Newer kernel

[DagNygren]

Hi

Just upgraded my system from FC32 to FC37 and this means that the kernel is significantly newer. Previosly 5.11.22 and now the current kernel is: 6.2.15

• Needed to do:
  sed -i -e "s/PDE_DATA/pde_data/" dvbloopback/module/dvblb_proc.c
  to get a clean compile of dvbloopback.ko, which is the only one I need and the module loads fine.
  But when MythTV is trying to use it the system will crash with a "Kernel stack corruption" message.

Worked fine with the old kernel.

Any hints on what may be wrong? And how do I start debugging this?

[Strunzdesign]

Hi,

I can report that kernel 6.2.14 works without such a crash here.

Yes, I had to apply a sed command similar to yours for a long time now, and the "dvbloopback.patch" does no longer apply cleanly, but with some manual tweaking this thing can still be made operational. However, with each kernel bump I fear that it may finally break.

Hope you get it back working!

Regards,
Florian

[DagNygren]

Thanks for confirming that. I wonder if this has something to do with the fact that I use 5 loopback interfaces in parallell. 4 for a DVB-T2 setup and one for a DVB-S2 channel. The crash also seems to come at a taskswitch if I can sort out the crash report right. Some region that should be protected? At the moment I just kicked out the loopback altogether as I don't have an immediate need to use a cardreader.

[Strunzdesign]

Hi,

an excerpt from the ffdecsawrapper config file:

                     # Number of real adapters installed in your system
                     # Count starts at 0 (zero), so if you have 2, choose 1

ADAPTERS="3"

                     # Number of adapters dedicated to ffdecsawrapper
                     # Maximum is 4 because max 8 adapters are permitted in your system.
                     # (4 real + 4 loopback) If you need more, like me, recompile your kernel.
                     # So if you have 2 adapters, you need to set "-j a:c -j b:d" in JOIN=" "

NUMADAPTERS="4"

5 adapters is too much, maybe that is the cause for your kernel crash.

Regards,
Florian

[DagNygren]

Hmm. Interesting. Remember having that problem a long time ago, but in the stuff checked out from GIT there is no such text anywhere and DVBLB_MAX_ADAPTERS is defined to 32 so there should be plenty.

mythserv:ffdecsawrapper <ena> 1027 % grep -r DVBLB_MAX_ADAPTERS .
./dvbloopback/module/dvb_loopback.c:	if (num_adapters < 1 || num_adapters > DVBLB_MAX_ADAPTERS) {
./dvbloopback/module/dvb_loopback.c:		       " 1 and %d\n", num_adapters, DVBLB_MAX_ADAPTERS);
./dvbloopback/module/dvblb_internal.h:#define DVBLB_MAX_ADAPTERS 32
mythserv:ffdecsawrapper <ena> 1028 %

And keep in mind that this has worked fine for many, many years with the same setup. Just recompiled when upgrading kernels.

[Strunzdesign]

Hmm, no idea where I got that config file from. I just tried to find it in order to check and compare it, but failed. Either I'm blind and can't see it in the repositories, or my version of it is old and was removed from the repos in the past. If that is true, then the aforementioned limit may be outdated information. Interesting.

Just my 2 cents. I still hope you can fix it. Kernel 6.3.5 is also working ;-)

[DagNygren]

Thanks for trying anyway. And I did solve my problem by configuring out the dvbloopback ATM...