Hi,
The C++20 standard has deprecated a lot of volatile use. Therefore, a
lot of warnings pop-up in the compile, especially in hal/hal.h:
warning: ‘volatile’-qualified parameter is deprecated [-Wvolatile]
in lines 869, 879, 890, 900, 905,910, 915, 921
Same warning in hal/hal_priv.h:489.
The warnings originate from the typedef of hal_port_t (an offset into
shared memory) in hal/hal.h:323:
typedef volatile int hal_port_t;
The volatile modifier is used in the function prototypes' arguments,
which now emits the warning.
I do not understand /why/ volatile is used /at all/. The port,
apparently, always gets converted to a pointer using SHMPTR(), which
returns a *non-volatile* pointer-type. So there is no point in having
the argument declared volatile when all subsequent use drops the
modifier by forcefully having cast'ed it into something else.
If there should be any use of volatile, then it would be the
pointer-deref type returned by SHMPTR() because that addresses shared
memory (which may be altered concurrently). But volatile isn't used for
the actual target address and I cannot see how declaring the pre-cast
variable as volatile can have any effect on a post-cast non-volatile
dereference. Therefore, in my opinion, it does not work as intended.
I think it should be fixed by removing the volatile modifier from the
typedefs (hal/hal.h:318-323). Then the casts into shared memory should
add the volatile modifier so that reads and writes to shared memory are
performed when the code says it should be (non-cache'able in the program).
Any thoughts or insights from hal code veterans?
--
Greetings Bertho
(disclaimers are disclaimed)
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