From: David Laight

Sent: 24 March 2021 09:12

From: Martin Sebor

quoted

Sent: 22 March 2021 22:08

...

quoted

In GCC 11, all access warnings expect objects to be either declared
or allocated.  Pointers with constant values are taken to point to
nothing valid (as Arnd mentioned above, this is to detect invalid
accesses to members of structs at address zero).

One possible solution to the known address problem is to extend GCC
attributes address and io that pin an object to a hardwired address
to all targets (at the moment they're supported on just one or two
targets).  I'm not sure this can still happen before GCC 11 releases
sometime in April or May.

A different solution is to define a normal C external data item
and then assign a fixed address with an asm statement or in
the linker script.

Or stop gcc tracking the value by using:
	struct foo *foo = (void *)xxxxx;
	asm ("", "+r" (foo));

If the address is used more than once forcing it into
a register is also likely to generate better code.

	David

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