Re: Compass udrc kernel panic

Annaliese McDermond

On Dec 6, 2018, at 9:48 AM, Basil Gunn <@basil860> wrote:

Anna might comment on the messages coming out of soc:sound. Eventually
the tlv320aic code registers with i2s

snd-udrc soc:sound: tlv320aic32x4-hifi <-> 3f203000.i2s mapping ok
Indeed the mapping fails a few times before it succeeds. This is because of driver dependency ordering. Many times the tlv320aic32x4 driver doesn’t look quickly enough for the other pieces of the sound driver. This is why the framework retries, because module dependencies aren’t always the greatest in Linux.

Bernard Pidoux <bernard.f6bvp@...> writes:

Hi Annaliese,

I recently experienced kernel panics with compass Linux distro with
kernel 4.14.79-v7+ as soon as opening a Chromium window. Kernel panic
does not occur if I rmmod all snd and udrc modules before activating
Chromium. After removing all sound and udrc module, modprobe udrc
does not reload all needed modules for aplay - l to find udrc card. I
attach one of the photo I took from screen while kernel panic. It
shows a null pointer related to bcm2835.
There’s no relation really to BCM2835. The BCM2835 is the Broadcom System on a Chip part number of the SoC on the Raspberry Pi. The Oops message is telling you that it’s running on a Raspberry Pi. It has no real relation to the cause of the panic.

When investigating kernel
panic I noticed a few dmesg messages:
sdhost-bcm2835 3f202000.mmc could not get clk, deferring probe.
This is the Raspberry Pi’s MMC interface on the MMC. It’s just commenting that whatever clock it’s running isn’t ready yet, and it’ll load the driver later. This is a normal condition on the Pi during boot.

udrc: loading out-of-tree module taints kernel.
This just means that we compiled the udrc kernel module “out of tree” instead of “in tree.” That means we don’t have the full Linux kernel source, just the necessary headers. It’s not a part of the kernel itself. This is a normal condition.

snd-udrc soc:sound: ASoC: CODEC DAI tlv320aic32x4-hifi not registered -will retry
snd-udrc soc:sound: snd_soc_register_card() failed: -517
See above.

If you need I can send you more details and screen
I think Basil has a sound analysis here that you’re seeing a panic in the ax25 stack somewhere. I’d have to investigate what the changes to the ax25 stack were between kernel versions and try to bisect it.

If you’d like to know my offhand guess as to what’s happening, I’d guess that Chromium is trying to do a broadcast to all interfaces for some reason. Once you load the ax25 stack, the packet modem becomes a network interface. This broadcast packet is probably triggering a bug in the ax25 stack due to it having some sort of freaky address (or more accurately no address) by the time it gets there. But this is just a wild guess from hearing the symptoms.

Other than the fact it’s saying that the tlv320aic32x4 driver is loaded at the time of panic, there’s nothing here that really points to the udrc; just to the ax25 stack. You might want to poke at the kernel ax25 folks and they may be able to illuminate more. Or Basil grubs around in that chunk of the kernel more than I and may have some knowledge to illuminate the situation.


Dr Bernard Pidoux

Annaliese McDermond (NH6Z)
Xenotropic Systems

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