Definition of Mandatory

Jim McGrath jmcgrath at qntm.com
Tue Sep 6 09:41:52 PDT 1994


        Reply to:   RE>>Definition of Mandatory

Gene wrote:

> In my comments my fingers came very close to saying that. Then I thought,
the
> task set management rules are really only defined in SAM. At least I hope
they
> are not defined two places - I try to deny the existence of annexes.
 
I agree that the whole task set/queuing sections are unique to SAM.  My
problem is that, as they are currently written, they only provide an
architecture for the management of queuing.  Specifically, they leave the
location (host, target) of the management of the various elements of the task
set largely undefined.  That is, it is perfectly SAM compliance to, say,
implement ordered tasks by having a device driver withhold the issuing of
ordered commands until the device is idle (no queue entries), and then send
them one at a time.  In this case, the target need never see an ordered tag. 
Indeed, I am counting on this interpretation to help make my proposal on ATA
command queuing more "SAM compliant", even though it will only require simple
tags.

Given this, I cannot approve SAM if the interpretation is that it applies to
devices, for in the interests of defining a general architecture (a good and
proper thing to do), it fails to give enough direction to design a compliant
implementation at a target level.


Jim






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