Messages in this thread | | | Date | Tue, 31 Jan 2012 13:23:39 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] NVMe: Fix compilation on architecturs without readq/writeq |
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* Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Tue, 31 Jan 2012 13:09:22 +0100 > Ingo Molnar <mingo@elte.hu> wrote: > > > > > * Alan Cox <alan@lxorguk.ukuu.org.uk> 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. > > Why would "inatomic" indicate that - I'm confused. It would > imply to me they were extra specially atomic ?
Yeah, s/inatomic/non-atomic.
inatomic would be doubly confusing for the reason that it's already used as an 'in atomic section' sense in the kernel.
> (atomos if from the Greek so in- as a prefix isn't the same > in- as in many other words, welcome to English hell - who > needs perl) > > non-atomic.h might be better, or 'un-atomic' or 'multi-read' > or something ?
non-atomic sounds good to me too.
Thanks,
Ingo
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