u-boot vs installer images

[Rainer Dorsch <ml@bokomoko.de>]

Hi,

I just browsed through the bullseye installation guide. I saw there is a 
section on 

3.6.2. Debian-provided U-Boot (system firmware) images
https://www.debian.org/releases/testing/armhf/ch03s06.en.html

and

5.1.5. Using pre-built SD-card images with the installer
https://www.debian.org/releases/testing/armhf/ch05s01.en.html

I am just wondering if I use a pre-built SD-card images with the installer do 
I still need the U-Boot (system firmware) images (I do not recall that I used 
them previously)? If not, what is the intended usecase for the U-Boot (system 
firmware) images?

Many thanks
Rainer

-- 
Rainer Dorsch
http://bokomoko.de/