> >> Sorry, why you still say this 'init_device_table_dma' can block DMA? >> I just think this function will enable DMA transfer, since we set >> the V and TV bits, right? or I misunderstand what "block DMA" mean? > > When the V and TV bits are not set, it means that all DMA from that > device-id is forwared untranslated by the IOMMU. But if we set V and TV > it means that there is translation information, and the IOMMU translates > the requests using the rest of the DTE information. As all other bits > are 0, this means that page-table-level is 0 (== no page-table) and that > the global IW and IR bits are 0 too (== no read and write permissions). > So all requests are blocked. >
Clearly. Thanks. > > > Joerg > > _______________________________________________ > iommu mailing list > io...@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu -- --- Vincent Wan(Zongshun) www.mcuos.com
