Re: git: 47e073941f4e - main - Import the kernel parts of bhyve/arm64

On Thu, Feb 22, 2024 at 11:30 AM John Baldwin <jhb@freebsd.org> wrote:

> 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=47e073941f4e7ca6e9bde3fa65abbfcfed6bfa2b
> >
> > 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 GICv2
> >      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 the
> >      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 preserve
> 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