I am junior embedded software engineer and new on developing with embedded systems, so this question may be a bit easy to answer. I'm currently working on MPC5644A eTPU and I noticed that MPC5644A don't use the all allocated size for eTPU Parameter RAM and eTPU Paramater RAM Mirror as shown in below.
I wonder that why we use just 3 Kbyte of 16Kbyte allocated size?
My guess is that this is due to possible future expansion, but no more then 6KB were needed in eTPU para RAM.
Also the block are usually aligned. What matters to you is that you have 3kB available.
I will check with design, but it can take some time.
A better or more detailed answer may come from NXP, but I believe the populated eTPU parameter and code memory sizes for each part are tradeoffs between space/cost/etc. constraints and allowing necessary applications to be supported in the eTPU software. Note that the table in your post doesn't state it, but the maximum eTPU code RAM possible would be 64KB. To my knowledge, no current part has an eTPU module populated with more than 6KB parameter RAM and 24KB code RAM.