Re: [PATCH v2 1/5] Revert "include/hw: temporarily disable deletion of versioned machine types"

[Thomas Huth <thuth@redhat.com>]

On 29/04/2025 15.15, Daniel P. Berrangé wrote:
> This reverts commit c9fd2d9a48ee3c195cf83cc611b87b09f02f0013.
> 
> When we introduced the specialized machine type deprecation policy, we
> allow automatic deprecation to take effect immediately, but blocked the
> automatic deletion of machine types for 2 releases. This ensured we
> complied with the historical deprecation policy during the transition
> window. Startnig with the 10.1.0 dev cycle, the old machine types would

typo: Startnig

> be candidates for removal under both the old and new deprecation
> policies.
> 
> Thus we can now enable automatic deletion of old machine types, which
> takes effect by skipping the QOM type registration. This prevents the
> machine types being listed with '-machine help', and blocks their
> creation. The actual code can be purged at a convenient time of the
> maintainer's choosing.
> 
> In the case of the x86_64 target, this change results in the blocking
> of the following machine types:
> 
>    pc-i440fx-4.0        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-3.1        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-3.0        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.9        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.8        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.7        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.6        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.5        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.4        Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.12       Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.11       Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-i440fx-2.10       Standard PC (i440FX + PIIX, 1996) (deprecated)
>    pc-q35-4.0.1         Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-4.0           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-3.1           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-3.0           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.9           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.8           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.7           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.6           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.5           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.4           Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.12          Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.11          Standard PC (Q35 + ICH9, 2009) (deprecated)
>    pc-q35-2.10          Standard PC (Q35 + ICH9, 2009) (deprecated)
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>   include/hw/boards.h | 19 +------------------
>   1 file changed, 1 insertion(+), 18 deletions(-)
> 
> diff --git a/include/hw/boards.h b/include/hw/boards.h
> index 765dc8dd35..74a8e96b2e 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -719,28 +719,11 @@ struct MachineState {
>    * suitable period of time has passed, it will cause
>    * execution of the method to return, avoiding registration
>    * of the machine
> - *
> - * The new deprecation and deletion policy for versioned
> - * machine types was introduced in QEMU 9.1.0.
> - *
> - * Under the new policy a number of old machine types (any
> - * prior to 2.12) would be liable for immediate deletion
> - * which would be a violation of our historical deprecation
> - * and removal policy
> - *
> - * Thus deletions are temporarily gated on existance of
> - * the env variable "QEMU_DELETE_MACHINES" / QEMU version
> - * number >= 10.1.0. This gate can be deleted in the 10.1.0
> - * dev cycle
>    */
>   #define MACHINE_VER_DELETION(...) \
>       do { \
>           if (MACHINE_VER_SHOULD_DELETE(__VA_ARGS__)) { \
> -            if (getenv("QEMU_DELETE_MACHINES") || \
> -                QEMU_VERSION_MAJOR > 10 || (QEMU_VERSION_MAJOR == 10 && \
> -                                            QEMU_VERSION_MINOR >= 1)) { \
> -                return; \
> -            } \
> +            return; \

I wonder whether we might want to have it the other way round now instead, 
so that we could re-activate the dead machines in case a certain environment 
variable (QEMU_ZOMBI_MACHINES) is set? Anyway, just an idea, not sure 
whether it's a good one. So for this patch:

Reviewed-by: Thomas Huth <thuth@redhat.com>


>           } \
>       } while (0)
>