2) Create a new IPLCB (Initial Program Load Control Block) tailored for ALDR-AIX’s use, based on the IPLCB of the original running AIX instance.
The IPLCB is a data structure that contains all the configuration information necessary for the kernel initialization.
The aldrEnable command significantly trims the main OS’s IPLCB so that the repair image will see only the limited amount of resources that it can use. For example, running on only one hardware thread, accessing a limited amount of memory, and not being able to access any IO devices except the system console.