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Message-ID: <52D28ED8.6020102@dev.mellanox.co.il>
Date: Sun, 12 Jan 2014 14:47:20 +0200
From: Sagi Grimberg <sagig@....mellanox.co.il>
To: "Martin K. Petersen" <martin.petersen@...cle.com>
CC: Sagi Grimberg <sagig@...lanox.com>,
"Nicholas A. Bellinger" <nab@...erainc.com>,
target-devel <target-devel@...r.kernel.org>,
linux-scsi <linux-scsi@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Christoph Hellwig <hch@....de>, Hannes Reinecke <hare@...e.de>,
Or Gerlitz <ogerlitz@...lanox.com>,
Nicholas Bellinger <nab@...ux-iscsi.org>,
Oren Duer <oren@...lanox.com>
Subject: Re: [PATCH 07/14] target/sbc: Add P_TYPE + PROT_EN bits to READ_CAPACITY_16
On 1/12/2014 2:33 PM, Martin K. Petersen wrote:
>>>>>> "Sagi" == Sagi Grimberg <sagig@....mellanox.co.il> writes:
>>> I don't know of any non-disk devices that actually implement FORMAT
>>> UNIT. Usually such configuration is done using the array management
>>> interface.
> Sagi> So this takes me to a corner I still don't understand, if a LUN is
> Sagi> pre-formatted as T10-protected, what happens to unwritten blocks
> Sagi> read? I mean, SCSI login executes some reads from sevel LBAs
> Sagi> which will probably fail as blocks are unwritten.
>
> Per SBC, PI must be initialized to 0xffffffffffffffff. Since an app tag
> value of 0xffff is an escape, this will prevent both target and
> initiator from performing PI-verification when that block is read.
OK, so this is an implicit escape (which will become explicit in
DIX1.1?). So I will open that in DIF RDMA verbs.
> If a block is subsequently written and no PI is sent from the host
> (WRPROTECT=0), the target must generate valid PI for each block.
>
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