The hypervisor, upon receiving the ALDR registration request from AIX, saves the location and size of each item
into PHYP’s internal data-structures. It will then internally mark the LPAR as ALDR-enabled, so that a future OS crash detected will automatically load and trigger ALDRAIX into action. The hypervisor saves the address locations of ALDR-AIX’s boot image, initial register values, IPCLB,and ALDR item table. When the OS crashes, PHYP must copy the ALDR-AIX image into the VRMA. The reason for this copying is that ALDR-AIX has to access memory in translation-off mode during its boot time, whereas the higher memory location where ALDR-MemArea resides cannot be accessed in translation-off mode.