[haiku-commits] Re: haiku: hrev46864 - headers/private/kernel/arch/arm src/system/kernel/arch/arm src/system/kernel/arch/arm/paging/32bit src/system/kernel/arch/arm/paging
- From: Pawel Dziepak <pdziepak@xxxxxxxxxxx>
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Fri, 14 Feb 2014 05:38:12 +0100
2014-02-13 6:33 GMT+01:00 <kallisti5@xxxxxxxxxxx>:
> static inline void
> memory_write_barrier_inline(void)
> {
> - // TODO Only ArmV7+?
> - asm volatile("dsb sy" : : : "memory");
> + __sync_synchronize();
> }
This can be relaxed for ARMv7 as it provides a proper write barrier (dmb st).
For ARMv5 (and earlier) __sync_synchronize() causes GCC to emit a call
to a helper functions which we don't have (and don't need) in the
kernel. On uniprocessor architectures memory_{full, read,
write}_barrier_inline() do not have to be anything more than just a
simple compiler barrier. #ifdef would be helpful.
Paweł
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