Can't build in the virtio console driver on x86_64 when the other virtio drivers are modular

Can't build in the virtio console driver on x86_64 when the other virtio drivers are modular

[Chuck Ebbert]

The virtio configuration options are inconsistent. According to this,
every options that needs virtio will select it:

 # Virtio always gets selected by whoever wants it.
 config VIRTIO
        tristate

Note that it's not user-selectable, so any config file that tries to
set it will be ignored when kconfig loads those options. And yet we
have a whole set of options that depend on VIRTIO, like VIRTIO_CONSOLE
for example. This makes it impossible to have VIRTIO_PCI modular and
VIRTIO_CONSOLE built-in on x86_64, because:

1. VIRTIO_PCI selects VIRTIO and sets it to M
2. VIRTIO_CONSOLE gets forced to M because one of its dependencies is M

So either VIRTIO (and VIRTIO_RING) need to be user-selectable, or all
of the options that depend on VIRTIO need to be changed to select it
instead.

(For even more fun, LGUEST_GUEST on i386 forces VIRTIO, VIRTIO_RING and
VIRTIO_CONSOLE all to Y.)

Re: Can't build in the virtio console driver on x86_64 when the other virtio drivers are modular

[Amit Shah]

On (Thu) 24 Feb 2011 [11:28:19], Chuck Ebbert wrote:
> The virtio configuration options are inconsistent. According to this,
> every options that needs virtio will select it:
> 
>  # Virtio always gets selected by whoever wants it.
>  config VIRTIO
>         tristate
> 
> Note that it's not user-selectable, so any config file that tries to
> set it will be ignored when kconfig loads those options. And yet we
> have a whole set of options that depend on VIRTIO, like VIRTIO_CONSOLE
> for example. This makes it impossible to have VIRTIO_PCI modular and
> VIRTIO_CONSOLE built-in on x86_64, because:

Any reason to have VIRTIO_PCI modular instead of built in (on x86-64,
virtio-console won't work without virtio-pci anyway)?

		Amit

Re: Can't build in the virtio console driver on x86_64 when the other virtio drivers are modular

[Chuck Ebbert]

On Fri, 25 Feb 2011 11:38:15 +0530
Amit Shah <amit.shah@redhat.com> wrote:

> On (Thu) 24 Feb 2011 [11:28:19], Chuck Ebbert wrote:
> > The virtio configuration options are inconsistent. According to this,
> > every options that needs virtio will select it:
> > 
> >  # Virtio always gets selected by whoever wants it.
> >  config VIRTIO
> >         tristate
> > 
> > Note that it's not user-selectable, so any config file that tries to
> > set it will be ignored when kconfig loads those options. And yet we
> > have a whole set of options that depend on VIRTIO, like VIRTIO_CONSOLE
> > for example. This makes it impossible to have VIRTIO_PCI modular and
> > VIRTIO_CONSOLE built-in on x86_64, because:
> 
> Any reason to have VIRTIO_PCI modular instead of built in (on x86-64,
> virtio-console won't work without virtio-pci anyway)?
> 

None that I know of offhand, other than not building in things unless
absolutely necessary. There's no dependency of any kind there, so it's
even possible to build a kernel with VIRTIO_CONSOLE enabled and
VIRTIO_PCI completely disabled.

Re: Can't build in the virtio console driver on x86_64 when the other virtio drivers are modular

[Amit Shah]

On (Fri) 25 Feb 2011 [12:13:20], Chuck Ebbert wrote:
> On Fri, 25 Feb 2011 11:38:15 +0530
> Amit Shah <amit.shah@redhat.com> wrote:
> 
> > On (Thu) 24 Feb 2011 [11:28:19], Chuck Ebbert wrote:
> > > The virtio configuration options are inconsistent. According to this,
> > > every options that needs virtio will select it:
> > > 
> > >  # Virtio always gets selected by whoever wants it.
> > >  config VIRTIO
> > >         tristate
> > > 
> > > Note that it's not user-selectable, so any config file that tries to
> > > set it will be ignored when kconfig loads those options. And yet we
> > > have a whole set of options that depend on VIRTIO, like VIRTIO_CONSOLE
> > > for example. This makes it impossible to have VIRTIO_PCI modular and
> > > VIRTIO_CONSOLE built-in on x86_64, because:
> > 
> > Any reason to have VIRTIO_PCI modular instead of built in (on x86-64,
> > virtio-console won't work without virtio-pci anyway)?
> > 
> 
> None that I know of offhand, other than not building in things unless
> absolutely necessary. There's no dependency of any kind there, so it's
> even possible to build a kernel with VIRTIO_CONSOLE enabled and
> VIRTIO_PCI completely disabled.

Yes, that's that way because not all architectures need virtio-pci to
have virtio-console functional (eg. s390, which doesn't have a PCI
bus).

So if you're only interested in the x86-64 arch, you could compile in
virtio-pci and virtio-console and this should happily work.

		Amit