Re: [for-5.0] Deprecate KVM support for AArch32

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Apr 14, 2020 at 01:09:35PM +0100, Peter Maydell wrote:
> The Linux kernel has dropped support for allowing 32-bit Arm systems
> to host KVM guests (kernel commit 541ad0150ca4aa663a2, which just
> landed upstream in the 5.7 merge window).  Mark QEMU's support for
> this configuration as deprecated, so that we can delete that support
> code in 5.2.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> I was reading the 5.7 merge window writeup on LWN this weekend
> and saw that the dropping of 32-bit support had gone in; just
> enough time to squeeze our deprecation warning into 5.0 so we
> can drop the code in 5.2 rather than 6.0...
> 
>  docs/system/deprecated.rst | 8 ++++++++
>  1 file changed, 8 insertions(+)

The docs are sufficient to start the deprecation process, but
we might consider also having a warning from configure, or a
message on stderr at runtime to make it more visible to users.

> 
> diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
> index c633fe2beff..3142fac3865 100644
> --- a/docs/system/deprecated.rst
> +++ b/docs/system/deprecated.rst
> @@ -336,6 +336,14 @@ The ``compat`` property used to set backwards compatibility modes for
>  the processor has been deprecated. The ``max-cpu-compat`` property of
>  the ``pseries`` machine type should be used instead.
>  
> +KVM guest support on 32-bit Arm hosts (since 5.0)
> +'''''''''''''''''''''''''''''''''''''''''''''''''
> +
> +The Linux kernel has dropped support for allowing 32-bit Arm systems
> +to host KVM guests as of the 5.7 kernel. Accordingly, QEMU is deprecating
> +its support for this configuration and will remove it in a future version.
> +Running 32-bit guests on a 64-bit Arm host remains supported.
> +

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


Regards,
Daniel
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