no luck.
> 
> So I have spent quite some time googling and trying out what I found
> there, but no luck yet. I'm runnning out of ideas and wondered if other
> MythTV users have had similar issues or found a pattern. So far I cannot
> reproduce it and the only pattern so far is that it only happens at the
> start of a recording (never during or outside recordings) and on stv0299
> based adapters.
> 
> If you recognise this or have any pointers for me to try, please share.
> 
> Thanks in advance,
> 
> 
> Jelte
> 
> 
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My system suddenly started this same type of behavior. The problem was
finally traced down to a faulty onboard Ethernet port. Disabling the
Ethernet in the BIOS and installing a separate card eliminated the
problem completely.

Bruce