In this example: The exclamation mark (!) indicates that an attention
has been signaled. VM/370 reflects this signal as an attention to the
virtual machine. The virtual CP system responds to the attention by
typing the time and issuing a read. The response to the read is the
entry of the QUERY DASD command. The response to this command from the
virtual CP system is the DASD status shown. Notice that most of the
devices are in an offline condition, since at the time of the IFL these
device addresses were not available in the virtual machine
configuraticn. The devices that were available are now marked free,
owned, or system. (The system volumes are ones that have minidisks in
use by the operator.) Notice that device 332 has a label of SYS196 in
the virtual CP system. A previous QUERY VIRTUAL showed that DASD 332 is
actually mounted on PIDSK7. However_ this label is the real system label and is not the one recognized by the virtual CP system.
Fer users tc access the 332 disk, the virtual directory must refer to
the virtual label of syS196. (The operator's virtual disk 196 refers to
a zero cylinder displacement on volume SYS196.) 19:06:34 q virtual 19:06:40 STORAGE = 00256K 19:06:40 CONS 009 ON DEV 01F 19:06:40 RDR OOC CLS A 19:06:40 PUN OOD CLS A 19:06:40 PRT OOE CLS A 19:06:40 DASD 190 2314 CMS190 19:06:40 DASD 196 3330 SYS196 COpy 01 COpy 01 RIO 056 CYL RIO 010 CYL L--- ________________________________________ Again, the user signals attention to the virtual CP system. The
oFerator types in QUERY VIRTUAL, and the display is the virtual machine
configuraticn for the virtual machine operator. Note that the operator
has a ccnfiguration that is suitable for running CMS by loading (via IPL) virtual device 190. r---- I 19:07:38 att 131 operator 191 I 19:07:55 DASD 131 ATTACH TO OPERATOR 191
The operator attaches what appears to him as real disk 131 to himself
as virtual address 191. The response indicates a successful attach.
r I !! I CP I q v 131 I DASD 131 2314 CMS190 RIO 026 CYL The attention signalled here, shown by two exclamation marks followed by the werd CP, indicates that the user is at the real CP level. At
tbat level, issue a QUERY VIRTUAL 131. The response indicates that the
virtual 131 disk is a 2314 with read-only status, with 26 usable
cylinders.
64 IBM VM/370 operating systems in a Virtual Hachine

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