Minor feature for ld

[Ian Lance Taylor]

Pete Gonzalez <pgonzalez@bluel.com> writes:

> I think the linker should support segments whose address is a
> function of the segment name.  It would allow definitions like
> this in GCC:
> 
>    __attribute__((section("/0x123456/"))) int IOPort;
> 
> In the above example, the linker would locate the variable at
> the given address, so these two statements would be equivalent:
> 
>    IOPort = x;
>    *(int *)0x123456 = x;
> 
> Really this feature belongs in the compiler, but sections are
> the closest C/C++ compilers come to letting you control the
> address of variables.  Everything else is handled by the linker,
> so that seems like the simplest place to fix.  (If not, maybe
> I should be pestering the GCC people.)

It's easy enough to do this in C by doing
    int* IOPort = (int*) 0x123456;
    *IOPort = x;

In most uses you will want volatile, as in
    volatile int* IOPort = (int*) 0x123456;

What's the advantage of doing it in a linker section?

Ian