checking the state of devices during boot when debugging device
drivers, etc.
+config CMD_IOTRACE
+ bool "iotrace - Support for tracing I/O activity"
+ help
+ Provides an 'iotrace' command which supports recording I/O reads and
+ writes in a trace buffer in memory . It also maintains a checksum
+ of the trace records (even if space is exhausted) so that the
+ sequence of I/O accesses can be verified.
+
+ When debugging drivers it is useful to see what I/O accesses were
+ done and in what order.
+
+ Even if the individual accesses are of little interest it can be
+ useful to verify that the access pattern is consistent each time
+ an operation is performed. In this case a checksum can be used to
+ characterise the operation of a driver. The checksum can be compared
+ across different runs of the operation to verify that the driver is
+ working properly.
+
+ In particular, when performing major refactoring of the driver, where
+ the access pattern should not change, the checksum provides assurance
+ that the refactoring work has not broken the driver.
+
+ This works by sneaking into the io.h heder for an architecture and
+ redirecting I/O accesses through iotrace's tracing mechanism.
+
+ For now no commands are provided to examine the trace buffer. The
+ format is fairly simple, so 'md' is a reasonable substitute.
+
+ Note: The checksum feature is only useful for I/O regions where the
+ contents do not change outside of software control. Where this is not
+ suitable you can fall back to manually comparing the addresses. It
+ might be useful to enhance tracing to only checksum the accesses and
+ not the data read/written.
+
config CMD_LOADB
bool "loadb"
default y
projects / u-boot / commitdiff