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Date:      Thu, 22 Feb 2024 13:10:48 -0700
From:      Warner Losh <imp@bsdimp.com>
To:        John Baldwin <jhb@freebsd.org>
Cc:        Andrew Turner <andrew@freebsd.org>, src-committers@freebsd.org,  dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org
Subject:   Re: git: 47e073941f4e - main - Import the kernel parts of bhyve/arm64
Message-ID:  <CANCZdfpqFkGXkB6nu-ZZvk6XKoRGJu4-4ZqThLYFLyXx7dX8ig@mail.gmail.com>
In-Reply-To: <23101a96-4901-4086-bdbf-dfbab2b66e49@FreeBSD.org>
References:  <202402211855.41LItsm2033633@gitrepo.freebsd.org> <23101a96-4901-4086-bdbf-dfbab2b66e49@FreeBSD.org>

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On Thu, Feb 22, 2024 at 11:30=E2=80=AFAM John Baldwin <jhb@freebsd.org> wro=
te:

> On 2/21/24 10:55 AM, Andrew Turner wrote:
> > The branch main has been updated by andrew:
> >
> > URL:
> https://cgit.FreeBSD.org/src/commit/?id=3D47e073941f4e7ca6e9bde3fa65abbfc=
fed6bfa2b
> >
> > commit 47e073941f4e7ca6e9bde3fa65abbfcfed6bfa2b
> > Author:     Andrew Turner <andrew@FreeBSD.org>
> > AuthorDate: 2024-01-09 15:22:27 +0000
> > Commit:     Andrew Turner <andrew@FreeBSD.org>
> > CommitDate: 2024-02-21 18:55:32 +0000
> >
> >      Import the kernel parts of bhyve/arm64
> >
> >      To support virtual machines on arm64 add the vmm code. This is
> based on
> >      earlier work by Mihai Carabas and Alexandru Elisei at University
> >      Politehnica of Bucharest, with further work by myself and Mark
> Johnston.
> >
> >      All AArch64 CPUs should work, however only the GICv3 interrupt
> >      controller is supported. There is initial support to allow the GIC=
v2
> >      to be supported in the future. Only pure Armv8.0 virtualisation is
> >      supported, the Virtualization Host Extensions are not currently
> used.
> >
> >      With a separate userspace patch and U-Boot port FreeBSD guests are
> able
> >      to boot to multiuser mode, and the hypervisor can be tested with t=
he
> >      kvm unit tests. Linux partially boots, but hangs before entering
> >      userspace. Other operating systems are untested.
> >
> >      Sponsored by:   Arm Ltd
> >      Sponsored by:   Innovate UK
> >      Sponsored by:   The FreeBSD Foundation
> >      Sponsored by:   University Politehnica of Bucharest
> >      Differential Revision:  https://reviews.freebsd.org/D37428
>
> FYI, sys/arm64/vmm/vmm.c shares a fair bit of code with sys/amd64/vmm/vmm=
.c
> and looks to be derived from the amd64 file, so I think it should preserv=
e
> NetApp's copyright line in addition to Mihai's.
>

In general, the advice I've been giving is that one should retain
copyrights when
there's at least 10%-20% remaining of the original work. And one should
hesitate to add
them unless you've contributed 10%-20% or more to the work (ideally more,
but sometimes
that's gets squishy because the underlying law is based on words like
substantial
and de-minimus, which don't translate well to line counts, and for large
works what
is substantial can be a bit subjective).

If they share so much, maybe we should also look at sharing directly,
rather than by
cut and paste in the future.

Warner

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote">=
<div dir=3D"ltr" class=3D"gmail_attr">On Thu, Feb 22, 2024 at 11:30=E2=80=
=AFAM John Baldwin &lt;<a href=3D"mailto:jhb@freebsd.org">jhb@freebsd.org</=
a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0p=
x 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On=
 2/21/24 10:55 AM, Andrew Turner wrote:<br>
&gt; The branch main has been updated by andrew:<br>
&gt; <br>
&gt; URL: <a href=3D"https://cgit.FreeBSD.org/src/commit/?id=3D47e073941f4e=
7ca6e9bde3fa65abbfcfed6bfa2b" rel=3D"noreferrer" target=3D"_blank">https://=
cgit.FreeBSD.org/src/commit/?id=3D47e073941f4e7ca6e9bde3fa65abbfcfed6bfa2b<=
/a><br>
&gt; <br>
&gt; commit 47e073941f4e7ca6e9bde3fa65abbfcfed6bfa2b<br>
&gt; Author:=C2=A0 =C2=A0 =C2=A0Andrew Turner &lt;andrew@FreeBSD.org&gt;<br=
>
&gt; AuthorDate: 2024-01-09 15:22:27 +0000<br>
&gt; Commit:=C2=A0 =C2=A0 =C2=A0Andrew Turner &lt;andrew@FreeBSD.org&gt;<br=
>
&gt; CommitDate: 2024-02-21 18:55:32 +0000<br>
&gt; <br>
&gt;=C2=A0 =C2=A0 =C2=A0 Import the kernel parts of bhyve/arm64<br>
&gt;=C2=A0 =C2=A0 =C2=A0 <br>
&gt;=C2=A0 =C2=A0 =C2=A0 To support virtual machines on arm64 add the vmm c=
ode. This is based on<br>
&gt;=C2=A0 =C2=A0 =C2=A0 earlier work by Mihai Carabas and Alexandru Elisei=
 at University<br>
&gt;=C2=A0 =C2=A0 =C2=A0 Politehnica of Bucharest, with further work by mys=
elf and Mark Johnston.<br>
&gt;=C2=A0 =C2=A0 =C2=A0 <br>
&gt;=C2=A0 =C2=A0 =C2=A0 All AArch64 CPUs should work, however only the GIC=
v3 interrupt<br>
&gt;=C2=A0 =C2=A0 =C2=A0 controller is supported. There is initial support =
to allow the GICv2<br>
&gt;=C2=A0 =C2=A0 =C2=A0 to be supported in the future. Only pure Armv8.0 v=
irtualisation is<br>
&gt;=C2=A0 =C2=A0 =C2=A0 supported, the Virtualization Host Extensions are =
not currently used.<br>
&gt;=C2=A0 =C2=A0 =C2=A0 <br>
&gt;=C2=A0 =C2=A0 =C2=A0 With a separate userspace patch and U-Boot port Fr=
eeBSD guests are able<br>
&gt;=C2=A0 =C2=A0 =C2=A0 to boot to multiuser mode, and the hypervisor can =
be tested with the<br>
&gt;=C2=A0 =C2=A0 =C2=A0 kvm unit tests. Linux partially boots, but hangs b=
efore entering<br>
&gt;=C2=A0 =C2=A0 =C2=A0 userspace. Other operating systems are untested.<b=
r>
&gt;=C2=A0 =C2=A0 =C2=A0 <br>
&gt;=C2=A0 =C2=A0 =C2=A0 Sponsored by:=C2=A0 =C2=A0Arm Ltd<br>
&gt;=C2=A0 =C2=A0 =C2=A0 Sponsored by:=C2=A0 =C2=A0Innovate UK<br>
&gt;=C2=A0 =C2=A0 =C2=A0 Sponsored by:=C2=A0 =C2=A0The FreeBSD Foundation<b=
r>
&gt;=C2=A0 =C2=A0 =C2=A0 Sponsored by:=C2=A0 =C2=A0University Politehnica o=
f Bucharest<br>
&gt;=C2=A0 =C2=A0 =C2=A0 Differential Revision:=C2=A0 <a href=3D"https://re=
views.freebsd.org/D37428" rel=3D"noreferrer" target=3D"_blank">https://revi=
ews.freebsd.org/D37428</a><br>
<br>
FYI, sys/arm64/vmm/vmm.c shares a fair bit of code with sys/amd64/vmm/vmm.c=
<br>
and looks to be derived from the amd64 file, so I think it should preserve<=
br>
NetApp&#39;s copyright line in addition to Mihai&#39;s.<br></blockquote><di=
v><br></div><div>In general, the advice I&#39;ve been giving is that one sh=
ould retain copyrights when</div><div>there&#39;s at least 10%-20% remainin=
g of the original work. And one should hesitate to add</div><div>them unles=
s you&#39;ve contributed=C2=A010%-20% or more to the work (ideally more, bu=
t sometimes</div><div>that&#39;s gets squishy because the underlying law is=
 based on words like substantial</div><div>and de-minimus, which don&#39;t =
translate well to line counts, and for large works what</div><div>is substa=
ntial can be a bit subjective).</div><div><br></div><div>If they share so m=
uch, maybe we should also look at sharing directly, rather than by</div><di=
v>cut and paste in the future.</div><div><br></div><div>Warner</div></div><=
/div>

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