bc_wback_inv
void (*bc_wback_inv)(unsigned long page, unsigned long size);
bcops->bc_wback_inv(page, size);
bc_wback_inv(addr, size);
.bc_wback_inv = (void *)cache_noop,
.bc_wback_inv = indy_sc_wback_invalidate,
.bc_wback_inv = mips_sc_wback_inv,
.bc_wback_inv = r5k_dma_cache_inv_sc,
.bc_wback_inv = rm7k_sc_wback_inv,