make: *** [Makefile:43: v4l2loopback.ko] Error 2

[Souravgoswami]

Hi, I want to run v4l2loopback on my Archlinux system.
System Info:

$ cat /proc/version
Linux version 5.8.5-xanmod1-1-xanmod (makepkg@archlinux) (clang version 10.0.1 , LLD 10.0.1) #1 SMP PREEMPT Wed, 02 Sep 2020 07:55:08 +0000

Unfortunately, whenever I run:

$ CC=clang HOSTCC=clang CXX=clang++ make

I get:

Building v4l2-loopback driver...
make -C /lib/modules/`uname -r`/build M=/ramdisk/v4l2loopback modules
make[1]: Entering directory '/usr/lib/modules/5.8.5-xanmod1-1-xanmod/build'
  CC [M]  /ramdisk/v4l2loopback/v4l2loopback.o
gcc: error: unrecognized command-line option ‘-Qunused-arguments’
gcc: error: unrecognized command-line option ‘-mno-global-merge’
make[2]: *** [scripts/Makefile.build:281: /ramdisk/v4l2loopback/v4l2loopback.o] Error 1
make[1]: *** [Makefile:1760: /ramdisk/v4l2loopback] Error 2
make[1]: Leaving directory '/usr/lib/modules/5.8.5-xanmod1-1-xanmod/build'
make: *** [Makefile:43: v4l2loopback.ko] Error 2

---

Here's my kernel configuration:

