Re: [PATCH 00/14] hw: define and enforce a standard lifecycle for versioned machines

["Cédric Le Goater" <clegoate@redhat.com>]

On 5/1/24 20:27, Daniel P. Berrangé wrote:
> Thomas proposed a new deprecation and removal policy for versioned
> machine types that would see them liable for deletion after 6 years:
> 
>    https://lists.nongnu.org/archive/html/qemu-devel/2024-04/msg04683.html
> 
> This suggest was met with broad approval, however, I suggested that we
> could take it further and actually mark them deprecated sooner, at the
> 3 year timeframe, and also fully automate the enablement of the runtime
> deprecation warning without developer intervention on every release
> cycle.
> 
> This series implements my suggestions.
> 
> The first patch introduces some helper macros and documents a standard
> code pattern for defining versioned machine types across targets.
> 
> The next 6 patches convert existing targets with versioned machine
> types (arm, s390x, ppc, m68k, i386) to use the new helper macros and
> code patterns.
> 
> A further patch introduces some helper macros for automating the
> handling of deprecation and deletion of versioned machine types.
> 
> Two more patches then enable the deprecation and deletion logic
> across all versioned machines
> 
> Finally we do some cleanup and document the new policy.
> 
> ........a tangent about VERSION file handling.......
> 
> One oddity here, is that during the development and release
> candidate phases the automatic logic in this series has an off-by-1
> error.
> 
> This is because when we, for example, add the "9.1" machine type
> versions, the VERSION file is still reporting '9.0.50', and then
> '9.0.9{1,2,3,4}'.
> 
> IOW, during development and in rc candidates, we fail to deprecate
> and delete 1 machine type. We should already have deprecated the
> 6.1 machine types, but the most recently deprecated is 6.0.
> This is pretty harmless since the final release does the right
> thing.
> 
> I wonder, however, whether we would benefit from changing how we
> update the VERSION file.
> 
> eg instead of re-using the micro digit to indicate a dev or rc
> snapshot, represent those explicitly. eg "9.1.0-dev" and
> "9.1.0-rc1", "9.1.0-rc2", etc in VERSION.
> 
> We don't use the full QEMU_VERSION in the code in all that many
> places. It appears in some help messages for command line tools,
> and in QMP query-version response, and in a few other misc places.
> At a glance it appears all of those places would easily handle a
> tagged version.
> 
> For release candidates in particular I think it would be saner
> to show the user the actual version the release is about to become,
> rather than the previous release's version. This would make the
> reported version match the rc tarball naming too which would be
> nice.
> 
> Anyway, this isn't a blocker for this machine type versioning
> proposal, just a thought....

I would agree with such a change. The version numbers always confused
me. AFAICT, only QEMU_VERSION_MICRO would need some massaging. It
shouldn't be too complex.

For the series,

Tested-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.



> 
> Daniel P. Berrangé (14):
>    include/hw: add helpers for defining versioned machine types
>    hw/arm: convert 'virt' machine definitions to use new macros
>    hw/s390x: convert 'ccw' machine definitions to use new macros
>    hw/ppc: convert 'spapr' machine definitions to use new macros
>    hw/m68k: convert 'virt' machine definitions to use new macros
>    hw/i386: convert 'i440fx' machine definitions to use new macros
>    hw/i386: convert 'q35' machine definitions to use new macros
>    include/hw: add macros for deprecation & removal of versioned machines
>    hw: temporarily disable deletion of versioned machine types
>    hw: set deprecation info for all versioned machine types
>    hw: skip registration of outdated versioned machine types
>    hw/ppc: remove obsolete manual deprecation reason string of spapr
>      machines
>    hw/i386: remove obsolete manual deprecation reason string of i440fx
>      machines
>    docs: document special exception for machine type deprecation &
>      removal
> 
>   docs/about/deprecated.rst  |  12 ++
>   hw/arm/virt.c              |  30 +++--
>   hw/i386/pc_piix.c          | 252 +++++++++++++++-------------------
>   hw/i386/pc_q35.c           | 215 +++++++++++++----------------
>   hw/m68k/virt.c             |  53 +++++---
>   hw/ppc/spapr.c             |  96 +++++++------
>   hw/s390x/s390-virtio-ccw.c |  98 ++++++++------
>   include/hw/boards.h        | 268 +++++++++++++++++++++++++++++++++++++
>   include/hw/i386/pc.h       |  32 +++++
>   9 files changed, 666 insertions(+), 390 deletions(-)
>