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I have the sources of the kernel of an embedded Linux box (specifically a QNAP NAS) which is running a 64-bit v3.12.6 Linux kernel, together with the kernel config files.

What I'm trying to do is adding DVB support to that kernel, by adding kernel modules which I can then add to the system using insmod. However, using this version, I'm unable to compile dvb-core.ko which is only available built-in (i.e. CONFIG_DVB_CORE=y instead of CONFIG_DVB_CORE=m).

I've looked at the config file that's related to my box model and there are no DVB config switches set:

# cat ../../kernel_cfg/TS-X53/linux-3.12.6-x86_64-hal.cfg | grep DVB
# CONFIG_DVB_DUMMY_FE is not set

So I've copied that file as .config in the kernel sources directory and run make menuconfig. I checked the option:

Device Drivers -> Multimedia Support -> Digital TV Support

It's not possible to hit M on that line so I hit Y; and after enabling it, if I search for DVB_CORE (using the / key), I get:

---------------------------- Search Results -----------------------------
| Symbol: DVB_CORE [=y]                                                 |  
| Type  : tristate                                                      |  
|   Defined at drivers/media/Kconfig:117                                |  
|   Depends on: MEDIA_SUPPORT [=y] && MEDIA_DIGITAL_TV_SUPPORT [=y]     |  
|   Selects: CRC32 [=y]                                                 |
-------------------------------------------------------------------------

So if then I enable the various tuner drivers as a module (such as dvb-usb-dib0700.ko), save, exit and then run make modules, I get all the tuner .ko files but not dvb-core.ko which is necessary to my system to load the other dependent .ko files. These are the config switches after exiting:

# cat .config | grep DVB
CONFIG_DVB_CORE=y
CONFIG_DVB_NET=y
CONFIG_DVB_MAX_ADAPTERS=8
# CONFIG_DVB_DYNAMIC_MINORS is not set
CONFIG_DVB_USB=m
# CONFIG_DVB_USB_DEBUG is not set
# CONFIG_DVB_USB_A800 is not set
# CONFIG_DVB_USB_DIBUSB_MB is not set
# CONFIG_DVB_USB_DIBUSB_MC is not set
CONFIG_DVB_USB_DIB0700=m
# CONFIG_DVB_USB_UMT_010 is not set
# CONFIG_DVB_USB_CXUSB is not set
# CONFIG_DVB_USB_M920X is not set
# CONFIG_DVB_USB_DIGITV is not set
# CONFIG_DVB_USB_VP7045 is not set
# CONFIG_DVB_USB_VP702X is not set
# CONFIG_DVB_USB_GP8PSK is not set
# CONFIG_DVB_USB_NOVA_T_USB2 is not set
# CONFIG_DVB_USB_TTUSB2 is not set
# CONFIG_DVB_USB_DTT200U is not set
# CONFIG_DVB_USB_OPERA1 is not set
# CONFIG_DVB_USB_AF9005 is not set
# CONFIG_DVB_USB_PCTV452E is not set
# CONFIG_DVB_USB_DW2102 is not set
# CONFIG_DVB_USB_CINERGY_T2 is not set
# CONFIG_DVB_USB_DTV5100 is not set
# CONFIG_DVB_USB_FRIIO is not set
# CONFIG_DVB_USB_AZ6027 is not set
# CONFIG_DVB_USB_TECHNISAT_USB2 is not set
# CONFIG_DVB_USB_V2 is not set
# CONFIG_DVB_TTUSB_BUDGET is not set
# CONFIG_DVB_TTUSB_DEC is not set
# CONFIG_DVB_B2C2_FLEXCOP_USB is not set
# DVB-S (satellite) frontends
# DVB-T (terrestrial) frontends
CONFIG_DVB_DIB3000MC=m
CONFIG_DVB_DIB7000M=m
CONFIG_DVB_DIB7000P=m
# DVB-C (cable) frontends
CONFIG_DVB_LGDT3305=m
CONFIG_DVB_S5H1411=m
CONFIG_DVB_DIB8000=m
CONFIG_DVB_TUNER_DIB0070=m
CONFIG_DVB_TUNER_DIB0090=m
# SEC control devices for DVB-S
# CONFIG_DVB_DUMMY_FE is not set

