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Date:      Thu, 2 Oct 2025 09:47:11 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        ziaee@freebsd.org, dev-commits-src-main@freebsd.org
Subject:   RE: git: 2f7a796b590e - main - thunderbolt.4: Initial manual for HW Relnotes
Message-ID:  <1F1B3FF4-A31E-4E9C-8CFC-7BB7F1A38AFD@yahoo.com>
References:  <1F1B3FF4-A31E-4E9C-8CFC-7BB7F1A38AFD.ref@yahoo.com>

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Alexander Ziaee <ziaee_at_FreeBSD.org> wrote on
Date: Thu, 02 Oct 2025 15:14:07 UTC :

> The branch main has been updated by ziaee:
>=20
> URL: =
https://cgit.FreeBSD.org/src/commit/?id=3D2f7a796b590e67c5d123f2b00b3aaf7b=
a7a32a13
>=20
> commit 2f7a796b590e67c5d123f2b00b3aaf7ba7a32a13
> Author: Alexander Ziaee <ziaee@FreeBSD.org>
> AuthorDate: 2025-10-02 12:05:25 +0000
> Commit: Alexander Ziaee <ziaee@FreeBSD.org>
> CommitDate: 2025-10-02 15:12:48 +0000
>=20
> thunderbolt.4: Initial manual for HW Relnotes
>=20
> This manual contains nothing and is only suitable for the HW Relnotes,
> but lets get it in so we have something and then can iterate on it.
>=20
> MFC after: 3 minutes
> Fixes: 2ed9833791f2 (thunderbolt: Import USB4 code)
> Discussed with: obiwac
> Differential Revision: https://reviews.freebsd.org/D52847
> ---
> share/man/man4/Makefile | 1 +
> share/man/man4/thunderbolt.4 | 22 ++++++++++++++++++++++
> 2 files changed, 23 insertions(+)
>=20
> diff --git a/share/man/man4/Makefile b/share/man/man4/Makefile
> index f5d7a0e081fc..6e076722c786 100644
> --- a/share/man/man4/Makefile
> +++ b/share/man/man4/Makefile
> @@ -589,6 +589,7 @@ MAN=3D aac.4 \
> tdfx.4 \
> termios.4 \
> textdump.4 \
> + thunderbolt.4 \
> ti.4 \
> timecounters.4 \
> tmpfs.4 \
> diff --git a/share/man/man4/thunderbolt.4 =
b/share/man/man4/thunderbolt.4
> new file mode 100644
> index 000000000000..3477c11fb60d
> --- /dev/null
> +++ b/share/man/man4/thunderbolt.4
> @@ -0,0 +1,22 @@
> +.\"
> +.\" Copyright (c) 2025 Alexander Ziaee
> +.\"
> +.\" SPDX-License-Identifier: BSD-2-Clause
> +.\"
> +.Dd October 2, 2025
> +.Dt THUNDERBOLT 4
> +.Os
> +.Sh NAME
> +.Nm thunderbolt
> +.Nd USB4 controller driver
> +.Sh SYNOPSIS
> +.Cd device thunderbolt
> +.Sh HARDWARE
> +The
> +.Nm
> +driver supports USB4 controllers.

As I understand things, being fairly explicit related the
following is likely required (not a proposed wording or
presentation):

Quoting USB4 V2: "A USB4 Host or USB4 Peripheral Device can
optionally support interoperability with Thunderbolt 3
(TBT3) products."

Quoting USB4 V1: "A USB4 host or USB4 peripheral device can
optionally support interoperability with Thunderbolt 3
(TBT3) products."

In both, this is tied to Chapter 13, "Interoperability with
Thunderbolt(tm) 3 systems". As I understand FreeBSD is not
trying to meet the criteria in that chapter, for example.

USB4 does not require a certification process, as I
remember. Thunderbolt 4 and 5 do, as I remember.

As I remember, a distinction between USB4 and Thunderbolt 4
and 5 was that Thunderbolt 4 and 5 require (nearly?) all
optional items from the matching USB4 version to be
implemented (so: not optional if Thunderbolt 4 or 5 is
claimed/certified). Also, it seems unlikely that FreeBSD
would go through a Thunderbolt 4 or 5 certification process.

Overall this seems to mean not meeting the Thunderbolt 4
and/or 5 criteria fully and not supporting Thunderbolt 3
--but just meeting the criteria for one or both of:

) USB4 V1 without "TBT3" support
) USB4 V2 without "TBT3" support

That would be a subset of the Thunderbolt 4 or 5 criteria
in a way that excludes Thunderbolt 3.

Referencing Thunderbolt without someplace being fairly
explicit about those types of relationships could easily
leave a misimpression (even if I've gotten some of the
status wrong above).

My guess here is that enough is known about the intent
in this area to be able to have material about this type
of thing in place at any time.

> +.Sh HISTORY
> +The
> +.Nm
> +driver appeared in
> +.Fx 15.0 .
>=20

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




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