+- I/O tracing:
+ When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
+ accesses and can checksum them or write a list of them out
+ to memory. See the 'iotrace' command for details. This is
+ useful for testing device drivers since it can confirm that
+ the driver behaves the same way before and after a code
+ change. Currently this is supported on sandbox and arm. To
+ add support for your architecture, add '#include <iotrace.h>'
+ to the bottom of arch/<arch>/include/asm/io.h and test.
+
+ Example output from the 'iotrace stats' command is below.
+ Note that if the trace buffer is exhausted, the checksum will
+ still continue to operate.
+
+ iotrace is enabled
+ Start: 10000000 (buffer start address)
+ Size: 00010000 (buffer size)
+ Offset: 00000120 (current buffer offset)
+ Output: 10000120 (start + offset)
+ Count: 00000018 (number of trace records)
+ CRC32: 9526fb66 (CRC32 of all trace records)
+