If I edit the .config file manually and put CONFIG_DVB_CORE=m save and then make modules nothing changes:

# make modules
scripts/kconfig/conf --silentoldconfig Kconfig
#
# configuration written to .config
#
make[1]: Nothing to be done for `relocs'.
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CALL    scripts/checksyscalls.sh
  Building modules, stage 2.
  MODPOST 195 modules

The dvb-core.ko is still not compiled, and also the setting is reverted:

# cat .config | grep DVB_CORE
CONFIG_DVB_CORE=y

So my question is: how can I compile dvb-core.ko as a kernel module?

Be aware that using the previous kernel sources, which were using kernel 3.4.6, I could do this easily with the make menuconfig as there I was able to set M on the DVB setting. But the menu was different as DVB was here:

Device Drivers -> Multimedia Support -> DVB for Linux

And this was the result of the search for DVB_CORE:

---------------------------- Search Results -----------------------------
| Symbol: DVB_CORE [=m]                                                 |  
| Type  : tristate                                                      |  
| Prompt: DVB for Linux                                                 |  
|   Defined at drivers/media/Kconfig:69                                 |  
|   Depends on: MEDIA_SUPPORT [=y]                                      |  
|   Location:                                                           |  
|     -> Device Drivers                                                 |  
|       -> Multimedia support (MEDIA_SUPPORT [=y])                      |  
|   Selects: CRC32 [=y]                                                 |  
-------------------------------------------------------------------------

And the (old) config switches:

# cat .config | grep DVB
CONFIG_DVB_CORE=m
CONFIG_DVB_NET=y
CONFIG_VIDEO_BT848_DVB=y
CONFIG_DVB_MAX_ADAPTERS=8
# CONFIG_DVB_DYNAMIC_MINORS is not set
CONFIG_DVB_CAPTURE_DRIVERS=y
CONFIG_DVB_AV7110=m
# CONFIG_DVB_AV7110_OSD is not set
CONFIG_DVB_BUDGET_CORE=m
CONFIG_DVB_BUDGET=m
CONFIG_DVB_BUDGET_CI=m
CONFIG_DVB_BUDGET_AV=m
CONFIG_DVB_BUDGET_PATCH=m
CONFIG_DVB_USB=m
# CONFIG_DVB_USB_DEBUG is not set
CONFIG_DVB_USB_A800=m
CONFIG_DVB_USB_DIBUSB_MB=m
CONFIG_DVB_USB_DIBUSB_MB_FAULTY=y
CONFIG_DVB_USB_DIBUSB_MC=m
CONFIG_DVB_USB_DIB0700=m
... cut ...
virtualdj
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1 Answers1

1

Apparently the solution was easy to apply, but not so easy to guess. To build dvb-core.ko as a module, I had to go back on the menu:

Device Drivers -> Multimedia support

There, Multimedia support was already marked as Y by the kernel configuration file:

<*> Multimedia Support --->

The solution is selecting Multimedia Support and pressing M to mark it as a module:

<M> Multimedia Support --->

So basically the module selection has to be done on the parent menu, while I initially tought it was on Digital TV Support. Then when searching for DVB_CORE I correctly get:

---------------------------- Search Results -----------------------------
| Symbol: DVB_CORE [=m]                                                 |  
| Type  : tristate                                                      |  
|   Defined at drivers/media/Kconfig:117                                |  
|   Depends on: MEDIA_SUPPORT [=m] && MEDIA_DIGITAL_TV_SUPPORT [=y]     |  
|   Selects: CRC32 [=y]                                                 |
-------------------------------------------------------------------------
virtualdj
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