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Date:      Sun, 11 Feb 2024 10:58:56 -0800
From:      Mark Millard <marklmi@yahoo.com>
To:        Mario Marietto <marietto2008@gmail.com>
Cc:        freebsd-arm <freebsd-arm@freebsd.org>, FreeBSD Mailing List <freebsd-questions@freebsd.org>, freebsd-hackers <freebsd-hackers@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>, Warner Losh <imp@bsdimp.com>
Subject:   Re: How to use the L4 Microkernel with a FreeBSD userland.
Message-ID:  <071E080E-C0E6-40F0-A0DF-4FCC22FC004D@yahoo.com>
In-Reply-To: <CA%2B1FSijq0ez9%2BJXCSJP2rfWUXLjcTaEPJo-3NcO5Vu3H26L=hg@mail.gmail.com>
References:  <CA%2B1FSijq0ez9%2BJXCSJP2rfWUXLjcTaEPJo-3NcO5Vu3H26L=hg@mail.gmail.com>

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On Feb 11, 2024, at 05:44, Mario Marietto <marietto2008@gmail.com> =
wrote:

> I'm trying to understand how to use the L4 Microkernel with a FreeBSD =
userland. I've asked the same to a L4 developer,but he told me that he =
does not know FreeBSD,so I'm here to ask the same question. First of all =
I'm sure that it can be done,because it is written clearly on their =
website :
>=20
>=20
> http://os.inf.tu-dresden.de/L4Re/download/snapshots/
>=20
>=20
> on the section :
> Host system requirements
> The host system shall be a 64bit-based system with a recent Linux =
distribution installed and at least 2GB of free disk space.
> All necessary tools required by the build are available from the =
provided packages of the Linux distributions, including cross compilers. =
But there are also other cross compiler packages available (see below). =
You might want to run make check_build_tools in the src/l4 directory to =
verify the common tools are installed.
> You are free to use any Linux distribution you like, or even BSDs or =
any of its derivatives. But then you should know the game. Especially =
tool versions should be recent, as installed on the listed distributions =
below.
> We are confident that the snapshot works on the following =
distributions:
>     =E2=80=A2 Debian 11 or later
>     =E2=80=A2 Ubuntu 22.04 or later
>=20
> Let's say I want to use the L4 microkernel + FreeBSD 14 on my =
Raspberry Pi 4,the first step I did was to build L4Re for the =
Rpi,according with this instructions :
>=20
>=20
> http://os.inf.tu-dresden.de/L4Re/rpi.html=20
>=20
> This is the log file of the compilation,that hasn't given any  error :
>=20
>=20
> https://pastebin.ubuntu.com/p/6SwN2mpJBM/
>=20
>=20
> Or I could have taken a pre built image of the L4 microkernel here :=20=

>=20
>=20
> http://os.inf.tu-dresden.de/download/snapshots/pre-built-images/arm64/
>=20
>=20
>=20
> At this point the tutorial says that I should use a Linux distro. They =
suggest the official distro for the Raspberry Pi 4,that's RaspBian. But =
I don't want to use Linux as a userland,I want to use FreeBSD. The =
question now is : what should I do to achieve that goal ? How can I link =
the L4 microkernel with the ubldr bootloader of FreeBSD ? Or should I =
link it to the kernel of FreeBSD ? Can someone explain to me the missing =
step ? thanks.

QUOTING the "Configuring yourself" section:
The make setup step configures predefined setups for both the L4Re =
microkernel (Fiasco) and the L4Re user-level software, and connects both =
together so the images for the target system can be built.
END QUOTE

So L4Re has its own user-level software, not just a kernel. There is no =
use of a Linux or FreeBSD user-level software
when L4Re is booted. (They are just used for building.)

"The host system" is just a host for building the L4Re parts and =
assembling the image from the parts. The "Pulling it together" section =
is about combining the parts (including the microkernel and the =
user-level software) to make the overall image that does not include =
Linux or FreeBSD code.


=3D=3D=3D
Mark Millard
marklmi at yahoo.com




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