1. 21 6月, 2014 1 次提交
    • S
      Add an I/O tracing feature · aa53233a
      Simon Glass 提交于
      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.
      
      Add an I/O tracing feature and associated commands to provide this facility.
      It works by sneaking into the io.h heder for an architecture and redirecting
      I/O accesses through its 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.
      Signed-off-by: NSimon Glass <sjg@chromium.org>
      aa53233a
  2. 19 6月, 2014 39 次提交