A method, apparatus, and computer program product dynamically allocate limited system memory for direct memory access (DMA) among a plurality of input/output (I/O) adapters in a system partition. Initially a minimum entitlement of I/O entitled memory capacity is allocated to each of the respective multiple I/O adapters. The minimum entitlement enables operation of an I/O adapter driver. Additional entitlement of I/O entitled memory capacity is selectively allocated based upon I/O demands of each I/O adapter.