sched_clock(), used by printk(), calls __USE_RTC() to know whether to use realtime clock or timebase.
__USE_RTC() uses cpu_has_feature() which is initialised by machine_init(). Before machine_init(), __USE_RTC() returns true, leading to a program check exception on CPUs not having realtime clock. In order to be able to use printk() earlier, use feature fixup. Feature fixups are applies in early_init(), enabling the use of printk() earlier. Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr> --- arch/powerpc/include/asm/time.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h index 54f4ec1f9fab..3455cb54c333 100644 --- a/arch/powerpc/include/asm/time.h +++ b/arch/powerpc/include/asm/time.h @@ -42,7 +42,14 @@ struct div_result { /* Accessor functions for the timebase (RTC on 601) registers. */ /* If one day CONFIG_POWER is added just define __USE_RTC as 1 */ #ifdef CONFIG_PPC_BOOK3S_32 -#define __USE_RTC() (cpu_has_feature(CPU_FTR_USE_RTC)) +static inline bool __USE_RTC(void) +{ + asm_volatile_goto(ASM_FTR_IFCLR("nop;", "b %1;", %0) :: + "i" (CPU_FTR_USE_RTC) :: l_use_rtc); + return false; +l_use_rtc: + return true; +} #else #define __USE_RTC() 0 #endif -- 2.13.3