Re: [PATCH v2] block: Remove unused BlockDeviceMapEntry

[Max Reitz]

On 30.10.20 07:24, Markus Armbruster wrote:
> BlockDeviceMapEntry has never been used.  It was added in commit
> facd6e2 "so that it is published through the introspection mechanism."
> What exactly introspecting types that aren't used for anything could
> accomplish isn't clear.  What "introspection mechanism" to use is also
> nebulous.  To the best of my knowledge, there has never been one that
> covered this type.  Certainly not query-qmp-schema, which includes
> only types that are actually used in QMP.
> 
> Not being able to introspect BlockDeviceMapEntry hasn't bothered
> anyone enough to complain in almost four years.  Get rid of it.
> 
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Eric Blake <eblake@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
> I found an old patch I neglected to merge.
> 
> Max replied to a remark in Eric's review of v1:
> 
>     Max Reitz <mreitz@redhat.com> writes:
> 
>     > On 2017-07-28 20:10, Eric Blake wrote:
>     >> This type is the schema for 'qemu-img map --output=json'.  And I had a
>     >> patch once (that I need to revive) that added a JSON Output visitor; at
>     >> which point I fixed qemu-img to convert from QAPI to JSON instead of
>     >> open-coding its construction of its output string, at which point the
>     >> QAPI generated code for this type is useful.
>     > (Very late reply, I know, I just stumbled over *MapEntry when looking
>     > over block-core.json what we might want to deprecate in 3.0)
>     >
>     > We already use MapEntry there -- why don't we output just that instead?
>     > The only difference seems to be an additional @filename parameter which
>     > would probably be actually nice to include in the output.
>     >
>     > Except that BlockDeviceMapEntry's documentation is better, so we should
>     > merge that into MapEntry before removing the former.
>     >
>     > Max
> 
> https://lists.nongnu.org/archive/html/qemu-devel/2017-12/msg02933.html
> 
> Me doing the doc update Max suggested could take more than one
> iteration, as I know nothing about this stuff.  Max, could you give it
> a try?  Feel free to take over my patch.

Thanks, done :)

https://lists.nongnu.org/archive/html/qemu-block/2020-11/msg00143.html

Max