Re: [Qemu-devel] [PATCH v3 4/5] Enable fw_cfg DMA interface for ARM

[Gerd Hoffmann]

  Hi,

> > My hypothesis (which I guess I'm volunteering to verify, unless we
> > end up rejecting this immediately as a bad idea, for some reason that
> > I have missed), is that current functionality wouldn't change, given
> > the way existing callbacks work right now, and that we could run the
> > callback each time a blob is *selected*, rather than hooking into the
> > (dma/mmio/pio) read methods.
> 
> Callback executed on first read only sounds okay to me, callback
> executed on selection... hm... don't like it. :)

Care to explain why?

I think callback on selection would be better.  Interface is more clear
then, I don't like read having different behavior depending on hidden
state (current offset).  And in practice selection and read will always
be called together, so there shouldn't be a difference in practice ...

cheers,
  Gerd