The following information is returned to the task by the I/O manager, in the I/O request table: • The condition code for the SIO issued for the I/O operation • The compcsite esw • The SENSE tytes returned by the operation (if any) Using the information in this table, the I/O manager enqueues the
request on the specified subchannel, starts theI/O operation, assembles the return information in the requestor's I/O request table, and posts
the synchronization lock in theI/O request tatle signalling that the I/O operation is comFlete. Interruption Handling Supervisor service routines handle three kinds of interruptions:
external interruptions, sve interruptions, andI/O interruptions.
InRSeS, supervisor routines use the SVC (SUPERVISOR CALL) to suspend
the execution or dispatching of a task when that supervisor routine
received control.On an SVC interruption in RSCS, tMTSve is entered. DMTSVC saves the status of the executing task and passes control to the
callingsUFervisor rcutine in supervisor execution mode. RSCS handles external interruptions fro. tasks by searching fer
asynchronous exitrequQsts supplied by tasks. When a request with a
code matching the external interruption code is found, its asynchronousexit is taken; otherwise, the external interruption is ignored. I/O interruptions are handled by the Rses I/O manager. When an
activeIIO request causes an I/O interruption, the status of tbe I/C request is updated to reflect the new information. Otherwise, a search
is made for an asynchronousexit request for the interrupting device. When one is found, the asynchronous exit is taken. Otherwise, tbe
interruption is ignored.Virtual Storage Management
The supervisor virtual storage service routineIftTSTO bandIes requests
ty tasks fer mainWhen a task requests main storage, DftTSiC reserves page(s) of storage for it. Main storage is freed directly by
task programs.
DMTQRQ manages requests for free
queue.SUFervisor routines call
supervisor status queue elements.
clements of the supervisor statusDftTQRQ to reserve and release 3-10 IBM VM/370: System Logic and Problem Determination--Volume 3
request on the specified subchannel, starts the
the synchronization lock in the
external interruptions, sve interruptions, and
In
the execution or dispatching of a task when that supervisor routine
received control.
calling
asynchronous exit
code matching the external interruption code is found, its asynchronous
active
is made for an asynchronous
interruption is ignored.
The supervisor virtual storage service routine
ty tasks fer main
task programs.
DMTQRQ manages requests for free
queue.
supervisor status queue elements.
clements of the supervisor status