lkml.org 
[lkml]   [2014]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 09/14] target/configfs: Expose protection device attributes
On 1/12/2014 2:43 PM, Martin K. Petersen wrote:
>>>>>> "Sagi" == Sagi Grimberg <sagig@dev.mellanox.co.il> writes:
>>> The IP checksum is only supported by DIX between OS and initiator,
>>> not by the target. I guess we could signal to the initiator via a
>>> vendor-private VPD that IP checksum is supported directly. But now
>>> what we have hardware-accelerated T10 CRC I don't think it's a big
>>> deal.
> Sagi> shouldn't it stick around if it is not deprecated yet, the
> Sagi> transport is required to support ip-csum->CRC conversion anyhow.
>
> SBC mandates that the guard tag on the wire and on the target device be
> the T10 CRC. The IP checksum is a DIX-optimization for application-HBA
> exchanges. The only place you should support the IP checksum is in the
> initiator.

Right.

> Note that you could conceivably do a T10 CRC to IP checksum conversion
> on writes received by the target and store the IP checksum on disk. And
> then convert back to T10 CRC when the data is eventually read. But it
> makes no sense to do that given that you will have to do the T10 CRC
> calculation regardless. Even if the backing store is DIX-capable and
> supports the IP checksum.
>

I agree, but for backstore DIF (SW) emulation it will make sense.


\
 
 \ /
  Last update: 2014-01-12 14:01    [W:0.086 / U:0.144 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site