$ zcat /proc/config.gz  | egrep -i 'v4l|video'
CONFIG_ACPI_VIDEO=m
CONFIG_VIDEO_DEV=m
# Video4Linux options
CONFIG_VIDEO_V4L2=m
CONFIG_VIDEO_V4L2_I2C=y
CONFIG_VIDEO_V4L2_SUBDEV_API=y
# CONFIG_VIDEO_ADV_DEBUG is not set
# CONFIG_VIDEO_FIXED_MINOR_RANGES is not set
CONFIG_VIDEO_TUNER=m
CONFIG_V4L2_MEM2MEM_DEV=m
CONFIG_V4L2_FLASH_LED_CLASS=m
CONFIG_V4L2_FWNODE=m
CONFIG_VIDEOBUF_GEN=m
CONFIG_VIDEOBUF_DMA_SG=m
CONFIG_VIDEOBUF_VMALLOC=m
# end of Video4Linux options
CONFIG_USB_VIDEO_CLASS=m
CONFIG_USB_VIDEO_CLASS_INPUT_EVDEV=y
CONFIG_VIDEO_CPIA2=m
CONFIG_VIDEO_USBTV=m
CONFIG_VIDEO_PVRUSB2=m
CONFIG_VIDEO_PVRUSB2_SYSFS=y
CONFIG_VIDEO_PVRUSB2_DVB=y
# CONFIG_VIDEO_PVRUSB2_DEBUGIFC is not set
CONFIG_VIDEO_HDPVR=m
CONFIG_VIDEO_STK1160_COMMON=m
CONFIG_VIDEO_STK1160=m
CONFIG_VIDEO_GO7007=m
CONFIG_VIDEO_GO7007_USB=m
CONFIG_VIDEO_GO7007_LOADER=m
CONFIG_VIDEO_GO7007_USB_S2250_BOARD=m
CONFIG_VIDEO_AU0828=m
CONFIG_VIDEO_AU0828_V4L2=y
CONFIG_VIDEO_AU0828_RC=y
CONFIG_VIDEO_CX231XX=m
CONFIG_VIDEO_CX231XX_RC=y
CONFIG_VIDEO_CX231XX_ALSA=m
CONFIG_VIDEO_CX231XX_DVB=m
CONFIG_VIDEO_TM6000=m
CONFIG_VIDEO_TM6000_ALSA=m
CONFIG_VIDEO_TM6000_DVB=m
CONFIG_VIDEO_EM28XX=m
CONFIG_VIDEO_EM28XX_V4L2=m
CONFIG_VIDEO_EM28XX_ALSA=m
CONFIG_VIDEO_EM28XX_DVB=m
CONFIG_VIDEO_EM28XX_RC=m
CONFIG_VIDEO_MEYE=m
CONFIG_VIDEO_SOLO6X10=m
CONFIG_VIDEO_TW5864=m
CONFIG_VIDEO_TW68=m
CONFIG_VIDEO_TW686X=m
CONFIG_VIDEO_IVTV=m
# CONFIG_VIDEO_IVTV_DEPRECATED_IOCTLS is not set
CONFIG_VIDEO_IVTV_ALSA=m
CONFIG_VIDEO_FB_IVTV=m
CONFIG_VIDEO_FB_IVTV_FORCE_PAT=y
CONFIG_VIDEO_HEXIUM_GEMINI=m
CONFIG_VIDEO_HEXIUM_ORION=m
CONFIG_VIDEO_MXB=m
CONFIG_VIDEO_DT3155=m
CONFIG_VIDEO_CX18=m
CONFIG_VIDEO_CX18_ALSA=m
CONFIG_VIDEO_CX23885=m
CONFIG_VIDEO_CX25821=m
CONFIG_VIDEO_CX25821_ALSA=m
CONFIG_VIDEO_CX88=m
CONFIG_VIDEO_CX88_ALSA=m
CONFIG_VIDEO_CX88_BLACKBIRD=m
CONFIG_VIDEO_CX88_DVB=m
CONFIG_VIDEO_CX88_ENABLE_VP3054=y
CONFIG_VIDEO_CX88_VP3054=m
CONFIG_VIDEO_CX88_MPEG=m
CONFIG_VIDEO_BT848=m
CONFIG_VIDEO_SAA7134=m
CONFIG_VIDEO_SAA7134_ALSA=m
CONFIG_VIDEO_SAA7134_RC=y
CONFIG_VIDEO_SAA7134_DVB=m
CONFIG_VIDEO_SAA7134_GO7007=m
CONFIG_VIDEO_SAA7164=m
CONFIG_VIDEO_COBALT=m
CONFIG_VIDEO_IPU3_CIO2=m
# CONFIG_VIDEO_PCI_SKELETON is not set
CONFIG_VIDEO_CX2341X=m
CONFIG_VIDEO_TVEEPROM=m
CONFIG_VIDEOBUF2_CORE=m
CONFIG_VIDEOBUF2_V4L2=m
CONFIG_VIDEOBUF2_MEMOPS=m
CONFIG_VIDEOBUF2_DMA_CONTIG=m
CONFIG_VIDEOBUF2_VMALLOC=m
