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From: Edward Cree <ecree@solarflare.com>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: Shradha Shah <sshah@solarflare.com>, netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next] sfc: Use __iowrite64_copy instead of a slightly different local function
Date: Tue, 29 Jul 2014 16:03:51 +0100	[thread overview]
Message-ID: <53D7B7D7.2030405@solarflare.com> (raw)
In-Reply-To: <1406427279.29010.139.camel@deadeye.wl.decadent.org.uk>

On 27/07/14 03:14, Ben Hutchings wrote:
> __iowrite64_copy() isn't quite the same as efx_memcpy_64(), but
> it looks close enough:
>
> - The length is in units of qwords not bytes
> - It never byte-swaps, but that doesn't make a difference now as PIO
>   is only enabled for x86_64
> - It doesn't include any memory barriers, but that's OK as there is a
>   barrier just before pushing the doorbell
> - mlx4_en uses it for the same purpose
>
> Compile-tested only.
>
> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Edward Cree <ecree@solarflare.com>

On my test system, __iowrite64_copy compiles to use "mov    %rax,(%rdi)"
which we believe is safe (all writes will be naturally-aligned 64-bit
accesses, as required by the hardware).

  reply	other threads:[~2014-07-29 15:04 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-27  2:14 [PATCH net-next] sfc: Use __iowrite64_copy instead of a slightly different local function Ben Hutchings
2014-07-29 15:03 ` Edward Cree [this message]
2014-07-29 22:30 ` David Miller

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