PR_PMLEN_MASK
unsigned long valid_mask = PR_PMLEN_MASK | PR_TAGGED_ADDR_ENABLE;
pmlen = FIELD_GET(PR_PMLEN_MASK, arg);
ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_7);
ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_16);
#ifndef PR_PMLEN_MASK
pmlen = (ret & PR_PMLEN_MASK) >> PR_PMLEN_SHIFT;