Re: [PATCH] ioeventfd: Introduce KVM_IOEVENTFD_FLAG_PIPE

[Sasha Levin <levinsasha928@gmail.com>]

On Mon, 2011-07-04 at 17:45 +0300, Avi Kivity wrote:
> On 07/04/2011 05:38 PM, Sasha Levin wrote:
> > >
> > >  In general incremental development is great, but I don't want to
> > >  fragment the ABI.  I'd like to be able to forward an entire PCI BAR over
> > >  a pipe.  That means sending the address/data/length tuple, and both read
> > >  and write support.
> >
> > Would this mean that for sockets we want to remove the 8 byte limit?
> 
> Yes.  Register a range and support all sizes.
> 
> Perhaps it merits a separate ioctl.
> 
> > What about eventfds? We can remove the limit there and assume that if
> > the user asked for more than 8 bytes he knows what he's doing?
> 
> I can't really see that as useful.  eventfds destroy information; 
> without datamatch, you have no idea what value was written.  Even with 
> datamatch, you have no idea how many times it was written.  With a 
> range, you also have no idea which address was written.  It's pretty 
> meaningless.
> 

It is pretty useless, but I didn't want the ioctl to behave differently
when passing a socket or an eventfd.

If we do go for a new ioctl as you suggested then yes, problem solved.

-- 

Sasha.