One more question about interrupts

Interrupt gates are set in linux as 

set_intr_gate(i, interrupt[i-FIRST_EXTERNAL_VECTOR]);
                           ^
                           but the 'interrupt' is declared as 

extern void (*__initconst interrupt[NR_VECTORS-FIRST_EXTERNAL_VECTOR])(void);

can anyone possibly tell when are these enteries filled with valid pointers ???