Patent ID: 8639858

Claim:
A computer program product for managing address spaces in a computing environment, the computer program product including: a non-transitory computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: concurrent to an adapter accessing a direct memory access (DMA) address space located within system memory external to the adapter, performing a) and b): a) updating a DMA address space limit, based on executing, by a processor, a Modify PCI Function Controls (MPFC) instruction re-register function that includes a handle for locating an adapter, the MPFC instruction specifying a new DMA address space limit corresponding to the DMA address space, the new DMA address space limit representing a change in size of the DMA address space located within system memory, and wherein the new DMA address space limit is an explicit limit used by hardware to control a range of addresses defining the DMA address space; and b) informing the adapter that the DMA address space limit has changed, wherein based on a change in size of the DMA address space, the method further comprises: determining whether a number of levels of address translation tables is to be changed, based on the change in size of the DMA address space; and based on the determining, performing one of: based on determining the number of levels of address translation tables is to be changed, increasing or decreasing the number of levels of address translation tables; or based on determining the number of levels of address translation tables is not to be changed, maintaining the number of levels of address translation tables.