FIFO overflow protection

FIFO overflow protection

The ETM contains a FIFO buffer that holds the traced data for transmission through the trace port. When this FIFO buffer becomes full, trace information is lost unless you have programmed the ETM to stall (temporarily stop) the processor. The options in this section of the dialog enable you to protect against FIFO overflows.

Select one of the following options:

No protection

Select this option if you do not want to use FIFO overflow protection.

Stall processor

Select this option if you want the system to stall the processor until the FIFO buffer is empty. You must also set FIFO highwater by typing a value into the text box. When the number of bytes left in the FIFO buffer is reduced to the number of bytes you set in FIFO highwater, the processor stalls as soon as possible. It restarts when the FIFO buffer is empty.

This capability is not supported by all systems. See the documentation that accompanies your system to find out whether FIFOFULL is implemented.

Data suppression

Select this option to instruct RealView Debugger to stop tracing data when the FIFO is close to the overflow limit. This helps to prevent a FIFO overflow, because the bandwidth required for instruction tracing is much lower than that required for data tracing.

A status line is displayed when data is being suppressed, and again when data is unsuppressed.

This option is available only for ETMv3 targets, and is grayed out for all other targets.