Not a command reject if they answer roll call saying that they are a
3480-04. They must accept any command that is valid for that device and
do something harmless if it is not one of their 5. The Command Reject
should be reserved for commands not in use by a real 3480. They cannot
legitimately claim to function as a specific device type and not accept
the CCWs that are valid for that device. I don't care what they do with
the unused commands. In most , if not all, cases, an immediate Device
End would be appropriate.
Regards,
Richard Schuh
________________________________
From: The IBM z/VM Operating System
[mailto:[EMAIL PROTECTED] On Behalf Of Mike Walter
Sent: Thursday, June 26, 2008 11:20 AM
To: [email protected]
Subject: Re: Tape Unit Documentation
IMHO, that's a bass-ackwards solution.
If they only handle 5 CCWs, then they should issue, at worst, a
Command Reject for anything else. Good Grief!
If they refuse, find out what they accept, and then give them a
list of the other 251 hex codes to ignore. You'd think they could count
that high?
Mike Walter
Hewitt Associates
Any opinions expressed herein are mine alone and do not
necessarily represent the opinions or policies of Hewitt Associates.
"Schuh, Richard" <[EMAIL PROTECTED]>
Sent by: "The IBM z/VM Operating System" <[email protected]>
06/26/2008 12:35 PM
Please respond to
"The IBM z/VM Operating System" <[email protected]>
To
[email protected]
cc
Subject
Tape Unit Documentation
We have a vendor that produces a device that responds to the IPL
roll call saying it is a 3480-04; however, it only uses a subset of the
tape unit's CCWs. If these devices receive a CCW that is not in their
list of 5 that they use, bad things, such as streamed unsolicited
interrupts or Command Rejects, happen. A detach of one of the devices
results in the streamed unsolicited interrupts which in turn causes the
device to be Boxed. Other commands like the forward or backward space
commands or Read Backward cause a Unit Check/Command Reject to be
reflected to the guest. I would like to be able to provide them with a
complete list of commands for which they should not cause irreparable
harm to the guest. Where can I find documentation showing the complete
list of CCWs used by real 3480 and 3490 devices?
Regards,
Richard Schuh
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