wˌɛn ɐn ˈɑːpɚɹˌeɪɾɪŋ sˈɪstəm ɪz ɹˈʌnɪŋ ɪnsˈaɪd ɐ vˈɜːtʃuːəl məʃˈiːn, ɪŋklˈuːdɪŋ sˈɪstəmz ðæt jˈuːs pˌæɹəvˌɜːtʃuːəlᵻzˈeɪʃən, sˈʌtʃ ɐz zˈɛn ænd kˌeɪvˌiːˈɛm, ɪt dʌznˌɑːt jˈuːʒuːəli nˈoʊ ðə hˈoʊstfˈɪzɪkəl ɐdɹˈɛsᵻz ʌv mˈɛmɚɹi ðˌɐɾɪt ˈæksɛsᵻz.
When an operating system is running inside a virtual machine, including systems that use paravirtualization, such as Xen and KVM, it does not usually know the host-physical addresses of memory that it accesses.