MISSING: Fibre-Channel Extensions (FCX) Facility

[Fish-Git]

Fibre-Channel Extensions (FCX) Facility   (February, 2009)

The fibre-channel-extensions (FCX) facility may be available on models implementing z/Architecture. The facility includes enhancements and performance extensions that provide the program a means to transport lists of commands to an I/O device for processing without the channel overhead of fetching and decoding each command.

Use of the FCX facility may be restricted to devices accessible by certain channel path types.

The FCX facility includes the following:

• Changes to the operation-request block (ORB), interruption-response block (IRB), and subchannel-information block (SCHIB).

• A form of a channel program that consists of a transport-control word (TCW) that designates a transport-command-control block (TCCB) and transport-status block (TSB). The TCCB includes a transport-command area (TCA) which contains a list of up to 30 I/O commands that are in the form of device-command words (DCWs). The TSB contains completion status and other information related to the TCW channel program that is complementary to the completion information contained in the IRB.
  
  A TCW may specify the transfer of either input data or output data.

• The ability to directly or indirectly designate any or all of the TCCB, the input data storage area, and the output data storage area. When a storage area is designated directly, the TCW specifies the location of a single, contiguous block of storage. When a storage area is designated indirectly, the TCW designates the location of a list of one or more transport-indirect-data-address words (TIDAWs). TIDAW lists and the storage area designated by each TIDAW in a list are restricted from crossing 4 K-byte boundaries.

• An interrogate operation which may be initiated by CANCEL SUBCHANNEL to determine the state of an I/O operation.

[Fish-Git]

Moved to combined issue #77 "MISSING Facilities support".