Re: [Qemu-devel] [RFC 2/5] virtio: add child alias properties for virtio-blk

[Peter Crosthwaite]

On Wed, May 14, 2014 at 2:33 PM, Stefan Hajnoczi <address@hidden> wrote:
> On Wed, May 14, 2014 at 02:04:25PM +0000, Peter Crosthwaite wrote:
>> On Wed, Mar 19, 2014 at 3:48 PM, Stefan Hajnoczi <address@hidden> wrote:
>> > Now that qdev child alias properties exist, define aliases for
>> > virtio-blk properties.  The aliases will replace the duplicated
>> > properties that current live in virtio-blk-pci, virtio-blk-ccw, and
>> > friends.
>> >
>> > Signed-off-by: Stefan Hajnoczi <address@hidden>
>> > ---
>> >  include/hw/block/block.h       | 14 ++++++++++++++
>> >  include/hw/virtio/virtio-blk.h | 17 +++++++++++++++++
>> >  2 files changed, 31 insertions(+)
>> >
>> > diff --git a/include/hw/block/block.h b/include/hw/block/block.h
>> > index 7c3d6c8..702f1eb 100644
>> > --- a/include/hw/block/block.h
>> > +++ b/include/hw/block/block.h
>> > @@ -52,11 +52,25 @@ static inline unsigned int 
>> > get_physical_block_exp(BlockConf *conf)
>> >      DEFINE_PROP_UINT32("discard_granularity", _state, \
>> >                         _conf.discard_granularity, -1)
>> >
>> > +#define DEFINE_BLOCK_CHILD_ALIASES(_state, _field)                      \
>> > +    DEFINE_PROP_CHILD_ALIAS("drive", _state, _field),                   \
>> > +    DEFINE_PROP_CHILD_ALIAS("logical_block_size", _state, _field),      \
>> > +    DEFINE_PROP_CHILD_ALIAS("physical_block_size", _state, _field),     \
>> > +    DEFINE_PROP_CHILD_ALIAS("min_io_size", _state, _field),             \
>> > +    DEFINE_PROP_CHILD_ALIAS("opt_io_size", _state, _field),             \
>> > +    DEFINE_PROP_CHILD_ALIAS("bootindex", _state, _field),               \
>> > +    DEFINE_PROP_CHILD_ALIAS("discard_granularity", _state, _field)
>> > +
>> >  #define DEFINE_BLOCK_CHS_PROPERTIES(_state, _conf)      \
>> >      DEFINE_PROP_UINT32("cyls", _state, _conf.cyls, 0),  \
>> >      DEFINE_PROP_UINT32("heads", _state, _conf.heads, 0), \
>> >      DEFINE_PROP_UINT32("secs", _state, _conf.secs, 0)
>> >
>> > +#define DEFINE_BLOCK_CHS_CHILD_ALIASES(_state, _field)      \
>> > +    DEFINE_PROP_CHILD_ALIAS("cyls", _state, _field),        \
>> > +    DEFINE_PROP_CHILD_ALIAS("heads", _state, _field),       \
>> > +    DEFINE_PROP_CHILD_ALIAS("secs", _state, _field)
>> > +
>> >  /* Configuration helpers */
>> >
>> >  void blkconf_serial(BlockConf *conf, char **serial);
>> > diff --git a/include/hw/virtio/virtio-blk.h 
>> > b/include/hw/virtio/virtio-blk.h
>> > index e4c41ff..5095ff4 100644
>> > --- a/include/hw/virtio/virtio-blk.h
>> > +++ b/include/hw/virtio/virtio-blk.h
>> > @@ -153,6 +153,23 @@ typedef struct VirtIOBlock {
>> >          DEFINE_PROP_IOTHREAD("x-iothread", _state, _field.iothread)
>> >  #endif /* __linux__ */
>> >
>> > +#ifdef __linux__
>> > +#define DEFINE_VIRTIO_BLK_CHILD_ALIASES(_state, _field)                   
>> >     \
>> > +        DEFINE_BLOCK_CHILD_ALIASES(_state, _field),                       
>> >     \
>> > +        DEFINE_BLOCK_CHS_CHILD_ALIASES(_state, _field),                   
>> >     \
>> > +        DEFINE_PROP_CHILD_ALIAS("serial", _state, _field),                
>> >     \
>> > +        DEFINE_PROP_CHILD_ALIAS("config-wce", _state, _field),            
>> >     \
>> > +        DEFINE_PROP_CHILD_ALIAS("scsi", _state, _field),                  
>> >     \
>> > +        DEFINE_PROP_CHILD_ALIAS("x-iothread", _state, _field)
>> > +#else
>> > +#define DEFINE_VIRTIO_BLK_CHILD_ALIASES(_state, _field)                   
>> >     \
>> > +        DEFINE_BLOCK_CHILD_ALIASES(_state, _field),                       
>> >     \
>> > +        DEFINE_BLOCK_CHS_CHILD_ALIASES(_state, _field),                   
>> >     \
>> > +        DEFINE_PROP_CHILD_ALIAS("serial", _state, _field),                
>> >     \
>> > +        DEFINE_PROP_CHILD_ALIAS("config-wce", _state, _field),            
>> >     \
>> > +        DEFINE_PROP_CHILD_ALIAS("x-iothread", _state, _field)
>> > +#endif /* __linux__ */
>>
>> Can the duplication be avoided with:
>>
>> #ifdef __linux__
>> #define DEFINE_VIRTIO_BLK_CHILD_ALIASES_LINUX \
>>         DEFINE_PROP_CHILD_ALIAS("scsi", _state, _field),
>> #else
>> #define DEFINE_VIRTIO_BLK_CHILD_ALIASES_LINUX
>> #endif
>>
>> ?
>
> Absolutely, but I want each patch to do only one thing.
>
> The "duplication" I referred to in the commit description is something
> else: for virtio we create two sets of qdev properties with the same
> name.  The first set is in the parent object and the second set is in
> the child.  The actual implementation of this in hw/virtio/virtio-pci.c
> varies between device types: in some cases we really have the property
> values duplicated, in other cases we share the memory between parent and
> child.  It's nuts and I want to eliminate that.
>

Right, just overload of the term "duplication". I was only reffering
to the duplicated text in your added code, not the function of the
patch. Sorry about confusion.

Regards,
Peter

> The __linux__ ifdef duplication is a minor thing that doesn't worry me.
> It could be fixed in a trivial patch.
>
> Stefan
>