Good day.
I am reading the Arm®v7-M Architecture Reference Manual and I see this table in the memory access order
with a corresponding description of the access order.
Next I read the document ARM Cortex-M Programming Guide to Memory Barrier Instructions Application Note 321, which has exactly the same table, but there is a very important subtlety described in the text:"The Cortex-M processors never perform memory accesses out of order compared to instruction flow, however, the architecture does not prohibit this in future implementations."
That is, in Cortex-M4 the memory order is guaranteed by the implementation, and the table above must be filled entirely with "<" symbols. Right?
If so, why, for example, in the STM32 Cortex®-M4 MCUs and MPUs programming manual is there still a table like in the first picture, i.e. the document knows nothing about the strict ordering of memory accesses in the Cortex-M4 core implementation? Where is the truth?