Re: [PATCH 07/14] target/sbc: Add P_TYPE + PROT_EN bits to READ_CAPACITY_16

[Sagi Grimberg]

On 1/12/2014 2:33 PM, Martin K. Petersen wrote:
> > > > > > "Sagi" == Sagi Grimberg <sagig@xxxxxxxxxxxxxxxxxx> 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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