How to use readline library when compiling for imx7

Technical Support
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1

Hi,
Could you please suggest me on how can I use readline lib (tab auto complete) functions when building code with gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf for iMX7d?

arm-linux-gnueabihf-gcc -o test main.c -l readline
/usr/lib/gcc-cross/arm-linux-gnueabihf/7/…/…/…/…/arm-linux-gnueabihf/bin/ld: cannot find -lreadline
collect2: error: ld returned 1 exit status

gcc -o test main.c -l readline
NO ERROR

Thank you
Neeraj

2

Greetings,

There are a lot of unknowns for us here. Are you including the readline library in your C code properly? Do you have the readline development libraries installed on your development PC? Or maybe your readline libraries are installed in a non-standard location and need to be specified to the compiler.

Perhaps try compiling a simple readline example program to eliminate any complexity initially. For example the example in this forum: c - using readline() for completion - Stack Overflow

Unfortunately as of now it’s hard to tell what went wrong from the information given.

Best Regards,
Jeremias

3

Hi @jeremias.tx ,
If you see my message again… you will find that I shared below info already:

  1. When I compile it using gcc main.c (which has readline test code) in my PC it works
  2. When I do cross compilation for arm I see this issue.

Thank you
Neeraj

4

In that case it would appear then that the toolchain you are using for cross-compilation doesn’t have readline library/support. Can you check the toolchain libraries/header files if there’s anything readline related at all?

If not you’ll most likely need to create a new toolchain/sdk with Yocto that has support for readline.

Best Regards,
Jeremias

5

Hi @jeremias.tx
Thanks for understanding.
Could you please point me some link where I can get the arm toolchain for imx7d which supports readline?

Thank you
Neeraj

6

Well first you’ll need to setup a Yocto build that matches the version of our BSP you are working on as detailed here: Build a Reference Image with Yocto Project/OpenEmbedded | Toradex Developer Center

Then you need to modify the image to add readline support to the image I believe there’s a generic readline recipe in the standard openembedded-core meta-layer. Once you’ve done this you can then build an sdk as detailed here: Linux SDKs | Toradex Developer Center

If everything went correctly then this SDK should have all the libraries and header files corresponding to whatever packages were built into the image. Which if the readline package was added correctly would mean a toolchain that has readline libraries and header files.

Best Regards,
Jeremias

7

@jeremias.tx
Thank you for details, let me work and update you.

8

Perfect. We will wait for your results.