StorageTek 6 manual Master Trace Table Header, Trace Table Entries

Master Trace Table Header

A data area, called the Master Trace Table Header (MTTH) is a 32-byte header which describes the actual trace table. The address of the MTTH is in the 4-byte area at absolute address x’54’ (label TRCTAB in structure NUCON). The MTTH actually resides in the CVT at offset x’238’ (label CVTMTTH).

The format of the MTTH is:

	*-------------------------------------------				*
x’00’	MTTCURR	MTTFIRST	MTTLAST	reserved
	*-------------------------------------------				*
x’10’	MTTWRAP	MTTQCNT	MTTQLIM	‘MTT’
	*-------------------------------------------				*

MTTCURR the address of the current TTE (actually the last entry made)

MTTFIRST the address of first TTE MTTLAST the address of (byte after) last entry

MTTLAST the address of (byte after) last entry

MTTWRAP is the TOD (bytes 3-6) of last wrap (or first entry)

MTTQCNT is the number of events queued since POSTING (since TRACE task was

POSTed)

MTTQLIM is the number of events to queue before POSTING

MTTEYE is the eye catcher: c’MTT ‘

Trace Table Entries

Each trace table entry (TTE) is 32 bytes long. The default trace table size is 8k bytes (256 entries). All SCP events are recorded, regardless of the state of the external trace (SCP ‘TRACE command). ‘‘USR’’ events (GTRACE) events are never recorded in the SCP internal trace table. Instead, USR events generated by the HSC are recorded in the HSC internal trace table.

The TTE contains common information about every event, and some data specific to each event type.

* STANDARD TRACE TABLE ENTRY (TTE)

Offset	*------------------------------------------------					*
x’00’	PSW at the time of the event
	*------------------------------------------------					*
x’08’	event		event	TTEWORD1	( 4 bytes of
	type	flag code		event-dependent data)
	*------------------------------------------------					*
x’10’	TTEWORD2 ( 4 bytes of			TTEWORD3	( 4 bytes of
	event-dependent data)			event-dependent data)
	*------------------------------------------------					*
x’18’	TBLOK address			TOD (bytes 3-6)
	of current task			at time of event
	*------------------------------------------------					*

350VM/HSC 6.0 System Programmer’s Guide

1st ed., 6/30/04 - 312579601