prom_allocate_virt
virt = prom_allocate_virt(align, size);
if ((virt = prom_allocate_virt((u_int)1, size)) == 0)
extern caddr_t prom_allocate_virt(uint_t align, size_t size);
virt = prom_allocate_virt(align, (size_t)align);
extern caddr_t prom_allocate_virt(uint_t align, size_t size);
extern caddr_t prom_allocate_virt(uint_t align, size_t size);