Kernel modules and Pi board versions

Question

I have a Raspbian image (4.9.59-v7) into which I am loading a kernel module that I have built myself since it is not in the default image (for an ICS43432 MEMS I2S microphone).

I have this working without issue on a Raspberry Pi B+; my module snd_soc_ics43432 is listed as present after boot by lsmod and I know it runs correctly 'cos I can record stuff. I've also modified the boot and rootfs partitions on this SD card to run read-only in preparation for using it in an environment where I have little control over the power supply. Hence the disk image is a fixed thing.

I have now plugged the same SD card into a Pi Zero W and it works there EXCEPT that it is unable to load the ICS43432 module. During boot it says:

systemd-modules-load[92]: Failed to find module 'snd-soc-ics43432'

...and if I use insmod to manually insert the module I get:

ERROR: could not insert module sound/soc/codecs/snd-soc-ics43432.ko: Invalid module format

Running sudo modinfo on this module file returns:

vermagic: 4.9.59-v7+ SMP mod_unload modversions ARMv7 p2v8

...which looks correct to me, and indeed it has to be since the goldarned SD card is read-only.

So what gives? Is there a difference between the Broadcom chips on the Pi Zero W versus the Pi B+ that would cause this? Or is it some sort of timing race condition? Any help/advice is appreciated.

Answer 1

Ah, I think I've answered my own question. My Pi B+ is ARM V7:

processor       : 0
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 57.60
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
vCPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

processor       : 1
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 57.60
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

processor       : 2
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 57.60
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

processor       : 3
model name      : ARMv7 Processor rev 5 (v7l)
BogoMIPS        : 57.60
Features        : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xc07
CPU revision    : 5

Hardware        : BCM2835
Revision        : a01041
Serial          : 00000000a8477217

...while my Pi Zero W is ARM V6:

processor       : 0
model name      : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS        : 997.08
Features        : half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x0
CPU part        : 0xb76
CPU revision    : 7

Hardware        : BCM2835
Revision        : 9000c1
Serial          : 00000000e39dea37

I guess I will have to recompile that kernel module in order to swap between boards.