If you want to give foo an absolute address, you surely don't want the linker to place other variables "around" it. Then, it is enough to treat foo as "any symbol", and simply assign it:

foo = 64
 

At the end of the day, this is what the compiler produces, too. This

__xdata __at 0x200 a[10];
__xdata b[10];

 

SDCC compiles to:

                             13 	.globl _b
                             14 	.globl _a
[...]
                             65 	.area XSEG    (XDATA)
                    0200     66 _a	=	0x0200
   0000                      67 _b::
   0000                      68 	.ds 20

 

(Note that the compiler adds underscores to its variables).

JW