Re: [RFC PATCH 0/5] Removing support for 32bit KVM/arm host

From: Olof Johansson <olof@lixom.net>
To: Marc Zyngier <maz@kernel.org>
Cc: Anders Berg <anders.berg@lsi.com>,
	Russell King <linux@arm.linux.org.uk>,
	Arnd Bergmann <arnd@arndb.de>,
	kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
	Will Deacon <will@kernel.org>,
	kvmarm@lists.cs.columbia.edu,
	Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 0/5] Removing support for 32bit KVM/arm host
Date: Mon, 10 Feb 2020 16:21:42 +0100	[thread overview]
Message-ID: <CAOesGMhHkez-5vxwWuzXc2Rm=dYYWjMX9C8AewVy9GDWuZcwMw@mail.gmail.com> (raw)
In-Reply-To: <20200210141324.21090-1-maz@kernel.org>

On Mon, Feb 10, 2020 at 3:13 PM Marc Zyngier <maz@kernel.org> wrote:
>
> KVM/arm was merged just over 7 years ago, and has lived a very quiet
> life so far. It mostly works if you're prepared to deal with its
> limitations, it has been a good prototype for the arm64 version,
> but it suffers a few problems:
>
> - It is incomplete (no debug support, no PMU)
> - It hasn't followed any of the architectural evolutions
> - It has zero users (I don't count myself here)
> - It is more and more getting in the way of new arm64 developments
>
> So here it is: unless someone screams and shows that they rely on
> KVM/arm to be maintained upsteam, I'll remove 32bit host support
> form the tree. One of the reasons that makes me confident nobody is
> using it is that I never receive *any* bug report. Yes, it is perfect.
> But if you depend on KVM/arm being available in mainline, please shout.
>
> To reiterate: 32bit guest support for arm64 stays, of course. Only
> 32bit host goes. Once this is merged, I plan to move virt/kvm/arm to
> arm64, and cleanup all the now unnecessary abstractions.
>
> The patches have been generated with the -D option to avoid spamming
> everyone with huge diffs, and there is a kvm-arm/goodbye branch in
> my kernel.org repository.
>
> Marc Zyngier (5):
>   arm: Unplug KVM from the build system
>   arm: Remove KVM from config files
>   arm: Remove 32bit KVM host support
>   arm: Remove HYP/Stage-2 page-table support
>   arm: Remove GICv3 vgic compatibility macros

Since I'm generally happy to drop legacy code that has no users, with
the "if there are any significant users that speak up, I'll revoke my
support" caveat:

Acked-by: Olof Johansson <olof@lixom.net>


-Olof
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