As an extension, the GNU C compiler supports named address spaces as
defined in the N1275 draft of ISO/IEC DTR 18037. Support for named
address spaces in GCC will evolve as the draft technical report changes.
Calling conventions for any target might also change. At present, only
the SPU and M32C targets support other address spaces. On the SPU target, for
example, variables may be declared as belonging to another address space
by qualifying the type with the
__ea address space identifier:
extern int __ea i;
When the variable
i is accessed, the compiler will generate
special code to access this variable. It may use runtime library
support, or generate special machine instructions to access that address
__ea identifier may be used exactly like any other C type
volatile). See the N1275
document for more details.
On the M32C target, with the R8C and M16C cpu variants, variables
__far are accessed using 32-bit addresses in
order to access memory beyond the first 64k bytes. If
used with the M32CM or M32C cpu variants, it has no effect.