Linked in libraries when cross-compiling

Mikael Djurfeldt

I'm trying to cross-compile a source which needs libncurses. I've built the toolchain using the image branch of your repository github.com:werecatf/source.git and I can compile and run simple binaries.

But now, I'd like to build larger projects which depend on other software packages. I have the problem that the cross-compiler doesn't seem to respect library paths.

For example, I did this:

mdj@xxx:/tmp$ mipsel-openwrt-linux-gcc foo.c -L~/src/werecatf/staging_dir/target-mipsel_24kc_musl-1.1.15/usr/lib -lncursesw
/home/mdj/src/werecatf/staging_dir/toolchain-mipsel_24kc_gcc-5.4.0_musl-1.1.15/lib/gcc/mipsel-openwrt-linux-musl/5.4.0/../../../../mipsel-openwrt-linux-musl/bin/ld: cannot find -lncursesw

What could be the problem, and what, in general, is the normal way to do this?

Best regards,
Mikael

WereCatf

@Mikael-Djurfeldt The library has been renamed to ncurses, not ncursesw, for compatibility-reasons.

Mikael Djurfeldt

@WereCatf In the directory that I gave with -L, there actually is a libncursesw.a, but it doesn't find it! Also, I've tried -lncurses...

WereCatf

@Mikael-Djurfeldt I'm not exactly a cross-compiling wizard myself, either, but here are the steps on how I compile a simple ncurses-based app. First, I use a small script called cross.sh at the root of the LEDE-sources to set up a cross-compiling environment for myself:

#!/bin/bash
pushd .
pushd `dirname $0` > /dev/null
export SCRIPTDIR=`pwd`
popd > /dev/null

cd $SCRIPTDIR
cd staging_dir/toolchain*
cd bin
export PATH=$PATH:$(pwd)
cd $SCRIPTDIR
cd staging_dir
export STAGING_DIR=$(pwd)
cd target-*
export TARGET_DIR=$(pwd)
export CC=mips-openwrt-linux-gcc
export LD=mips-openwrt-linux-ld
export CROSS_COMPILE=mipsel-openwrt-linux-
export CFLAGS="-march=24kec -mtune=24kec -mdsp -D_MIPS_ARCH_MIPS32R2"
export CPPFLAGS="-I${TARGET_DIR}/usr/include"
export LDFLAGS="-L${TARGET_DIR}/lib -L${TARGET_DIR}/usr/lib"
popd
bash

I create a file called curseshello.c:

#include <stdio.h>
#include <ncurses.h>

void main()
{
    WINDOW *vin;
    initscr();
    start_color();
    init_pair(1,COLOR_YELLOW,COLOR_BLUE);
    init_pair(2,COLOR_BLUE,COLOR_YELLOW);
    init_pair(3,COLOR_BLUE,COLOR_WHITE);
    vin=newwin(12,40,13,0);
    wmove(vin,0,5);
    wprintw(vin,"Hello, World.");
    wbkgd(vin,COLOR_PAIR(1));
    wrefresh(vin);
    getch();
    delwin(vin);
    endwin();
}

Then I proceed to call the cross.sh and then compile the above code with: mipsel-openwrt-linux-gcc $CFLAGS curseshello.c -o curseshello -lncurses $CPPFLAGS $LDFLAGS

A proper cross-compiling wizard would most likely be aghast at all the stupidity I commit here, but I only taught myself rudimentary cross-compiling like two-three weeks ago, and this method works for now, so...

Mikael Djurfeldt

@WereCatf Many thanks! I found the source of the problem: Tilde expansion doesn't work juxtaposed to -L. I just had to replace it with $HOME.

However, it strange that the tools don't respect LIBRARY_PATH---something I've also tested.

Adrian Rix

Hello,

May I ask you on which Linux Distribution you are cross compiling?

I have tried to build the tool chain (including the LEDE Image) on Kubuntu and on Ubuntu
without success by following this tutorial:

https://wiki.onion.io/Tutorials/Cross-Compile

with the toolchain from the "Onion Omega2" branch from Onion's git hub

This is the error I am getting (on latest Ubuntu LTS):

Bild Text

There had also been a couple of errors before this one that I have managed to fix by recrusive chmodding the whole directory with 777.

Mikael Djurfeldt

@Adrian-Rix Sure---I built using the "image" branch of https://github.com/WereCatf/source.git on a Debian stretch system.

Basically, once you have checked that out, you can do just

make

to get the image, however you might want to select things using

make menuconfig

first.