19.3.9. Using the CLCD window

When the AEMv8-A Base Platform FVP starts, the FVP CLCD window opens, representing the contents of the simulated color LCD frame buffer. It automatically resizes to match the horizontal and vertical resolution set in the CLCD peripheral registers.

Figure 19.6 shows the FVP CLCD in its default state, immediately after being started.

Figure 19.6. CLCD window at startup

CLCD window at startup

The top section of the CLCD window displays the following status information:

Total Instr

A counter showing the total number of instructions executed.

Total Time

A counter showing the total elapsed time, in seconds.

This is wall clock time, not simulated time.

Rate Limit

This option limits the rate of simulated time when the cores are in WFI, reset, or otherwise idle.

Rate Limit is enabled by default. Simulation time is restricted so that it more closely matches real time.

Click the square button to disable or enable Rate Limit. The text changes from ON to OFF and the colored box becomes darker when Rate Limit is disabled. Figure 19.7 shows the CLCD with Rate Limit disabled.


You can control whether Rate Limit is enabled by using the rate_limit-enable parameter, one of the visualization parameters for the AEMv8-A Base Platform FVP Visualization component, when instantiating the model.


Shows the number of instructions executed per second of wall clock time.

Perf Index

The ratio of real time to simulation time. The larger the ratio, the faster the simulation runs. If you enable the Rate Limit feature, the Perf Index approaches unity.

CLCD display

The large area at the bottom of the window displays the contents of the CLCD buffer, as in Figure 19.7.

Figure 19.7.  CLCD window active

CLCD window active

Table 19.2. Core run state icon descriptions

IconState labelDescription
UNKNOWNRun status unknown, that is, simulation has not started.
RUNNINGThe core is running, is not idle, and is executing instructions.
HALTEDAn external halt signal is asserted.
STANDBY_WFEThe last instruction executed was WFE, and standby mode has been entered.
STANDBY_WFIThe last instruction executed was WFI and standby mode has been entered.
IN_RESETAn external reset signal is asserted.
DORMANTPartial core power down.
SHUTDOWNComplete core power down.


The icons do not appear until you start the simulation.

You can hide the host mouse pointer by pressing the Left Ctrl+Left Alt keys. Press the keys again to redisplay the host mouse pointer. Only the Left Ctrl key is operational. The Ctrl key on the right-hand side of the keyboard does not have the same effect.

If you prefer to use a different key, use the trap_key configuration option, one of the visualization parameters for the Visualization component.

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