Changes

Once a log is obtained, it's recommended to contact your eMMC vendor to get more information about the log analysis tools required for analyzing the specific eMMC product.

Below is an example of how the TRACE32-based log method can be applied to a Linux system. The solution is based on light instrumentation of the <code>mmc_start_request()</code> and <code>mmc_request_done()</code> functions defined in the Linux <code>drivers/mmc/core/core.c</code> source code file. Relevant eMMC device accesses are captured through the instrumentation code and they are written to a static data structure making them immediately traceable if data trace is available in the SoC. If data tracing is not possible, the instrumentation code writes the data to the Arm®/Cortex® Context ID register.

NOTE: ‘OR Cycle task’ is optional.

In Linux, eMMC access log solutions based on purely software methods are already available. The <code>ftrace</code> framework provides this capability, as well as being able to log many other events. The term <code>ftrace</code> stands for “function tracer” and basically allows you to examine and record the execution flow of kernel functions. The dynamic tracing mode of <code>ftrace</code> is implemented through dynamic probes injected into the code, which allow the definition of the code to be traced at runtime. When tracing is enabled, all the collected data is stored by <code>ftrace</code> in a circular memory buffer. In the framework, there is a virtual filesystem called <code>tracefs</code> (usually mounted in <code>/sys/kernel/tracing</code>) which is used to configure <code>ftrace</code> and collect the trace data. All management is done with simple operations on the files in this directory.