CONFIG_VIDEOBUF2_DMA_SG=m
CONFIG_VIDEOBUF2_DVB=m
CONFIG_VIDEO_SAA7146=m
CONFIG_VIDEO_SAA7146_VV=m
CONFIG_VIDEO_V4L2_TPG=m
CONFIG_V4L_PLATFORM_DRIVERS=y
CONFIG_VIDEO_CAFE_CCIC=m
CONFIG_VIDEO_VIA_CAMERA=m
CONFIG_VIDEO_CADENCE=y
CONFIG_VIDEO_CADENCE_CSI2RX=m
CONFIG_VIDEO_CADENCE_CSI2TX=m
CONFIG_VIDEO_ASPEED=m
CONFIG_V4L_MEM2MEM_DRIVERS=y
CONFIG_VIDEO_MEM2MEM_DEINTERLACE=m
CONFIG_V4L_TEST_DRIVERS=y
CONFIG_VIDEO_VIMC=m
CONFIG_VIDEO_VIVID=m
CONFIG_VIDEO_VIVID_CEC=y
CONFIG_VIDEO_VIVID_MAX_DEVS=64
CONFIG_VIDEO_VIM2M=m
CONFIG_VIDEO_VICODEC=m
CONFIG_VIDEO_IR_I2C=m
CONFIG_VIDEO_TVAUDIO=m
CONFIG_VIDEO_TDA7432=m
CONFIG_VIDEO_TDA9840=m
CONFIG_VIDEO_TDA1997X=m
CONFIG_VIDEO_TEA6415C=m
CONFIG_VIDEO_TEA6420=m
CONFIG_VIDEO_MSP3400=m
CONFIG_VIDEO_CS3308=m
CONFIG_VIDEO_CS5345=m
CONFIG_VIDEO_CS53L32A=m
CONFIG_VIDEO_TLV320AIC23B=m
CONFIG_VIDEO_UDA1342=m
CONFIG_VIDEO_WM8775=m
CONFIG_VIDEO_WM8739=m
CONFIG_VIDEO_VP27SMPX=m
CONFIG_VIDEO_SONY_BTF_MPX=m
CONFIG_VIDEO_SAA6588=m
# Video decoders
CONFIG_VIDEO_ADV7180=m
CONFIG_VIDEO_ADV7183=m
CONFIG_VIDEO_ADV7604=m
CONFIG_VIDEO_ADV7604_CEC=y
CONFIG_VIDEO_ADV7842=m
CONFIG_VIDEO_ADV7842_CEC=y
CONFIG_VIDEO_BT819=m
CONFIG_VIDEO_BT856=m
CONFIG_VIDEO_BT866=m
CONFIG_VIDEO_KS0127=m
CONFIG_VIDEO_ML86V7667=m
CONFIG_VIDEO_SAA7110=m
CONFIG_VIDEO_SAA711X=m
CONFIG_VIDEO_TC358743=m
CONFIG_VIDEO_TC358743_CEC=y
CONFIG_VIDEO_TVP514X=m
CONFIG_VIDEO_TVP5150=m
CONFIG_VIDEO_TVP7002=m
CONFIG_VIDEO_TW2804=m
CONFIG_VIDEO_TW9903=m
CONFIG_VIDEO_TW9906=m
CONFIG_VIDEO_TW9910=m
CONFIG_VIDEO_VPX3220=m
# Video and audio decoders
CONFIG_VIDEO_SAA717X=m
CONFIG_VIDEO_CX25840=m
# end of Video decoders
# Video encoders
CONFIG_VIDEO_SAA7127=m
CONFIG_VIDEO_SAA7185=m
CONFIG_VIDEO_ADV7170=m
CONFIG_VIDEO_ADV7175=m
CONFIG_VIDEO_ADV7343=m
CONFIG_VIDEO_ADV7393=m
CONFIG_VIDEO_ADV7511=m
CONFIG_VIDEO_ADV7511_CEC=y
CONFIG_VIDEO_AD9389B=m
CONFIG_VIDEO_AK881X=m
CONFIG_VIDEO_THS8200=m
# end of Video encoders
# Video improvement chips
CONFIG_VIDEO_UPD64031A=m
CONFIG_VIDEO_UPD64083=m
# end of Video improvement chips
# Audio/Video compression chips
CONFIG_VIDEO_SAA6752HS=m
# end of Audio/Video compression chips
CONFIG_VIDEO_THS7303=m
CONFIG_VIDEO_M52790=m
CONFIG_VIDEO_I2C=m
CONFIG_VIDEO_ST_MIPID02=m
CONFIG_VIDEO_APTINA_PLL=m
CONFIG_VIDEO_SMIAPP_PLL=m
CONFIG_VIDEO_HI556=m
CONFIG_VIDEO_IMX214=m
CONFIG_VIDEO_IMX219=m
CONFIG_VIDEO_IMX258=m
