usb_claim_interface error -6

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oz1sej
Posts: 6
Joined: Sun Feb 12, 2017 5:39 pm

usb_claim_interface error -6

Post by oz1sej » Mon Feb 10, 2020 4:32 pm

I've installed rtl-sdr on a raspberry pi. Now, since I'm going to use it remotely, I want to use Stephen Blinick's ring buffer rewrite of rtl_tcp as detailed here: https://www.rtl-sdr.com/significantly-i ... g-buffers/

Unfortunately, I started out by installing rtl-sdr. Now, when I run my local copy of Stephen's rtl-sdr, I get

Code: Select all

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.

usb_claim_interface error -6
Failed to open rtlsdr device #0.
I've tried removing the official rtl-sdr, but that didn't change anything.

What does it mean that the device is claimed by a second instance of librtlsdr? How do I control, which instance of librtlsdr can claim the device?

Aussie Susan
Posts: 41
Joined: Sun Jul 31, 2016 1:55 am

Re: usb_claim_interface error -6

Post by Aussie Susan » Tue Feb 11, 2020 2:33 am

Did you blacklist the RTL-SDR to stop the default kernel driver from grabbing the interface (the first thing the error message mentioned)?
I also got this message when I accidentally tried to run two of the RTL-SDR apps at the same time.
Susan

oz1sej
Posts: 6
Joined: Sun Feb 12, 2017 5:39 pm

Re: usb_claim_interface error -6

Post by oz1sej » Tue Feb 11, 2020 7:11 am

No I didn't - maybe I should try that! The reasons I didn't were 1. I don't know how to, 2. I was afraid that the two copies of rtl-sdr would use the same kernel module, so if I blacklisted it, the other copy wouldn't work either.

Would you happen to know how to blacklist a kernel module?

oz1sej
Posts: 6
Joined: Sun Feb 12, 2017 5:39 pm

Re: usb_claim_interface error -6

Post by oz1sej » Tue Feb 11, 2020 9:26 am

Found out - it works. Thank you! :)

Aussie Susan
Posts: 41
Joined: Sun Jul 31, 2016 1:55 am

Re: usb_claim_interface error -6

Post by Aussie Susan » Wed Feb 12, 2020 1:28 am

Glad to hear it.
The things that you seemed to be misunderstanding was the word 'driver'. This is a part of the Linux kernel and,unless you blacklist it, it will grab the RTL-SDR interface and expect that all of the user software will use it to talk to the device.
This works in exactly the same way as a disk driver - you talk to it and it takes care of the low level details that vary from one disk type to another.
In this case you don't want that driver to be running.
Susan

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