Program Trace - STMicroelectronics SPC572L series Reference Manual

e200z215An3 Nexus 3 Module
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Note: OS updates to NPIDR should be performed in addition to normal PID0 updates when a
process switch occurs, in order to properly generate OTM messages with new process ID
information when NPIDR is selected for OTM use.
The process ID source (PID0 or NPIDR) is selected by the setting of the DC1
There are two conditions that will cause an Ownership Trace Message when Ownership
Trace is enabled:
•
When the PID0 register is written to by the processor and DC1
should be used, or when the NPIDR register is written to by the processor and DC1
indicates NPIDR should be used, the data is latched within Nexus, and is messaged
out via the auxiliary port, allowing development tools to trace ownership flow. However,
if Program Trace is enabled, and program correlation messages for PID updates are
not masked (Event Code = 0101), then an OTM will not be generated for an update to
the selected process ID register, since the program correlation message will provide
this process ID update information.
•
Periodically, at least once every 256 messages, the most recent state of the selected
process ID register is messaged out. The resulting Ownership Trace message will
indicate in the PID Index sub-field that PID0/NPIDR status is being reported and the
most recent value of the PID0/NPIDR register will be conveyed in the Process ID value
sub-field. These periodic Ownership Trace message events can be disabled by setting
DC1
Ownership trace information is messaged out in the following format:
66.12

Program Trace

This section details the program trace mechanism supported by Nexus3 for the
e200z215An3 processor. Program trace is implemented via Branch Trace Messaging (BTM)
as per the IEEE-ISTO 5001 standard definition. Branch Trace Messaging for Core
(e200z215An3) processors is accomplished by snooping the internal address bus, attribute
signals, and CPU Status (p_mode[0:3], p_pstat_pipe{0,1}[0:5]).
1950/2058
Nexus 3 Process ID
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
SPR — 517; Read/Write; Reset: 0
Figure 1161. Nexus 3 Process ID Register (NPIDR)
.
POTD
Figure 1162. Ownership Trace Message format
(1-32 bits)
Process ID
Variable length = 15–46 bits
DocID027809 Rev 4
(4 bits) (4 bits)
PID Index
Src. Proc.
(0000)
RM0400
control bit.
OTS
indicates PID0
OTS
OTS
(6 bits)
TCODE (000010)