lkml.org 
[lkml]   [2012]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] NVMe: Fix compilation on architecturs without readq/writeq

    * 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


    \
     
     \ /
      Last update: 2012-01-31 13:27    [W:0.025 / U:95.072 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site