nRF9160 mqtt_simple SES build error

[Harry Wei]

Hi, Sir:

I am developing nRF9160 DK(pca10090) with mqtt_simple example in nRF Connect SDK(ncs/nrf/samples/nrf9160/mqtt_simple).  Firstly build the example , build OK, but  I set CONFIG_DNS_RESOLVER =y, rebuild again, there were 2 errors:

how to eliminate these errors?

Harry

Best Wishes!

[Didrik Rokhaug]

Hi.

May I ask what it is you want to achieve?

The mqtt_simple sample already does hostname resolution (via getaddrinfo), so there should be no need for doing your own DNS lookup.

Also, I can not see any errors in the picture. What were the errors you got?

Best regards,

Didrik

[Harry Wei]

Hi, Didrik:

I tested mqtt_simple in nb-lot mode, I found it always print error when the code running in nRF9160:

ERROR: getaddrinfo failed 22
ERROR: mqtt_connect -47

I have tested my SIM card in at_client with LTE Link Monitor, it works well, when I read SYSTEMMODE, it returned

AT%XSYSTEMMODE?
%XSYSTEMMODE: 0,1,0,0
OK


AT+COPS=3,2
OK
AT+COPS?+COPS: 0,2,"46000",9
OK
AT%XCBAND%XCBAND: 8
OK
AT+CGDCONT?+CGDCONT: 0,"IP","CMNBIOT","100.80.79.43",0,0
OK
AT+CGACT?+CGACT: 0,1
OK

 I guess there may be a problem with DNS, so I modified the configuration mentioned above, after that, build errors:

  /home/hurry/ncs/nrf/samples/nrf9160/mqtt_simple/build_nrf9160_pca10090ns/zephyr/include/generated/autoconf.h (22.11.2019 09:49:50) is newer than zephyr/CMakeFiles/zephyr_prebuilt.dir/misc/empty_file.c.obj (22.11.2019 09:30:40).
  Compiling 'empty_file.c'
  zephyr/CMakeFiles/zephyr_prebuilt.dir/misc/empty_file.c.obj (22.11.2019 09:50:26) is newer than zephyr/zephyr_prebuilt.elf (22.11.2019 09:30:40).
  Linking 'zephyr_prebuilt.elf'
    B       976 KB     11.05%
    B       128 KB     26.83%
    B         2 KB      5.86%
    In function `dns_resolve_init':
    undefined reference to `net_context_get'
    undefined reference to `net_context_bind'
    ld returned 1 exit status
Build failed

In china , the common DNS server is 114.114.114.114, so I added this DNS serverwe,

Best regards,

Harry