On Mon, 16 Aug 2021, Jackie Liu <liu.yun@xxxxxxxxx> wrote: > Hi Jani. > > My CI report an randconfigs build failed. there are: > > drm_fb_helper.c:(.text+0x302): undefined reference to `fb_set_suspend' > drm_fb_helper.c:(.text+0xaea): undefined reference to `register_framebuffer' > drm_fb_helper.c:(.text+0x1dcc): undefined reference to `framebuffer_alloc' > ld: drm_fb_helper.c:(.text+0x1dea): undefined reference to `fb_alloc_cmap' > ld: drm_fb_helper.c:(.text+0x1e2f): undefined reference to `fb_dealloc_cmap' > ld: drm_fb_helper.c:(.text+0x1e5b): undefined reference to > `framebuffer_release' > drm_fb_helper.c:(.text+0x1e85): undefined reference to > `unregister_framebuffer' > drm_fb_helper.c:(.text+0x1ee9): undefined reference to `fb_dealloc_cmap' > ld: drm_fb_helper.c:(.text+0x1ef0): undefined reference to > `framebuffer_release' > drm_fb_helper.c:(.text+0x1f96): undefined reference to > `fb_deferred_io_cleanup' > drm_fb_helper.c:(.text+0x203b): undefined reference to `fb_sys_read' > drm_fb_helper.c:(.text+0x2051): undefined reference to `fb_sys_write' > drm_fb_helper.c:(.text+0x208d): undefined reference to `sys_fillrect' > drm_fb_helper.c:(.text+0x20bb): undefined reference to `sys_copyarea' > drm_fb_helper.c:(.text+0x20e9): undefined reference to `sys_imageblit' > drm_fb_helper.c:(.text+0x2117): undefined reference to `cfb_fillrect' > drm_fb_helper.c:(.text+0x2172): undefined reference to `cfb_copyarea' > drm_fb_helper.c:(.text+0x21cd): undefined reference to `cfb_imageblit' > drm_fb_helper.c:(.text+0x2233): undefined reference to `fb_set_suspend' > drm_fb_helper.c:(.text+0x22b0): undefined reference to `fb_set_suspend' > drm_fb_helper.c:(.text+0x250f): undefined reference to `fb_deferred_io_init' > > The main reason is because DRM_FBDEV_EMULATION is built-in, and > CONFIG_FB is compiled as a module. DRM_FBDEV_EMULATION is not a module, it's just a config knob. drm_fb_helper.ko is the module, enabled via DRM_KMS_HELPER, and it has an implicit dependency on FB, and DRM_FBDEV_EMULATION selects DRM_KMS_HELPER. Select just breaks dependencies in all kinds of ways. This might help in config DRM_KMS_HELPER, and it might help the reader because it's factual: depends on FB if DRM_FBDEV_EMULATION BR, Jani. > > -- > Jackie Liu > > 在 2021/8/16 下午3:01, Jani Nikula 写道: >> On Mon, 16 Aug 2021, Jackie Liu <liu.yun@xxxxxxxxx> wrote: >>> From: Jackie Liu <liuyun01@xxxxxxxxxx> >>> >>> When CONFIG_DRM_FBDEV_EMULATION is compiled to y and CONFIG_FB is m, the >>> compilation will fail. we need make that dependency explicit. >> >> What's the failure mode? Using select here is a bad idea. >> >> BR, >> Jani. >> >>> >>> Reported-by: k2ci <kernel-bot@xxxxxxxxxx> >>> Signed-off-by: Jackie Liu <liuyun01@xxxxxxxxxx> >>> --- >>> drivers/gpu/drm/Kconfig | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig >>> index 7ff89690a976..346a518b5119 100644 >>> --- a/drivers/gpu/drm/Kconfig >>> +++ b/drivers/gpu/drm/Kconfig >>> @@ -98,7 +98,7 @@ 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 FB >>> select DRM_KMS_HELPER >>> select FB_CFB_FILLRECT >>> select FB_CFB_COPYAREA >> -- Jani Nikula, Intel Open Source Graphics Center
