Re: [RFC PATCH 0/3] generic hypercall support

[Avi Kivity]

Gregory Haskins wrote:
> Chris Wright wrote:
>   
> > * Gregory Haskins (ghaskins@xxxxxxxxxx) wrote:
> >   
> >     
> > > Chris Wright wrote:
> > >     
> > >       
> > > > But a free-form hypercall(unsigned long nr, unsigned long *args, size_t count)
> > > > means hypercall number and arg list must be the same in order for code
> > > > to call hypercall() in a hypervisor agnostic way.
> > > >       
> > > >         
> > > Yes, and that is exactly the intention.  I think its perhaps the point
> > > you are missing.
> > >     
> > >       
> > Yes, I was reading this as purely any hypercall, but it seems a bit
> > more like:
> >  pv_io_ops->iomap()
> >  pv_io_ops->ioread()
> >  pv_io_ops->iowrite()
> >   
> >     
>
> Right.
>   

Hmm, reminds me of something I thought of a while back.

We could implement an 'mmio hypercall' that does mmio reads/writes via a 
hypercall instead of an mmio operation.  That will speed up mmio for 
emulated devices (say, e1000).  It's easy to hook into Linux 
(readl/writel), is pci-friendly, non-x86 friendly, etc.

It also makes the device work when hypercall support is not available 
(qemu/tcg); you simply fall back on mmio.

--
error compiling committee.c: too many arguments to function

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