Unable to build 0.8.5 for Linux 5.9.x on ppc64le

[zdykstra]

System information

Type	Version/Name
Distribution Name	Void Linux PPC
Distribution Version	Rolling Release, latest
Linux Kernel	5.9.3
Architecture	ppc64le
ZFS Version	0.8.5-1, 2.0.0-rc5
SPL Version	0.8.5-1, 2.0.0-rc5

Describe the problem you're observing

I'm unable to build ZFS 0.8.5-1 or 2.0.0-rc5 for Linux 5.9.3 on ppc64le.

Describe how to reproduce the problem

Build ZFS 0.8.5 or 2.0.0-rc5 for Linux 5.9.3+ on ppc64le.

Include any warning/errors/backtraces from the system logs

  LD [M]  /var/lib/dkms/zfs/0.8.5/build/module/zfs/zfs.o
  MODPOST /var/lib/dkms/zfs/0.8.5/build/module/Module.symvers
FATAL: modpost: GPL-incompatible module zfs.ko uses GPL-only symbol 'shared_processor'
make[2]: *** [scripts/Makefile.modpost:111: /var/lib/dkms/zfs/0.8.5/build/module/Module.symvers] Error 1
make[1]: *** [Makefile:1697: modules] Error 2
make[1]: Leaving directory '/usr/src/kernel-headers-5.9.3_1'
make: *** [Makefile:30: modules] Error 2
make: Leaving directory '/var/lib/dkms/zfs/0.8.5/build/module'

0.8.5

5.9.3.config.log
5.9.3.make.log

2.0.0-rc5

2.0.0-rc5-make.log
2.0.0-rc5-config.log

Notes

module/zstd/zzstd.mod.c: { 0xb2dc434c, "shared_processor" },

zzstd.mod.c.txt

[q66]

this can be worked around by disabling CONFIG_PPC_QUEUED_SPINLOCKS; the culprit here is specifically CONFIG_PARAVIRT_SPINLOCKS, which is enabled with the former and results in inline access to the relevant GPL-only symbol in the headers (arch/powerpc/include/asm/qspinlock.h)

this is not a solution, but i've disabled queued spinlocks on ppc64le in Void's 5.9 kernel for the time being

[zzywysm]

This is reportedly fixed in Linux 5.10.56: https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10.56