Segmentation fault on any radio program

[rsubtil]

I'm using an ADALM-PLUTO device, and have installed this driver to use with programs such as SigDigger. However, I get a segmentation fault in those programs. I have also tried the probe command SoapySDRUtil --probe="driver=plutosdr", but no luck.

Looking at the core dump and by compilling some libraries, I found out that the code responsible for finding devices (in PlutoSDR_Settings.cpp) is returning null values:

dev = iio_context_find_device(ctx, "ad9361-phy");
rx_dev = iio_context_find_device(ctx, "cf-ad9361-lpc");
tx_dev = iio_context_find_device(ctx, "cf-ad9361-dds-core-lpc");
this->setAntenna(SOAPY_SDR_RX, 0, "A_BALANCED");
this->setAntenna(SOAPY_SDR_TX, 0, "A");

Both dev, rx_dev and tx_dev are initialized to 0x00, causing the crash. I initially assumed it was a problem with the ad9361 driver, but after opening an issue there (https://github.com/analogdevicesinc/libad9361-iio/issues/56) it was suggested I ask here instead.

I'm using Arch Linux, and installed soapyplutosdr which should include everything needed AFAIK.

Probably a duplicate of #25, but when I compiled this I had zero warnings.

[zuckschwerdt]

If all dev are NULL that suggests that ctx wasn't usable. But it obviously wasn't null, there is a check for that. So you have a valid context (ctx) that doesn't have "ad9361-phy", "cf-ad9361-lpc", "cf-ad9361-dds-core-lpc"? Can you check with iio_info or iio_attr what's there?

[rsubtil]

The output of iio_info is:

$ Library version: 0.21 (git tag: v0.21)
Compiled with backends: local xml ip usb serial
IIO context created with local backend.
Backend version: 0.21 (git tag: v0.21)
Backend description string: Linux ricardo 5.8.5-arch1-1 #1 SMP PREEMPT Thu, 27 Aug 2020 18:53:02 +0000 x86_64
IIO context has 2 attributes:
    local,kernel: 5.8.5-arch1-1
    uri: local:
IIO context has 0 devices:

If I do iio_info --auto though, it finds the device:

$ iio_info --auto       
Library version: 0.21 (git tag: v0.21)
Compiled with backends: local xml ip usb serial
Multiple contexts found. Please select one using --uri:
    0: (Local IIO devices on HP) [local:]
    1: 0456:b673 (Analog Devices Inc. PlutoSDR (ADALM-PLUTO)), serial=104473541196000417000800f1ff1e227f [usb:1.10.5]

And then, by specifying the URI I can get device info thorugh iio_info and iio_attr (https://pastebin.com/YS6cXNc4)

[zuckschwerdt]

Ok, I suspect that we try to open that other IIO context (what is that?) and obviously there are no Pluto-specific devices there. We should make sure that the context we are looking at actually is a Puto and also maybe try to find more contexts?

[zuckschwerdt]

There is now a sanity check so we don't try to work with a non-PlutoSDR IIO context. You need to use a uri or hostname (see uri and network in https://analogdevicesinc.github.io/libiio/master/libiio/index.html#creating_context) arg to select the PlutoSDR context if the default IIO context isn't the right one.