I I 19:08:40 q 131 I 19:08:50 DASD 131 ATTACH TO OPERATOR 191 I I 19:08:58 g v 191 I 19:09:04 DASD 191 ON DEV 131 L--- ________________________________________ Signalling attention takes the user back to the virtual machine
level, where an attention interrupt is reflected. The virtual CP system
then responds with the time and issues a read. At the virtual CP system
level, the user issues a QUERY 131, which for the operator is a query of
what appears to him as real disk 131. Note that the status is that of
the disk attached to the operator as virtual address 191. This is the
same disk that was previously noted; however, the virtual CP system
thinks that the disk has read/write status. The single attention again
causes a read, and the user issues a QUERY VIR'IUAL 191. The response
indicates a dedicated disk on device 131 and assumed read/write status.
19:09:16 ipl 190
19:09:23 CMS.,FLOOR •• mm/dd/yy DMSACC112S IA (191) , DEVICE ERROR R; T=0.02/0.04 19:11:29 L-- __________________________________ Signalling attention again causes a CP read, and the operator
performs a virtual IPL of the virtual 190 disk to load the system.
The response is from the CMS system running in a virtual machine under a
virtual VM/370 system running under a real VM/370 system. A carriage
return to the ensuing read gives an error message from CMS. The error
message appears because CMS has an indication from the virtual CP system
that it has write access to the disk (since it appears as a dedicated
disk). However, the real CP system has the disk in read-only status and
rejects the write attempt to the virtual CP system, which in turn
reflects it tc CMS, causing the device error message. I !! I CP I det 333 I DASD 333 DETACHED I link virtest 191 333 w I ENTER WRITE PASSWORD: I I DASD 333 LINKED R/i The user then enters the real CP mode by signalling attention. The
user detaches device 333 and links to it as 333 in write mode. The
fact that the operator detached and relinked is transparent to the
virtual CP system at this level. The user has accomplished a status
cbange from read to write. The physical extent definition has not
changed. Section 2. VM/370 in a Virtual Machine 65

19:15:38 det 1911att 333 operator 191
19:15:52 DASD 131 DETACHED OPERATOR 191
19:15:52 DASD 191 DETACHED
19:15:43 DASD 333 ATTACH TO OPERATOR 191
;9:;5:53 b CMS acc 191 a
R; T=0.39/0.76 19:16:23 L--- Signalling attention causes a read from the virtual CP system, where
the operator detaches the virtual 191 disk and attaches the real 333
disk to his userid as 191. Note that the 333 appears to the virtual CP system as a real disk, when it actually is a virtual disk. The BEGIN
command changes the virtual machine environment to CMS. The ACCESS 191
command is then successfully completed, giving write access to the
virtual 191 disk, which is the virtual CP system's 333 disk previously
linked in write mode. r--- I print profile exec I 19:16:45 PRT DOE OUTPUT OF OPERATOR FILE = 0002 LINES= 00013 , R; T=0.23/0.51 19:16:46 I I I 19:17:05 drain OOe I 19:17:04 PRT OOE SPOOL CLS XA DRAINED L--- ______________________________________________________________ From CMS, the PROFILE EXEC is printed. The virtual CP system
respcnds with a printer output message for file 2, which is the output from the previous print function. The ready message is the response
from the CMS system. This example shows a virtual machine running with
a virtual ccnsole that is receiving both virtual machine and CP messages. Signaling attention places the virtual machine in virtual CP mode, where the user can specify a drain of device OOE. The system
responds with a message indicating that the device is drained. This
indicates that the virtual CP system has completed printing on what it
thinks is a real printer. This printer is actually spooled by the real CP system. r--- I ! ! I CP I close OOe I b I CMS L
Signalling attention returns the user to the real CP system level,
where he issues a CLOSE OOE command, followed by a BEGIN. This allows
him to have the spooled output of the virtual VMj370 system printed on
the real VM/370 system printer. r---- ---, I ! I I 19:19:44 set dump auto CP I , I I 19:19:51 q dump I I 19:19:55 DASD 330 DUMP UNIT CP 1
66 IBM iM/370 Operating Systems in a Virtual Machine