PRTB_SIZE_SHIFT
BUG_ON(PRTB_SIZE_SHIFT > 36);
process_tb = early_alloc_pgtable(1UL << PRTB_SIZE_SHIFT, -1, 0, 0);
dw1 = __pa(process_tb) | (PRTB_SIZE_SHIFT - 12) | PATB_GR;
0, PRTB_SIZE_SHIFT - 12);