Created attachment 292021 [details]
kernel .config (kernel 5.9-rc1, PowerMac G5 11,2)

[...]
  CALL    scripts/checksyscalls.sh
  CALL    scripts/atomic/check-atomics.sh
  CHK     include/generated/compile.h
  CC      arch/powerpc/mm/book3s64/hash_utils.o
In file included from ./arch/powerpc/include/asm/processor.h:9,
                 from ./arch/powerpc/include/asm/thread_info.h:40,
                 from ./include/linux/thread_info.h:38,
                 from ./include/asm-generic/preempt.h:5,
                 from ./arch/powerpc/include/generated/asm/preempt.h:1,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from arch/powerpc/mm/book3s64/hash_utils.c:21:
arch/powerpc/mm/book3s64/hash_utils.c: In function ‘hash__early_init_mmu_secondary’:
arch/powerpc/mm/book3s64/hash_utils.c:1119:21: error: ‘default_uamor’ undeclared (first use in this function)
 1119 |   mtspr(SPRN_UAMOR, default_uamor);
      |                     ^~~~~~~~~~~~~
./arch/powerpc/include/asm/reg.h:1396:33: note: in definition of macro ‘mtspr’
 1396 |          : "r" ((unsigned long)(v)) \
      |                                 ^
arch/powerpc/mm/book3s64/hash_utils.c:1119:21: note: each undeclared identifier is reported only once for each function it appears in
 1119 |   mtspr(SPRN_UAMOR, default_uamor);
      |                     ^~~~~~~~~~~~~
./arch/powerpc/include/asm/reg.h:1396:33: note: in definition of macro ‘mtspr’
 1396 |          : "r" ((unsigned long)(v)) \
      |                                 ^
make[3]: *** [scripts/Makefile.build:283: arch/powerpc/mm/book3s64/hash_utils.o] Error 1
make[2]: *** [scripts/Makefile.build:500: arch/powerpc/mm/book3s64] Error 2
make[1]: *** [scripts/Makefile.build:500: arch/powerpc/mm] Error 2
make: *** [Makefile:1789: arch/powerpc] Error 2