On Wed, 27 Oct 2021, Javier Martinez Canillas <javierm@xxxxxxxxxx> wrote: > 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@xxxxxxxxxxxxxxxxx> > Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx> Please see [1]. I think it's a big mess. I don't think this is the fix either. BR, Jani. [1] https://lore.kernel.org/r/878ryeit9i.fsf@xxxxxxxxx > --- > > 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 -- Jani Nikula, Intel Open Source Graphics Center
