> (I don't know anything about blacklisting or detaching!)
The problem is the Linux kernel DVB driver is loaded, which means it is
making the device available for TV reception. Since the device is in
use by this driver, the SDR programs can't access it.
> *Kernel driver is active, or device is claimed by second instance of
> librtlsdr.
> In the first case, please either detach or blacklist the kernel module
> (dvb_usb_rtl28xxu), or enable automatic detaching at compile time.
> *
As the message suggests, there are two solutions. The quickest is to
simply unload the driver:
sudo rmmod dvb_usb_rtl28xxu rtl2832
Not sure whether "rtl2832" on the end there is required or not, but it
can't hurt. This is only a temporary solution, as the driver will be
loaded again the next time you unplug and replug the USB device, so
you'll have to run the command again.
If this works, and you don't want to use the device for TV reception,
you can stop the module from ever being loaded, solving the problem
permanently. The exact method depends on your Linux distribution, but
for me (running Arch Linux) I create a file in /etc/modprobe.d with
a .conf extension (I called it "no-rtl.conf") with these contents:
blacklist dvb_usb_rtl28xxu
blacklist rtl2832
blacklist rtl2830
Again not sure whether it's necessary to blacklist all three of these
or just the first, but I was erring on the side of caution and chose to
list everything to do with the Realtek DVB device.
Once you have created this blacklist file, you may need to unload the
driver one last time if it was already running - the blacklist
prevents it from loading but doesn't do anything if it's already
running.
The second solution is to recompile the rtl_test program, and include
support for asking the kernel driver to let go of the device, so it can
be accessed. This may not be ideal though, because you will still have
the problem of the device being in use if you use other programs that do
not support detaching of the kernel driver.
If you're only interested in SDR use, blacklisting is the way to go.
And you can always remove the blacklist if you do want to use it for
TV one day.
Cheers,
Adam.