xen kconfig: clarify INPUT_XEN_KBDDEV_FRONTEND select

Commit Message

Stefano Stabellini Feb. 16, 2016, 12:14 p.m. UTC

On Tue, 16 Feb 2016, Arnd Bergmann wrote:
> On Monday 15 February 2016 16:51:08 Stefano Stabellini wrote:
> > > 
> > > diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> > > index 8ea45a5cd806..fd3d6fd290a9 100644
> > > --- a/drivers/video/fbdev/Kconfig
> > > +++ b/drivers/video/fbdev/Kconfig
> > > @@ -2241,6 +2241,7 @@ config FB_VIRTUAL
> > >  config XEN_FBDEV_FRONTEND
> > >       tristate "Xen virtual frame buffer support"
> > >       depends on FB && XEN
> > > +     depends on INPUT || !INPUT_MISC
> > >       select FB_SYS_FILLRECT
> > >       select FB_SYS_COPYAREA
> > >       select FB_SYS_IMAGEBLIT
> > 
> > This looks very hackish. Couldn't we just do the following?
> > 
> > diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
> > index 8ea45a5..3c15f6d 100644
> > --- a/drivers/video/fbdev/Kconfig
> > +++ b/drivers/video/fbdev/Kconfig
> > @@ -2246,7 +2246,7 @@ config XEN_FBDEV_FRONTEND
> >         select FB_SYS_IMAGEBLIT
> >         select FB_SYS_FOPS
> >         select FB_DEFERRED_IO
> > -       select INPUT_XEN_KBDDEV_FRONTEND if INPUT_MISC
> > +       select INPUT_XEN_KBDDEV_FRONTEND if (INPUT && INPUT_MISC)
> >         select XEN_XENBUS_FRONTEND
> >         default y
> >         help
> > 
> 
> No, that doesn't solve the problem:
> 
> If XEN_FBDEV_FRONTEND=y, INPUT=m and INPUT_MISC=y, we would still
> get INPUT_XEN_KBDDEV_FRONTEND=y, which cannot work because of INPUT=m.
> 
> INPUT_MISC already depends on INPUT, so your change has no effect
> at all.

Please correct me if I am wrong, but the difference is that with this
change if INPUT=m, then the build system would ask the user whether she
wants to select INPUT_XEN_KBDDEV_FRONTEND as m or y, instead of
unconditionally set INPUT_XEN_KBDDEV_FRONTEND=y.

However it is true that if the users chooses
INPUT_XEN_KBDDEV_FRONTEND=y, then the problem persists.
Maybe we also need:



Do you have a kernel config with INPUT=m that I can use to test with?

Comments

Arnd Bergmann Feb. 16, 2016, 3:05 p.m. UTC | #1

On Tuesday 16 February 2016 12:14:14 Stefano Stabellini wrote:
> > at all.
> 
> Please correct me if I am wrong, but the difference is that with this
> change if INPUT=m, then the build system would ask the user whether she
> wants to select INPUT_XEN_KBDDEV_FRONTEND as m or y, instead of
> unconditionally set INPUT_XEN_KBDDEV_FRONTEND=y.

INPUT_XEN_KBDDEV_FRONTEND cannot be set by the user to 'y' if
INPUT=m, because of an implied dependency around the input/misc/Kconfig
file.

> However it is true that if the users chooses
> INPUT_XEN_KBDDEV_FRONTEND=y, then the problem persists.
> Maybe we also need:
> 
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 1f2337a..303df24 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -721,7 +721,7 @@ config INPUT_CMA3000_I2C
>  
>  config INPUT_XEN_KBDDEV_FRONTEND
>         tristate "Xen virtual keyboard and mouse support"
> -       depends on XEN
> +       depends on XEN && INPUT
>         default y
>         select XEN_XENBUS_FRONTEND
>         help
> 
> 
> Do you have a kernel config with INPUT=m that I can use to test with?

You can easily set that in any config if you disable CONFIG_VT. I don't
think it's worth spending more time on that, as everyone seems to be
happy with just removing the 'select', and I've sent a replacement
patch to do that.

	Arnd

Patch

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 1f2337a..303df24 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -721,7 +721,7 @@  config INPUT_CMA3000_I2C
 
 config INPUT_XEN_KBDDEV_FRONTEND
 	tristate "Xen virtual keyboard and mouse support"
-	depends on XEN
+	depends on XEN && INPUT
 	default y
 	select XEN_XENBUS_FRONTEND
 	help