What is the correct way to build 32-bit libcurl on freebsd? - libcurl

Question

I need to build a 32 bit libcurl.so on freebsd.
If I run ./configure like this:
CFLAGS="-m32" CPPFLAGS="-m32" LDFLAGS="-L/usr/lib32 -m32" ./configure --prefix=/usr/home/debby/libcurl2
I get the following errors in config.log:
configure:4373: checking whether the C compiler works
configure:4395: gcc -m32 -m32 -L/usr/lib32 -m32 conftest.c >&5
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/lib/crt1.o' is incompatible with i386 output
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/lib/crti.o' is incompatible with i386 output
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/local/lib/gcc6/gcc/x86_64-portbld-freebsd11.1/6.4.0/crtbegin.o' is incompatible with i386 output
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/local/lib/gcc6/gcc/x86_64-portbld-freebsd11.1/6.4.0/crtend.o' is incompatible with i386 output
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/lib/crtn.o' is incompatible with i386 output
Am I even approaching this the right way? Should I be specifying --build and --host on the ./configure command line instead, and if so what values?
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UPDATE
Using the first link suggested by #Wodin I ran configure as follows:
export CFLAGS="-m32 -march=i686 -mmmx -msse -msse2 -mfancy-math-387 -DCOMPAT_32BIT"
#export CPPFLAGS="-m32 -march=i686 -mmx -msse -msse2 -DCOMPAT_32BIT"
export LDFLAGS="-m32 -L/usr/lib32 -B/usr/lib32"
./configure --prefix=/usr/home/debby/libcurl
make then fails because I don't have the 32 bit runtime libraries
[debby#GServerBuild ~/curl-7.60.0]$ make install
Making install in lib
CCLD libcurl.la
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/lib/crti.o' is incompatible with i386 output
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/local/lib/gcc6/gcc/x86_64-portbld-freebsd11.1/6.4.0/crtbeginS.o' is incompatible with i386 output
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/local/lib/gcc6/gcc/x86_64-portbld-freebsd11.1/6.4.0/crtendS.o' is incompatible with i386 output
/usr/local/bin/ld: i386:x86-64 architecture of input file `/usr/lib/crtn.o' is incompatible with i386 output
collect2: error: ld returned 1 exit status
*** Error code 1
Based on the second link provided it seems I need to build those libraries from /usr/src which is empty.
I am trying to get src using fetch -o /tmp ftp://ftp.freebsd.org/pub/uname -s/releases/uname -m/uname -r | cut -d'-' -f1,2/src.txz as described here: https://unix.stackexchange.com/questions/204956/how-do-you-install-the-freebsd10-kernel-sources
and will put an update here on how the rest goes

Answer 1

You're using /usr/local/bin/ld which is the binutils from ports. Probably doesn't have 32 bit support. Try setting LD.
LD=/usr/bin/ld CFLAGS="-m32" CPPFLAGS="-m32" LDFLAGS="-L/usr/lib32" ./configure --libdir=/usr/local/lib32
Also I checked the file after with readelf.
readelf -h lib/.libs/libcurl.so
ELF Header:
Magic: 7f 45 4c 46 01 01 01 09 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: FreeBSD
The best way would be to make a copy of the Makefile in ports and set.
PKGNAMEPREFIX="lib32-"
CFLAGS+="-m32"
CPPFLAGs+="-m32"
LDFLAGS+="-L/usr/lib32"
CONFIGURE_ARGS+="--libdir="${LOCALBASE}/lib32"