Volatile Struct Semantics
In your example, the two are the same. But the issues revolve around pointers.
First off, volatile uint8_t *foo; tells the compiler the memory being pointed to is volatile. If you want to mark the pointer itself as volatile, you would need to do uint8_t * volatile foo;
And that is where you get to the main differences between marking the struct as volatile vs marking individual fields. If you had:
typedef struct{ uint8_t *field;} foo;volatile foo f;That would act like:
typedef struct{ uint8_t * volatile field;} foo;and not like:
typedef struct{ volatile uint8_t *field;} foo;