Multiple targets, represented by multiple Unit Directories, are
fully allowed by the SBP-2 and 1394 specs. A computer, in
particular, is likely to publish multiple SBP-2 units for
In principle, multiple targets represented by multiple unit
directories would be fully independent, aside from sharing
a node's characteristics such as node ID and GUID. In practice
the level of independence depends on the sophistication of
I haven't kept up with the 1212r work; it may change the
terminology somewhat. But I don't believe it adds any
restrictions or limits to what 1394 and SBP-2 allow. In
particular if you have multiple instance directories, and
each one has a (different) unit directory associated with
it, I believe that would represent multiple targets.
Multiple instance directories, each pointing to the same unit
directory, would be different (if 1212r allows that). The unit
directory would have a single management agent; each node is
limited to at most one login to that agent (by SBP-2); this would
effectively be a single target.
I'm not sure if I'm on the email@example.com mailing list (or if I can
post to it), by the way.
>Recently I have been involved in some discussions about what
>constitutes an SBP-2 Target; these discussions have pointed out
>some areas of the SBP-2 spec that are kind of fuzzy. I'm posting
>this question to get an idea of how this issue is viewed by the
>rest of the industry.
>126.96.36.199 target: A node that receives device service or management
>requests from an initiator....
>This has been interpreted to mean that there is only one SBP-2 target
>4.1 Unit Architecture
>In CSR architecture and Serial Bus terminology, targets implemented
>to this standard are units. A Serial Bus node that implements a
>target has a unit directory in configuration ROM that identifies the
>presence and capabilities of the target.
>This implies that each SBP-2 unit directory is a separate target.
>The case not covered by the SBP-2 specification is the one where
>there are multiple instance directories each containing an SBP-2
>unit directory. Is this one target or multiple targets? I have
>been assuming that this represents multiple targets; are my
>Hewlett Packard Company
>18110 SE 34th Street
>Vancouver, WA 98683
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