[Qemu-devel] Re: [PATCH 0/4][RFC] Add module infrastructure to QEMU

[Anthony Liguori]

Paul Brook wrote:
> On Monday 11 May 2009, Anthony Liguori wrote:
>   
> > The numeric priorities are an implementation detail.  No one should ever
> > consume module_init() directly and I should add appropriately scary
> > comments to that affect.
> >     
>
> Having looked a bit deeper, you're not actually implementing priorities. 
> You're implementing different categories of init function. So this should be 
> an enum, and be renames to something less confusing.
>   

Good point, will do.

> > We do have dependencies.  I'd like virtio to be a module, and I'd like
> > virtio-net, virtio-blk, etc. to be modules.  This gets exposed as
> > virtio.c being a bus_init() and virtio-*.c being virtio_init().  We use
> > the integer priorities in module.h to express this.
> >     
>
> I'm not convinced virtio is as much of a separate entity as you think it is. 
> It's certainly not a bus. It's an implementation detail that happens to be 
> shared by several devices.
>   

It is once you abstract out the transport API from the transport 
implementation.  We fall short here in QEMU today mainly for better 
integration with how machines are created today.  I'd like to refactor 
the QEMU virtio code though to be closer to the Linux side of things.  I 
see a module mechanism like this as a prereq for doing such a refactoring.

s390 uses a different transport implementation (there is no PCI on 
s390)for virtio so if QEMU ever were to support KVM with s390, we would 
need a way to support this.

> Paul
>   


--
Regards,

Anthony Liguori