Re: [PATCH] migration: Remove load_state_old and minimum_version_id_old

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Maydell (peter.maydell@linaro.org) wrote:
> There are no longer any VMStateDescription structs in the tree which
> use the load_state_old support for custom handling of incoming
> migration from very old QEMU.  Remove the mechanism entirely.
> 
> This includes removing one stray useless setting of
> minimum_version_id_old in a VMStateDescription with no load_state_old
> function, which crept in after the global weeding-out of them in
> commit 17e313406126.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Thanks!

> ---
>  docs/devel/migration.rst    | 10 ++--------
>  include/migration/vmstate.h |  2 --
>  hw/ssi/xlnx-versal-ospi.c   |  1 -
>  migration/vmstate.c         |  6 ------
>  4 files changed, 2 insertions(+), 17 deletions(-)
> 
> diff --git a/docs/devel/migration.rst b/docs/devel/migration.rst
> index 24012534827..3e9656d8e0b 100644
> --- a/docs/devel/migration.rst
> +++ b/docs/devel/migration.rst
> @@ -389,19 +389,13 @@ Each version is associated with a series of fields saved.  The ``save_state`` al
>  the state as the newer version.  But ``load_state`` sometimes is able to
>  load state from an older version.
>  
> -You can see that there are several version fields:
> +You can see that there are two version fields:
>  
>  - ``version_id``: the maximum version_id supported by VMState for that device.
>  - ``minimum_version_id``: the minimum version_id that VMState is able to understand
>    for that device.
> -- ``minimum_version_id_old``: For devices that were not able to port to vmstate, we can
> -  assign a function that knows how to read this old state. This field is
> -  ignored if there is no ``load_state_old`` handler.
>  
> -VMState is able to read versions from minimum_version_id to
> -version_id.  And the function ``load_state_old()`` (if present) is able to
> -load state from minimum_version_id_old to minimum_version_id.  This
> -function is deprecated and will be removed when no more users are left.
> +VMState is able to read versions from minimum_version_id to version_id.
>  
>  There are *_V* forms of many ``VMSTATE_`` macros to load fields for version dependent fields,
>  e.g.
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index 017c03675ca..ad24aa19345 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -181,9 +181,7 @@ struct VMStateDescription {
>      int unmigratable;
>      int version_id;
>      int minimum_version_id;
> -    int minimum_version_id_old;
>      MigrationPriority priority;
> -    LoadStateHandler *load_state_old;
>      int (*pre_load)(void *opaque);
>      int (*post_load)(void *opaque, int version_id);
>      int (*pre_save)(void *opaque);
> diff --git a/hw/ssi/xlnx-versal-ospi.c b/hw/ssi/xlnx-versal-ospi.c
> index 7ecd148fdf3..c762e0b3679 100644
> --- a/hw/ssi/xlnx-versal-ospi.c
> +++ b/hw/ssi/xlnx-versal-ospi.c
> @@ -1800,7 +1800,6 @@ static const VMStateDescription vmstate_xlnx_versal_ospi = {
>      .name = TYPE_XILINX_VERSAL_OSPI,
>      .version_id = 1,
>      .minimum_version_id = 1,
> -    .minimum_version_id_old = 1,
>      .fields = (VMStateField[]) {
>          VMSTATE_FIFO8(rx_fifo, XlnxVersalOspi),
>          VMSTATE_FIFO8(tx_fifo, XlnxVersalOspi),
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index 05f87cdddc5..36ae8b9e191 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -90,12 +90,6 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
>          return -EINVAL;
>      }
>      if  (version_id < vmsd->minimum_version_id) {
> -        if (vmsd->load_state_old &&
> -            version_id >= vmsd->minimum_version_id_old) {
> -            ret = vmsd->load_state_old(f, opaque, version_id);
> -            trace_vmstate_load_state_end(vmsd->name, "old path", ret);
> -            return ret;
> -        }
>          error_report("%s: incoming version_id %d is too old "
>                       "for local minimum version_id  %d",
>                       vmsd->name, version_id, vmsd->minimum_version_id);
> -- 
> 2.25.1
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK