SBA_INLINE void sba_mark_invalid (struct ioc * ioc, dma_addr_t iova, size_t byte_cnt);
Marking the IO PDIR entry(ies) as Invalid and invalidate corresponding IO TLB entry. The PCOM (Purge Command Register) is to purge stale entries in the IO TLB when unmapping entries.
The PCOM register supports purging of multiple pages, with a minium of 1 page and a maximum of 2GB. Hardware requires the address be aligned to the size of the range being purged. The size of the range must be a power of 2. The ``Cool perf optimization'' in the allocation routine helps keep that true.