Re: [Qemu-devel] [PATCH] vmstate: Add VMSTATE_OPAQUE to save/load complex data structures

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

* rkir--- via Qemu-devel (qemu-devel@nongnu.org) wrote:
> From: Roman Kiryanov <rkir@google.com>
> 
> VMSTATE_OPAQUE allows passing user defined functions to save
> and load vmstate for cases when data structures do not fit
> into int/struct/array terms.
> 
> Signed-off-by: Roman Kiryanov <rkir@google.com>

Hi Roman,
  Thanks for the patch.

Can you give me an example of where you would use it?  I've been
trying to get rid as many of the open-coded cases as possible
and try and make sure vmstate can handle it.

Having said that;  would it be easier to pass the get/put functions
rather than the info ?

Dave

> ---
>  include/migration/vmstate.h | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> index 9224370ed5..2736daef17 100644
> --- a/include/migration/vmstate.h
> +++ b/include/migration/vmstate.h
> @@ -737,6 +737,19 @@ extern const VMStateInfo vmstate_info_qtailq;
>      .start        = offsetof(_type, _next),                              \
>  }
>  
> +/* Provides a way to save/load complex data structures that do not
> + * fit into int/struct/array terms.
> + * _info: a user defined instance of VMStateInfo to handle saving and loading.
> + */
> +#define VMSTATE_OPAQUE(_name, _version, _info) {                      \
> +    .name         = _name,                                            \
> +    .version_id   = (_version),                                       \
> +    .size         = 0,                                                \
> +    .info         = &(_info),                                         \
> +    .flags        = VMS_SINGLE,                                       \
> +    .offset       = 0,                                                \
> +}
> +
>  /* _f : field name
>     _f_n : num of elements field_name
>     _n : num of elements
> -- 
> 2.21.0.1020.gf2820cf01a-goog
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK