Re: [Qemu-devel] QEMU and Kconfig

[Eduardo Habkost <ehabkost@redhat.com>]

On Thu, Nov 08, 2018 at 06:58:11PM +0100, Paolo Bonzini wrote:
> On 08/11/2018 18:14, Eduardo Habkost wrote:
> > Keeping in mind that I might be talking about extra challenges we
> > won't address right now (no cart before the horse), I have new
> > questions:
> > 
> > Why you say backends are not a target configuration and
> > accelerators are?  What's the definition of "target
> > configuration"?
> 
> Something that affects the way

?

> 
> > Are we explicitly restricting the scope of this work to
> > enabling/disabling device emulation code right now?  Why?  Why
> > wouldn't we use kconfig to enable/disable simple backends with no
> > host dependency like SLIRP?
> 
> I think it would be more confusing if some backends were to use kconfig
> and some wouldn't.  We could certainly add something like
> 
> config VHOST_NET
>     depends on HOST_LINUX
>     default y
> 
> config SPICE
>     depends on HAVE_SPICE_SERVER
>     default Y
> 
> etc. but I think we agree it's more of a long term idea.

Agreed.

> 
> > Don't we want to make backends configurable per binary, too?
> > e.g.: I would expect the default configuration for a NEMU-like
> > binary to disable many backends.
> 
> Sure, we could do that.  However, right now you cannot have multiple
> binaries for a single target, so you couldn't have one single build
> include both a "full-blown" and a "reduced" x86 target.  Therefore,
> including e.g. SLIRP in qemu-system-arm but not in qemu-system-x86_64
> does not seem too interesting to me.  It would be different if you could
> build qemu-system-arm, qemu-system-x86_64, qemu-system-x86_64-lite, etc.

Understood.  I assumed this would be one of the short-term goals.
We can work on that later, then.


> 
> Paolo
> 
> > 
> >> It would surely be possible for configure to call into minikconf to
> >> parse a configuration file and apply dependencies (do we actually have
> >> dependencies across configure options?) or something like that, but
> >> let's not put the cart before the horse...
> > 
> > Agreed.
> > 
> 

-- 
Eduardo