diff mbox

xen kconfig: clarify INPUT_XEN_KBDDEV_FRONTEND select

Message ID 1455278707-2008263-1-git-send-email-arnd@arndb.de (mailing list archive)
State New, archived
Headers show

Commit Message

Arnd Bergmann Feb. 12, 2016, 12:04 p.m. UTC
The Xen framebuffer driver selects the xen keyboard driver, so the latter
will be built-in if XEN_FBDEV_FRONTEND=y. However, when CONFIG_INPUT
is a loadable module, this configuration cannot work. On mainline kernels,
the symbol will be enabled but not used, while in combination with
a patch I have to detect such useless configurations, we get the
expected link failure:

drivers/input/built-in.o: In function `xenkbd_remove':
xen-kbdfront.c:(.text+0x2f0): undefined reference to `input_unregister_device'
xen-kbdfront.c:(.text+0x30e): undefined reference to `input_unregister_device'

This changes the dependencies of XEN_FBDEV_FRONTEND so it cannot be
built-in if CONFIG_INPUT=m && CONFIG_INPUT_MISC=y, as that would result
in the broken select.

As usual, we would be much better off without the 'select', but removing
it now would likely break existing user configurations that depend on
it, so this adds another hack on top to get it working.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 36c1132e34bd ("xen kconfig: fix select INPUT_XEN_KBDDEV_FRONTEND")
---
 drivers/video/fbdev/Kconfig | 1 +
 1 file changed, 1 insertion(+)

Comments

Andrew Jones Feb. 12, 2016, 1:56 p.m. UTC | #1
On Fri, Feb 12, 2016 at 01:04:40PM +0100, Arnd Bergmann wrote:
> The Xen framebuffer driver selects the xen keyboard driver, so the latter
> will be built-in if XEN_FBDEV_FRONTEND=y. However, when CONFIG_INPUT
> is a loadable module, this configuration cannot work. On mainline kernels,
> the symbol will be enabled but not used, while in combination with
> a patch I have to detect such useless configurations, we get the
> expected link failure:
> 
> drivers/input/built-in.o: In function `xenkbd_remove':
> xen-kbdfront.c:(.text+0x2f0): undefined reference to `input_unregister_device'
> xen-kbdfront.c:(.text+0x30e): undefined reference to `input_unregister_device'
> 
> This changes the dependencies of XEN_FBDEV_FRONTEND so it cannot be
> built-in if CONFIG_INPUT=m && CONFIG_INPUT_MISC=y, as that would result
> in the broken select.
> 
> As usual, we would be much better off without the 'select', but removing
> it now would likely break existing user configurations that depend on
> it, so this adds another hack on top to get it working.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: 36c1132e34bd ("xen kconfig: fix select INPUT_XEN_KBDDEV_FRONTEND")
> ---
>  drivers/video/fbdev/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> 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
> -- 
> 2.7.0
>

Reviewed-by: Andrew Jones <drjones@redhat.com>

Thanks,
drew 
--
To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
diff mbox

Patch

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