Multi-core file IO test cases

[oyama]

• Design test cases
• Implement unit tests

[oyama]

littlefs-project/littlefs#483
http://elm-chan.org/fsw/ff/doc/appnote.html

Littlefs and FatFs do not support multiple opens to the same file. In the sense that it can be opened, but not with the expected results.

A case to consider is when file descriptors are passed from fifo and each core seeks the file before operating on it?

Parallel read/write to different files may be a realistic test.

[oyama]

https://forums.raspberrypi.com/viewtopic.php?t=311709

To update Flash from core1, functions need to be placed in RAM; SD and Heap block devices do not have this restriction.

[oyama]

When running with pico-sdk 1.5.1 and openocd, core1 needs to reset and sleep.
https://forums.raspberrypi.com/viewtopic.php?t=349795
This has been resolved in the develop branch

[oyama]

To access the flash in FreeRTOS with configNUMBER_OF_CORES > 1 configuration, the firmware must be run in RAM.