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Status Future consideration
Workspace z/TPF Product Family
Categories z/TPF
Created by Guest
Created on Feb 18, 2025

RELATED IDEAS

Add support for signal shutdown in TPF under VM

  1. Enable the system to receive interrupts from the service processor
    1. Set a bit on in Control Reg 0
    2. Issue a SERVC instruction defining a small area in memory for the service processor to communicate to TPF
  2. Act on the receipt of the Ext 2401 interrupt:
    1. Issue a SERVC instruction to retrieve information from the service processor.
    2. Set an indicator that the shutdown signal was received.
    3. Create an ECB to do ZCYCL 1052
    4. When 1052 state is reached, and the shutdown signal was received  load the special PSW that tells the service processor “we’re shutdown” it’s safe to kill us now.
  3. There are 3 ways to get to 1052 state:
    1. System is restarting and coming up to 1052 state. We have checks there to start IUCV on VM
    2. The system may already be in 1052 state
    3. The system is in UTIL, CRAS or NORM state and is shutdown to 1052 state

 

It would be safe to have this in place even if TPF is not on VM, because this is supported by the LPAR hardware… if an LPAR is deactivated, the service processor will tell the OS “You need to shutdown”

But, we also have code within TPF that is only done if the system is on VM… so this could easily be omitted from prod/native systems. (It should be dynamic so if a native image is brought up on VM, it would be in effect, while native on native would not)

Idea priority Low
  • Guest
    Apr 29, 2025
    The design approach still needs to be completed but yes, operator awareness will be done. Our thinking is the z/TPF system will issue a message indicating the external 2401 interrupt was received. At design time it will be decided if the z/TPF system will issue any additional messages or if it will be the responsibility of the user exit.
    Reply
  • Guest
    Apr 16, 2025

    This sounds good to us.  There was one question though.

    Will the IBM-supplied code issue any messages to the console (PCRAS) when the interrupt happens?  Perhaps something like:

    1 – Shutdown signal ignored by user exit

    2 – Shutdown signal approved by user exit

    Reply
  • Guest
    Mar 20, 2025
    The z/TPF lab proposes cycling to 1052 state when the external 2401 interrupt is received and calling a user exit. The response from the user exit would indicate either 1) the system is to continue shutdown immediately, ending with the special PSW, or 2) the system is to ignore the shutdown signal and remain in 1052 state.

    The response from the user exit would likely be at least partially based on whether utilities are running. TPF would not shut down while utilities are running unless the user exit indicated that that is desired. And, given that utilities may take significantly longer to complete than the shutdown interval might allow, we would not implement a solution that continues to wait and repeatedly invoke the user exit until a "continue shutdown" response is received.

    Based on resources and other priorities, this is the solution proposed by the z/TPF lab. Does this solution satisfy your requirement?
    Reply

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