Patent ID: 7890668
Filing Date: 2011-02-15
Classification: G06F

Abstract:
1. A computer program product for providing indirect data addressing at an input/output (I/O) subsystem of an I/O processing system, the computer program product comprising: a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: receiving a control word for an I/O operation, the control word including an indirect data address for data associated with the I/O operation, the indirect data address including a starting location of a list of storage addresses that collectively specify the data, wherein two successive list entries are located contiguously when a first of said two successive entries comprises a not-set first flag and are located non-contiguously when the first of said two successive entries comprises a set first flag; gathering the data, wherein gathering comprises accessing entries of the list until a last entry is accessed, wherein accessing includes 1) and 2): 1) responsive to an entry of the list comprising, the not-set first flag and a corresponding first storage address, gathering data from a corresponding storage location; and 2) responsive to an entry of the list comprising, the set first flag and a corresponding second storage address, obtaining a next entry of the list from a second storage location; and transmitting the gathered data to a control unit in the I/O processing system.