MERGING DIRECT MEMORY ACCESS WINDOWS

摘要

A computing device may merge two translation tables used when performing a DMA operation into a single, combined translation table. To merge the translation tables, the computing device may update a register in the IOMMU to include a pointer to the combined translation table. In addition, the IOMMU may clear one of the registers from having a pointer to one of the merged translation table. Doing so means the entries in this translation table are now no longer assigned. The IOMMU may update the register with the pointer to the combined translation table to include the unassigned entries in the combined translation table. In this manner, the entries from the two translation tables are merged into the single, combined table. The combined translation table may be owned or assigned to a service provider that originally owned one of the merged translation tables or to a completely different service provider.

主权项

1. A method comprising:
determining to merge a first direct memory access (DMA) translation table assigned to a first service provider and a second DMA translation table assigned to a second service provider into a combined translation table, the combined translation table performing a virtual address to physical address translation for accessing data stored in respective DMA windows which define respective portions of memory in a computing system; updating a pointer in a first register of a plurality of registers that previously referenced the first translation table to reference the combined translation table; clearing a pointer in a second register of the plurality of registers that previously referenced the second translation table; and assigning the combined translation table to the first service provider, wherein the first service provider uses the combined translation table to perform DMA operations between an I/O adapter and one of the DMA windows.