Library /sys$common/syshlp/sda.hlb CPU Context  *Conan The Librarian (sorry for the slow response - running on an old VAX)

     In a uniprocessor system there exists only one CPU, and the concept
     of SDA CPU context is not an issue.  However, for a multiprocessor
     system with more than one active CPU, SDA must maintain an idea of
     CPU context to provide a way of displaying information bound to a
     specific CPU, such as the reason for the BUGCHECK exception, the
     currently executing process, the current IPL, the contents of CPU
     registers, the interrupt stack pointer (ISP), and any owned spinlocks.
     When SDA is first invoked to analyze a crash dump, the "SDA current
     CPU" is the CPU that induced the system failure.

     The CPU context will be changed as a result of several different SDA
     commands.  When the CPU context is changed, the "SDA current process"
     is changed to the current process on the "SDA current CPU" in order
     to keep CPU context and process context in synch.  If there is no
     current process on the "SDA current CPU", 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 PROCESS_CONTEXT for specific information about
     the "SDA current process".

     The following SDA commands will change the "SDA current CPU":

 	SET CPU cpu_id   ! Changes the "SDA current CPU" to CPU cpu_id

 	SHOW CPU cpu_id  ! Changes the "SDA current CPU" to CPU cpu_id

 	SHOW CRASH       ! Changes the "SDA current CPU" to the CPU
 			 ! that induced the system failure

     If a process is selected that is the current process on a CPU, the
     following commands will change the "SDA current CPU" to that CPU:

 	SET PROCESS process_name
 	SET PROCESS /INDEX=n
 	SHOW PROCESS process_name
 	SHOW PROCESS /INDEX=n

     No other SDA commands will affect the "SDA current CPU".

     Note:  When analyzing the running system, the SET CPU and SHOW CPU
            commands are not allowed, since SDA does not have access to
            all the CPU-specific information on the running system.