Re: [Qemu-devel] [PATCH v3 06/22] memory-device: document MemoryDeviceClass

[Igor Mammedov]

On Mon, 24 Sep 2018 14:40:24 +0200
David Hildenbrand <address@hidden> wrote:

> On 24/09/2018 14:39, Igor Mammedov wrote:
> > On Mon, 24 Sep 2018 14:26:23 +0200
> > David Hildenbrand <address@hidden> wrote:
> >   
> >> On 24/09/2018 14:22, Igor Mammedov wrote:  
> >>> On Thu, 20 Sep 2018 12:32:27 +0200
> >>> David Hildenbrand <address@hidden> wrote:
> >>>     
> >>>> Document the functions and when to not expect errors.
> >>>>
> >>>> Signed-off-by: David Hildenbrand <address@hidden>
> >>>> ---
> >>>>  include/hw/mem/memory-device.h | 13 +++++++++++++
> >>>>  1 file changed, 13 insertions(+)
> >>>>
> >>>> diff --git a/include/hw/mem/memory-device.h 
> >>>> b/include/hw/mem/memory-device.h    
> >>> [...]
> >>>     
> >>>> + * @get_plugged_size: The amount of memory provided by this @md 
> >>>> currently
> >>>> + * usable ("plugged") by the guest.
> >>>> + * @get_region_size: The size of the memory region of the @md that's 
> >>>> mapped
> >>>> + * in guest physical memory at @get_addr    
> >>> Tried to read it several times,
> >>> but still description of hooks makes them look like they are doing the 
> >>> same thing,
> >>> so what's the difference?    
> >>
> >> That's a preparation mainly for virtio-mem, where we manage the amount
> >> of memory that is actually accessible and visible by the guest (plugged)
> >> inside a memory region dynamically. The difference exists purely for
> >> stats. (could have been introduced later, but it made sense to split
> >> this off right when factoring this stuff out into memory-device code).  
> > Purpose might be obvious (for you) right now, but later when reader
> > would be reading history it's confusing.
> > I'd postpone it until there is an actual user for it.
> >   
> 
> What to postpone? The doc update? get_plugged_size is already upstream.
We can't do anything to merged stuff (unless one would remove it :/),
but doc update as is, just adding more confusion.

Alternatively clarify distinction referring to future devices that
might return different values for both hooks.