Enabling the CONFIG_DRM_FBDEV_EMULATION Kconfig symbol can lead to linker errors, if CONFIG_DRM_KMS_HELPER is built-in but CONFIG_FB as a module.
Because in that case the drm_kms_helper.o object will have references to symbols that are defined in the fb.ko module, i.e:
$ make bzImage modules DESCEND objtool CALL scripts/atomic/check-atomics.sh CALL scripts/checksyscalls.sh CHK include/generated/compile.h GEN .version CHK include/generated/compile.h UPD include/generated/compile.h CC init/version.o AR init/built-in.a LD vmlinux.o MODPOST vmlinux.symvers MODINFO modules.builtin.modinfo GEN modules.builtin LD .tmp_vmlinux.kallsyms1 ld: drivers/gpu/drm/drm_fb_helper.o: in function `drm_fb_helper_resume_worker': drm_fb_helper.c:(.text+0x2a0): undefined reference to `fb_set_suspend' ...
To prevent this, make following changes to the config option dependencies:
* Depend on FB && !(DRM_KMS_HELPER=y && FB=m), to avoid invalid configs. * Depend on DRM_KMS_HELPER instead selecting it, to avoid circular deps.
Reported-by: Justin M. Forbes jforbes@fedoraproject.org Signed-off-by: Javier Martinez Canillas javierm@redhat.com ---
This fixes linker errors found when building the Fedora kernel package for the s390x architecture:
https://kojipkgs.fedoraproject.org//work/tasks/9849/77859849/build.log
drivers/gpu/drm/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index cea777ae7fb9..9a21e57b4a0d 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -103,8 +103,8 @@ config DRM_DEBUG_DP_MST_TOPOLOGY_REFS config DRM_FBDEV_EMULATION bool "Enable legacy fbdev support for your modesetting driver" depends on DRM - depends on FB - select DRM_KMS_HELPER + depends on FB && !(DRM_KMS_HELPER=y && FB=m) + depends on DRM_KMS_HELPER select FB_CFB_FILLRECT select FB_CFB_COPYAREA select FB_CFB_IMAGEBLIT