From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Date: Fri, 29 May 2020 23:35:51 +0200 > ../arch/sparc/include/asm/percpu_64.h:7:24: warning: call-clobbered register used for global register variable > register unsigned long __local_per_cpu_offset asm("g5"); The "-ffixed-g5" option on the command line tells gcc that we are using 'g5' as a fixed register, so some part of your build isn't using the: KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare from arch/sparc/Makefile for some reason.