The Alpha EV7 On-Chip Logic Analyzer (OCLA) utility collects
Program Counter (PC) traces in a portion of the Alpha EV7 cache.
This data enables the user to tell which instructions each Alpha
EV7 CPU on the system has executed.
When entered by itself with no command keyword, the OCLA command
lists the OCLA command options.
SDA> OCLA
You can get full help on OCLA by entering HELP OCLA at the SDA>
prompt.
NOTE
When you use the ANALYZE/CRASH command to analyze a crash
dump, the only OCLA commands you can use are OCLA SHOW
STATUS and OCLA SHOW TRACE.
1 – Overview
OCLA enables the user to tell which instructions each Alpha EV7
CPU has executed by setting aside one seventh of the Alpha EV7
cache as acquisition memory which stores the virtual addresses
of instructions executed by the Alpha EV7 CPU. The acquisition
memory in the cache can later be analyzed with an SDA extension.
The acquisition of instructions can be enabled or disabled
while the system is running, thereby allowing the acquisition
of instruction streams for a given period of time without the
need to restart the system.
If the OCLA is enabled and started, and your system subsequently
fails due to a crash, the current acquisition memory is
automatically saved to the system dump file. The instructions
executed by each CPU prior to the system failure can then be
analyzed with SDA. Upon restart of the system, the acquisition
memory in the EV7 is still there and can be copied into system
memory using the OCLA ENABLE and OCLA DUMP commands.
If the STOP/CPU command is issued on a CPU for which OCLA has
been enabled, OCLA is automatically disabled if the CPU is
allowed to leave the active set. When a CPU is started with the
START/CPU command, OCLA is not automatically enabled; rather, it
must be enabled using SDA.
2 – DISABLE
Disables the OCLA and returns the cache set to the Alpha EV7 CPU.
Format
OCLA DISABLE [/CPU=n]
2.1 – Qualifier
2.1.1 /CPU
/CPU=n
Specifies the CPU on which OCLA should be disabled. If this
qualifier is omitted, OCLA is disabled on every CPU in the
system.
3 – DUMP
Copies the acquisition memory in the Alpha EV7 cache to a region
in system space for later analysis by SDA.
When a system fails, data collected in the EV7 cache is
automatically saved in the system dump file for each enabled
CPU. (See the OCLA SHOW TRACE command for more information.)
Format
OCLA DUMP [/CPU=n]
3.1 – Qualifier
3.1.1 /CPU
/CPU=n
Specifies the CPU for which to dump the acquisition memory. If
this qualifier is omitted, the acquisition memory is dumped for
all CPUs.
4 – ENABLE
Enables the OCLA. Reserves one-seventh of the EV7 cache as
acquisition memory for instructions.
Format
OCLA ENABLE [/CPU=n] [/RESET]
4.1 – Qualifiers
4.1.1 /CPU
/CPU=n
Specifies the CPU on which to enable OCLA. If this qualifier is
omitted, OCLA is enabled on every CPU in the system.
4.1.2 /RESET
Initializes the OCLA to default values.
Under certain circumstances, the OCLA might not be initialized
properly when the system is powered on. For more information, see
the OCLA SHOW REGISTER command.
If you wish to reset only certain registers to default values,
use the OCLA SET REGISTER/RESET command.
5 – HELP
Provides online help on OCLA commands.
Format
OCLA HELP
6 – LOAD
Loads the OCLA$PCTRACE execlet. This must be done before enabling
any OCLA.
Format
OCLA LOAD
7 – SET
7.1 – REGISTER
Resets a specified OCLA register to its default value.
The /RESET qualifier is required for this operation.
Format
OCLA SET REGISTER /RESET keyword
7.1.1 – Parameter
keyword
Specifies which OCLA register to reset to its default value. The
valid keywords are as follows:
MISC OCLA 1 miscellaneous register
OCLA1_CTL OCLA 1 control register
PC_CTL OCLA 1 PC control register
SMASK OCLA 1 select mask register
SMATCH OCLA 1 select match register
TMASK OCLA 1 trigger mask register
TMATCH OCLA 1 trigger match register
NOTE
You cannot reset all registers using a single command if
OCLA has already been enabled. You must first disable OCLA
using the OCLA DISABLE command. You can then reset all the
registers by performing an OCLA ENABLE/RESET command.
7.1.2 – Qualifier
7.1.2.1 /RESET
This qualifier is required to reset the specified register to its
default value.
8 – SHOW
8.1 – REGISTER
Displays detailed information about OCLA registers.
Format
OCLA SHOW REGISTER [/CPU=n]
8.1.1 – Qualifier
8.1.1.1 /CPU
/CPU=n
Specifies the CPU for which to display registers. If this
qualifier is omitted, registers are displayed for all CPUs.
8.2 – STATUS
Displays the status of an OCLA.
Format
OCLA SHOW STATUS [/CPU=n]
8.2.1 – Qualifier
8.2.1.1 /CPU
/CPU=n
Specifies the CPU for which to show OCLA status. If this
qualifier is omitted, status is displayed for all CPUs.
8.3 – TRACE
Decodes the acquired compressed instruction stream and displays
it.
Format
OCLA SHOW TRACE [/CPU=n] [/LAST=n][/NOPAL][/REVERSE][/SUMMARY][/SYMBOLIZE]
8.3.1 – Qualifiers
8.3.1.1 /CPU
/CPU=n
Specifies the CPU for which to show data. If this qualifier is
omitted, trace data is displayed for all CPUs.
8.3.1.2 /LAST
/LAST=n
Displays the last n instructions. If this qualifier is omitted,
trace data is displayed for all instructions.
8.3.1.3 /NOPAL
Do not include PAL code when displaying instructions.
8.3.1.4 /REVERSE
Displays the instructions in reverse order.
8.3.1.5 /SUMMARY
Displays the last 42 instructions.
8.3.1.6 /SYMBOLIZE
Attempts to symbolize each instruction.
9 – START
Starts the acquisition of instructions into acquisition memory.
Format
OCLA START [/CPU=n]
9.1 – Qualifier
9.1.1 /CPU
/CPU=n
The CPU on which to start instruction acquisition. If this
qualifier is omitted, instruction acquisition is started on all
CPUs.
10 – STOP
Stops the acquisition of instructions.
Format
OCLA STOP [/CPU=n]
10.1 – Qualifier
10.1.1 /CPU
/CPU=n
Specifies the CPU on which to stop acquisition. If this qualifier
is omitted, acquisition is stopped on all CPUs.
11 – UNLOAD
Unloads the OCLA$PCTRACE execlet and returns the acquisition
buffers to the system.
Format
OCLA UNLOAD