Chapter 32. The GSI

The Previous Chapter

The previous chapter provided a detailed description of how the SM discovers devices during startup, as well as how it issues attribute accesses to devices that have not yet been assigned LID addresses. It covered:

• Who performs discovery?

• How packets are normally routed (when all devices have already been assigned LIDs).

• Packet routing during discovery (before LIDs have been assigned).

• Accessing device attributes when the path to the device is only partially configured.

This Chapter

This chapter provides a detailed description of the General Services Interface (GSI, aka QP1). It is provided at this point in the book because the SA is accessed via the GSI and the next chapter covers the SA. Specifically, this chapter covers:

• The GSMs, GSAs, and GSIs.

• How to prepare an HCA GSI for use.

• The required versus optional GSAs.

• The SA and the GSI.

• GMPs use a VL buffer determined by the GMP's SL value.

• GMPs can transit routers.

• QP1 is a controlled-access QP.

• QP1's P_Key insertion and checking.

• Additional reference material.

The Next Chapter

The next chapter provides a detailed description of the Subnet Administrator (SA). Specifically, it covers:

• The purpose of the SA.

• The SA is accessed using GMPs.

• The location of the SA.

• Requester access authorization.

• The SA's methods and attributes.

• The definition of a Record Identifier (RID).

• SubnAdmGet() operation.

• SubnAdmSet() operation.

• The definition of a table.

• SubnAdmConfig() operation.

• Database queries using SubnAdmGetTable().

• Fetching the entire database.

• The reliable multi-packet transaction protocol.

• Additional reference information.