What does the 'parent' of a memory region mean?

[xiaokaoy]

Hello.

I'm working with imx8dual. When running 'dump rm mem' command on scfw console, I got this

>$ dump rm mem
Partition: 0
000: 0x030FE0000 - 0x03101FFFF
Perms: 3000000xxxxxxxxxxxxx
Partition: 1
001: 0x000000000 - 0x01BFFFFFF
Perms: 0300033xxxxxxxxxxxxx
004: 0x080000000 - 0x08FFFFFFF
Perms: 0300033xxxxxxxxxxxxx
006: 0x092000000 - 0x09FFFFFFF
Perms: 0300033xxxxxxxxxxxxx
Partition: 2
Partition: 3
002: 0x034000000 - 0x037FFFFFF
Perms: 0007000xxxxxxxxxxxxx
Partition: 4
Partition: 5
003: 0x070000000 - 0x07FFFFFFF
Perms: 0700077xxxxxxxxxxxxx
005: 0x400000000 - 0x43FFFFFFF
Perms: 0700077xxxxxxxxxxxxx
008: 0x09FC00000 - 0x09FFFFFFF
Perms: 0700077xxxxxxxxxxxxx
Parent: 6
009: 0x092000000 - 0x09DFFFFFF
Perms: 0700077xxxxxxxxxxxxx
Parent: 6
010: 0x080020000 - 0x08FFFFFFF
Perms: 0700077xxxxxxxxxxxxx
Parent: 4
011: 0x000118000 - 0x01BFFFFFF
Perms: 0700077xxxxxxxxxxxxx
Parent: 1
Partition: 6
007: 0x090000000 - 0x091FFFFFF
Perms: 0707077xxxxxxxxxxxxx

My questions are:

What does 'parent' mean? AFAIK, a memory region has an owner rather than a parent.

In addition, some memory regions have a parent being showed, while others don't. Why?

[Zhiming_Liu]

Hi xiaokaoy

Q1:

This is related to the memory allocation algorithm. All dynamically requested memory is linked to a parent, and multiple dynamic memories are sibling.

Q2:

The SCFW configures xRDC and SMMU, it does not need access to all system
memory to achieve its purpose, only to the relevant registers involved. Those
are not in main memory. All it needs to do is apply the resource management to the SCU itself and it would work. Alternatively, it could configure the SCU MMU to limit its access to its own SRAM and the register regions it needs to do its work.

[xiaokaoy]

Thanks for your answer.