Re: [Qemu-devel] [PATCH v5 1/2 (for 2.10)] docs: document support lifetime for features

[Paolo Bonzini]

On 19/07/2017 13:56, Thomas Huth wrote:
> address@hidden Machine types
> address@hidden Machine types
> +
> +For architectures which aim to support live migration compatibility
> +across releases, each release will introduce a new versioned machine
> +type. For example, the 2.8.0 release introduced machine types
> +``pc-i440fx-2.8'' and ``pc-q35-2.8'' for the x86_64/i686 architectures.
> +
> +To allow live migration of a guest running on a 2.8.0 release to a
> +2.9.0, the QEMU 2.9.0 version must support the ``pc-i440fx-2.8'' and
> +``pc-q35-2.8''. To allow users live migrating VMs to skip multiple
> +intermediate releases when upgrading, new releases of QEMU will
> +support machine types from many previous versions.
> +
> +The supported lifetime for versioned machine types is 12 releases,
> +which is equivalent to 4 years worth of previous QEMU releases.

I think there's still no consensus on this.  The first two paragraphs
should be added to the documentation for -machine in qemu-options.hx,
since "-machine [type=]foo" is currently not documented at all.

Paolo