CONFIG_VIDEO_IMX274=m
CONFIG_VIDEO_IMX290=m
CONFIG_VIDEO_IMX319=m
CONFIG_VIDEO_IMX355=m
CONFIG_VIDEO_OV2640=m
CONFIG_VIDEO_OV2659=m
CONFIG_VIDEO_OV2680=m
CONFIG_VIDEO_OV2685=m
CONFIG_VIDEO_OV2740=m
CONFIG_VIDEO_OV5647=m
CONFIG_VIDEO_OV6650=m
CONFIG_VIDEO_OV5670=m
CONFIG_VIDEO_OV5675=m
CONFIG_VIDEO_OV5695=m
CONFIG_VIDEO_OV7251=m
CONFIG_VIDEO_OV772X=m
CONFIG_VIDEO_OV7640=m
CONFIG_VIDEO_OV7670=m
CONFIG_VIDEO_OV7740=m
CONFIG_VIDEO_OV8856=m
CONFIG_VIDEO_OV9640=m
CONFIG_VIDEO_OV9650=m
CONFIG_VIDEO_OV13858=m
CONFIG_VIDEO_VS6624=m
CONFIG_VIDEO_MT9M001=m
CONFIG_VIDEO_MT9M032=m
CONFIG_VIDEO_MT9M111=m
CONFIG_VIDEO_MT9P031=m
CONFIG_VIDEO_MT9T001=m
CONFIG_VIDEO_MT9T112=m
CONFIG_VIDEO_MT9V011=m
CONFIG_VIDEO_MT9V032=m
CONFIG_VIDEO_MT9V111=m
CONFIG_VIDEO_SR030PC30=m
CONFIG_VIDEO_NOON010PC30=m
CONFIG_VIDEO_M5MOLS=m
CONFIG_VIDEO_RJ54N1=m
CONFIG_VIDEO_S5K6AA=m
CONFIG_VIDEO_S5K6A3=m
CONFIG_VIDEO_S5K4ECGX=m
CONFIG_VIDEO_S5K5BAF=m
CONFIG_VIDEO_SMIAPP=m
CONFIG_VIDEO_ET8EK8=m
CONFIG_VIDEO_S5C73M3=m
CONFIG_VIDEO_AD5820=m
CONFIG_VIDEO_AK7375=m
CONFIG_VIDEO_DW9714=m
CONFIG_VIDEO_DW9807_VCM=m
CONFIG_VIDEO_ADP1653=m
CONFIG_VIDEO_LM3560=m
CONFIG_VIDEO_LM3646=m
CONFIG_VIDEO_GS1662=m
CONFIG_DVB_AU8522_V4L=m
CONFIG_DRM_VBOXVIDEO=m
CONFIG_VIDEOMODE_HELPERS=y
CONFIG_VIDEO_ATOMISP=m
# CONFIG_VIDEO_ATOMISP_ISP2401 is not set
CONFIG_VIDEO_ATOMISP_OV5693=m
CONFIG_VIDEO_ATOMISP_OV2722=m
CONFIG_VIDEO_ATOMISP_GC2235=m
CONFIG_VIDEO_ATOMISP_MSRLIST_HELPER=m
CONFIG_VIDEO_ATOMISP_MT9M114=m
CONFIG_VIDEO_ATOMISP_GC0310=m
CONFIG_VIDEO_ATOMISP_OV2680=m
CONFIG_VIDEO_ATOMISP_LM3554=m
CONFIG_VIDEO_IPU3_IMGU=m
CONFIG_VIDEO_USBVISION=m
CONFIG_MOST_VIDEO=m
CONFIG_THINKPAD_ACPI_VIDEO=y

[umlaeute]

the error message indicates that you are actually using gcc rather than clang. which you could easily very by passing V=1 as make arguments.

then: why are you passing the compiler as environment variables? you should use make arguments instead.
and of course: you are setting HOSTCC (?) and CXX (a C++-compiler).
but v4l2loopback is pure C, so you should pass CC instead.

make CC=clang

in any case: that's a general problem of passing the proper compiler to any kernel-module (note that the v4l2loopback-Makefile delegates the actual work to the module-makefile from your kernel), so I'm closing this as not-for-us.

[Souravgoswami]

Thanks got it compiled and working!