with DIAGNOSE code 1'20', a virtual aachine user can specify any valid CCW chain to be performed on a tape or disk device. Bo I/O interrupts
are reflected to the virtual aachine; theDIAGBOSE instruction is completed only when all I/O commands in the specified CCW chain are
finished. The register specified as Rx contains the virtual device
address. The Ry register contains the address of theCCW chain.
TheCCWs are processed via DMKCCWTR through DMKGIOEI, providing full
virtualI/O in a synchronous fashion (se1f-aodifying CCWs are not
permitted, however) to any virtual machine specified. Control returns
to the virtualmachine only after completion of the operation or
detection of a fatal error condition. EREP support is provided for tape
andDASD devices only; all other devices will present an error condition
in thePSW to the virtual user. Condition codes and error codes are
returned to the virtualsystem. The condition codes and error codes returned are as follows:
cc=OI/O completed with no errors
cc=1 Error condition. Register 15 contains the following:
R15=1 Device is either not attached or the virtual channel is
dedica ted.
R15=5Virtual device is busy or has an interrupt pending.
cc=2 Exception conditions.
following:
Register 15 contains one of the
R15=2Unit exception bit in device status byte=1
R15=3Wrong length record detected.
cc=3 Error Condition:
R15=13A permanent I/O error occurred or an unsupported device was specified. The two rightmost positions of the
user's Ry register contain the firsttwo sense bytes DIAGNOSE code 1'24' requests CP to provide a virtual aachine with
identifying inforaation and status inforaation about a specified virtual
device. The virtual machinemust specify the virtual device for which
information is requested. CP returns inforaation about the virtual
device and associated real device in the RX, Ry, and Ry+1 registers. CP
also provides a condition code identifying the specific device
information returned to the virtual aachine.When a virtual machine issues DIAGNOSE code 1'24', the Rx register must contain the virtual device address for which information is
requested or the value negative 1 (-1).Specify -1 when the device is a
virtual console whose address is unknown to the virtual aachine.When CP returns control to the virtual machine,
registers contain device information. The Ry
information about the virtual device and theRy+1 about the real device. If -1 was specified and CP
console, the Rx register contains information about
the Ry,Ry+l, and Rx
register contains
register information
located the virtual
the virtual console.
CP obtains device informationfroa three control blocks:
device informationfrom the virtual device block (VDEVBLOK), virtual
and real
1-58IB! V!/370 System Logic and Problem Determination--Voluae 1
are reflected to the virtual aachine; the
finished. The register specified as Rx contains the virtual device
address. The Ry register contains the address of the
The
virtual
permitted, however) to any virtual machine specified. Control returns
to the virtual
detection of a fatal error condition. EREP support is provided for tape
and
in the
returned to the virtual
cc=O
cc=1 Error condition. Register 15 contains the following:
R15=1 Device is either not attached or the virtual channel is
dedica ted.
R15=5
cc=2 Exception conditions.
following:
Register 15 contains one of the
R15=2
R15=3
cc=3 Error Condition:
R15=13
user's Ry register contain the first
identifying inforaation and status inforaation about a specified virtual
device. The virtual machine
information is requested. CP returns inforaation about the virtual
device and associated real device in the RX, Ry, and Ry+1 registers. CP
also provides a condition code identifying the specific device
information returned to the virtual aachine.
requested or the value negative 1 (-1).
virtual console whose address is unknown to the virtual aachine.
registers contain device information. The Ry
information about the virtual device and the
console, the Rx register contains information about
the Ry,
register contains
register information
located the virtual
the virtual console.
CP obtains device information
device information
and real
1-58