On Tue, Aug 21, 2007 at 12:04:17AM +0200, Segher Boessenkool wrote: > And no, RMW on MMIO isn't "problematic" at all, either. > > An RMW op is a read op, a modify op, and a write op, all rolled > into one opcode. But three actual operations. Maybe for some CPUs, but not all. ARM for instance can't use the load exclusive and store exclusive instructions to MMIO space. This means placing atomic_t or bitops into MMIO space is a definite no-go on ARM. It breaks. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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