id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	field_blocks	field_dependson	field_seealso
634	Do not attempt to flush prefetch buffer on ARM920T	Jakub Jermář	Jiri Svoboda	"ARMv4 optionally supports a prefetch buffer, but ARM920T does not implement it. Yet, the initialization boot code in boot/arch/arm32/src/asm.S:

{{{
        # cp15 isb
        mcr p15, 0, r4, c7, c5, 4
        nop
}}}

and the inst_barrier() macro in kernel/arch/arm32/include/arch/barrier.h:

{{{
#if defined PROCESSOR_ARCH_armv7_a
...
#elif defined PROCESSOR_ARCH_armv6 | defined KERNEL
...
#define inst_barrier()    CP15ISB_write(0)
#else
...
#define inst_barrier()    asm volatile ("""" ::: ""memory"")
#endif
}}}

attempt to flush it.

Note how CP15ISB_write() is used for KERNEL for <ARMv6 (and also how the barriers have possibly wrongly empty bodies in the else branch)."	defect	closed	major	0.7.0	helenos/boot/arm32	mainline	fixed	ARM920T, ARMv4, gta02