ARM Technical Support Knowledge Articles

How much trace can RealView-Trace capture ?

Applies to: RealView ICE and Trace (RVI / RVT)

Answer

The RealView-Trace has enough RAM space for 1 million records. Each record can contain a different number of trace samples, depending on how the trace unit is configured.

Each trace record is made up of 12 bytes, split into two 6 byte half records. With each half record 1 byte is reserved for future use, leaving a total of 5 bytes for storing trace samples. If RealView-Trace Timestamps are selected then the second half record is used for storing a 48 bit time stamp.

Examples:

If you are tracing a 16 bit ETM port, you can store 4 * 16 bit samples in each record.

If you are tracing a 4 bit ETM port, you can store 8 * 4 bit samples in each record.

If you are are tracing a 4 bit ETM port with Timestamps enabled, you can store 4 * 4 bit samples in one half record.

Note that the more packing of samples into the record, the less time stamp resolution you get if you are using timestamps e.g. you only get one time stamp for every 4 samples in 4 * 4 bit capture mode.

Some trace documentation references 'trace frames'. A trace frame is actually a single ETM port sample. In 4 * 4 bit capture mode, you can get 8 samples in one record, and the RVT contains 1 million records - hence a RealView-Trace unit can contain "up to 8 million frames".

Article last edited on: 2008-09-09 15:47:50

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