A method, computer program product, and distributed data processing system that allows a system image within a multiple system image virtual server to directly expose a portion, or all, of its associated system memory to a shared PCI adapter without having to go through a trusted component, such as a Hypervisor. Specifically, the present invention is directed to a mechanism for sharing conventional PCI I / O adapters, PCI-X I / O Adapters, PCI-Express I / O Adapters, and, in general, any I / O adapter that uses a memory mapped I / O interface for communications.