User`s manual

Special Topics
5-2 Single Board Computers SCSI Software UserÕs Manual
5
After logging is enabled, a user calls sdt_alloc() to get a pointer to the next entry
to be used for debug logging. A user makes this call from within a section of
code which is suspected to introduce problems or when critical information is
available to be saved in the log.
The final step in debug logging is retrieval and analysis of the logged
information. This is done after a problem has occurred and the user is trying
to determine the source of that problem.
Debug Trace Memory Structure
The following figure is a memory diagram of the debug trace log and is
intended to show the order of trace entry allocation.
On the first sdt_alloc() call, the current pointer is equal to the start location
current pointer towards the low end of memory, one frame at a time, until the
special first entry is reached. When the special first entry is reached, a
wraparound condition exists and the
current pointer will again be set to
start.