Re: [PATCH] NVMe: Fix compilation on architecturs withoutreadq/writeq

[Ingo Molnar]

* Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:

> >   u64 val;
> >   val = readl(addr);
> >   val |= readl(addr+4) << 32;
> > 
> > is well-defined and must read the low word first - both at the C level
> > *and* at the CPU level. Anything else would be a bug in the
> > architecture "readl()" implementation or the hardware.
> 
> That doesn't make the access atomic to hardware however as a true 64bit
> readq/writeq would be ?
> 
> It seems to me the two are not quite the same semantically

Correct, and that's what the:

	#include <asm/io-inatomic.h>

line in the driver would express.

Thanks,

	Ingo
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