Booting from a different device to root. Pi 5

From	The Natural Philosopher <tnp@invalid.invalid>
Newsgroups	comp.sys.raspberry-pi
Subject	Booting from a different device to root. Pi 5
Date	2026-08-13 16:34 +0100
Organization	A little, after lunch
Message-ID	<115ko6u$1of94$1@dont-email.me> (permalink)

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Aim:

To use up some nice SATA SSDS  on a pi5.

The problem:

A Pi 5 doesn't support SATA without additional hardware.

So I have selected this:
https://suptronics.com/Raspberrypi/Storage/x1009-v1.1_software.html  ...
...SATA hat.

Unfortunately the SATA drives won't be available until [some part] of 
the boot sequence is completed.

Now I don't mind having the /boot partition on an SD but I really don't 
want the root file system there.

So I would like to force the pi to use [part of] one of the SATA drives 
as rootfs.

Opinions vary on whether this is possible,

Some say just put the right device [ssd root partition] in cmdline.taxt
Others imply that you also need to compile a kernel with static pci 
support because pci isn't available when the kernel is trying to load 
the rootfs
Others declare it is in fact completely impossible...

I *could* fall back to a USB connected SSD to run the root system and 
boot from.

Anyone know the truth, or otherwise?



-- 
The New Left are the people they warned you about.

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Thread

Booting from a different device to root. Pi 5 The Natural Philosopher <tnp@invalid.invalid> - 2026-08-13 16:34 +0100
  Re: Booting from a different device to root. Pi 5 John R Walliker <jrwalliker@gmail.com> - 2026-08-13 16:59 +0100
    Re: Booting from a different device to root. Pi 5 The Natural Philosopher <tnp@invalid.invalid> - 2026-08-13 17:13 +0100
  Re: Booting from a different device to root. Pi 5 druck <news@druck.org.uk> - 2026-08-13 22:06 +0100

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