[mythtv-users] Can't open 3rd DVB device - malloc error?

Henry A Harper III hah at alumni.rice.edu
Thu Sep 14 11:06:39 EDT 2006

> -----Original Message-----
> From: Janne Grunau [mailto:janne-mythtvusers at grunau.be]

> On Tuesday 12 September 2006 17:34, Henry A Harper III wrote:
> >
> > I have a fairly new and fancy (for me, anyway) FC5 box built just for
> > mythtv with three ATSC tuners (3 pchdtv hd5500s). I started out with
> > Jarod's howto, mythtv 0.19 and am now at 0.20 svn 11166, new FC
> > drivers from pchdtv.com, kernel 2.6.17-1.2174_FC5smp (A64 x2 4600).
> One information is missing: the amount of memory. Your cards should
> supported by plain Fedora with that kernel version. Please try again
> without the pchdtv.com driver.

I am hoping memory isn't an issue since I have 2x512MB DDR2-800 installed. I
uninstalelled the pchdtv.com v4l drivers by "modprobe -r "-ing the ko's I
found with matching datestamps to the ones I compiled from pchdtv.com, but I
have also disabled my sound in this way so it's probably not the recommended
method. Full dmesg attached.

> > What I can do: switch among all 3 cards (DVB mode only, I'm not using
> > analog) in LiveTV as well as xine, and scheduled two recordings
> > simultaneously (that work). What I can't do: schedule three
> > simultaneous recordings on HD programs and have all three work - I am
> > now up to two at a time working quite well. I have seen three
> > simultaneous recordings on one occasion but one of them was a channel
> > that is broadcasting SD/480i.
> The memory used by the kernel doesn't depend on HD or SD and I can make
> 4 simultaneous recordings with 4 DVB cards. So it isn't a general
> limitation.


> > 2006-09-12 08:16:36.260 DVBChan(1) Warning: Symbol Rate setting (0)
> > is out of range (min/max:5056941/10762000)
> > 2006-09-12 08:16:36.298 Started recording: Good Morning America:
> > channel 1061 on cardid 2, sourceid 1
> ...
> > 2006-09-12 08:16:58.893 DVBChan(2) Warning: Symbol Rate setting (0)
> > is out of range (min/max:5056941/10762000)
> > 2006-09-12 08:16:58.920 Started recording: Today: channel 1071 on
> > cardid 3, sourceid 1
> You might want to fix the symbol rate of these two channels.

Mmm...but since one of the two recordings with that error message did work I
can ignore this for now? Since I don't see an obvious way to do this...is it
in the database somewhere?

> > 2006-09-12 08:16:59.706 DVBRec(2) Error: Failed to open DVB device
> >                         eno: Cannot allocate memory (12)
> But it should be unrelated to this error. Are you sure that your system
> has no memory shortage? The output of free with two HD recordings just
> before and after the start of a third recording would be interesting.

2 recordings:
[mythtv at myth1 ~]$ free -m
             total       used       free     shared    buffers     cached
Mem:          1010        866        144          0         16        479
-/+ buffers/cache:        371        639
Swap:         1983          0       1983

Then I get (with pchdtv drivers removed perhaps incorrectly) the message
which causes mythbackend to become zombified upon starting the 3rd
recording, and there still looks like lots of memory available:

[mythtv at myth1 ~]$ free -m
             total       used       free     shared    buffers     cached
Mem:          1010        995         14          0          0        466
-/+ buffers/cache:        529        481
Swap:         1983          0       1983

Kernel bug message is at the end of dmesg file.

> > Is there a kernel parameter I can tweak to get a
> > bigger memory allocation?
> I don't know but normally if enough memory is available it should just
> work.

I would really like it to "just work" :) Perhaps there is a clue in the
kernel bug message which says "use vmalloc=<size> to increase size"? I am
assuming that's a kernel load time parameter, and I just need to find out
what it's defaulting to and increase by a judicious amount then stick it in

Thanks for your time Janne!

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