/sys$common/syshlp/SDA.HLB  —  Process Context
    In a uniprocessor system, there are two concepts related to SDA
    process context-the process that is current on the CPU, and
    the process in whose context process-specific SDA commands are
    interpreted. Either these two processes are the same, or they
    are not. However, for a multiprocessor system with more than one
    active CPU, the notion of SDA process context changes to provide
    a way of displaying information relevant to a specific process
    both when the process is current on some processor, and when the
    process is not.

    The SDA process context can be changed as a result of several
    different SDA commands. When the "SDA current process" is
    changed, the "SDA current CPU" is changed to that CPU to keep
    CPU context and process context synchronized. When the SDA CPU
    context is changed to a CPU that has no current process, the "SDA
    current process" is undefined, and no process context information
    will be available until SDA process context is set to a specific
    process. Type HELP CPU_CONTEXT for specific information about the
    "SDA current CPU".

    The SDA commands SET PROCESS, SHOW PROCESS, and VALIDATE PROCESS
    all change the "SDA current process" to be the process specified
    by one of the following:

    process_name     Changes the "SDA current process" to the process
                     specified by process_name.

    /ADDRESS=x       Changes the "SDA current process" to the process
                     with PCB address x.

    /INDEX=n         Changes the "SDA current process" to the process
                     with index n.

    /NEXT            Changes the "SDA current process" to the next
                     process in the system's process list.

    /SYSTEM          Changes the "SDA current process" to the system
                     process.

    The following commands change the SDA process context if the "SDA
    current process" is not the current process on the selected CPU:

    SET CPU cpu_id   Changes the "SDA current process" to the current
    SHOW CPU cpu_id  process on CPU cpu_id.

    SHOW CRASH       Changes the "SDA current process" to the current
                     process on the CPU that induced the system
                     failure.

    No other SDA commands affect the "SDA current process".

                                   NOTE

       When analyzing a running system, CPU context is not
       used because all the CPU-specific information may not be
       available.
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