On 11/2/2013 12:23 AM, Bart Van Assche wrote:
On 31/10/2013 5:24, Sagi Grimberg wrote:
+ * @type3_inc_reftag: T10-DIF type 3 does not state
+ * about the reference tag, it is the user
+ * choice to increment it or not.
Can you explain this further ? Does this mean that the HCA can check
whether the reference tags are increasing when receiving data for TYPE
3 protection mode ? My understanding of SPC-4 is that the application
is free to use the reference tag in any way when using TYPE 3
protection and hence that the HCA must not check whether the reference
tag is increasing for TYPE 3 protection. See e.g.
sd_dif_type3_get_tag() in drivers/scsi/sd_dif.c.
Bart.
As I understand TYPE 3, the reference tag is free for the application to
use - which may choose to inc it each PI or not. This option allows the
application to inc ref_tag in type 3.
The DIF check is determined via check_mask. As I see it, correct use in
case of DIF TYPE 3 is not to validate reference tag i.e. set REF_TAG
bits in check_mask to zero.
Sagi.
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