Cross-compiling and linking to existing .so "no symbol"

For Developers
1

Hi,

I have to cross-compile a simple program for openwrt 15.05.1 ramips, that links against libpcap.
I've downloaded the libpcap.so.1.3.0 from the package repo, and the toolchain. Then I do

mipsel-openwrt-linux-gcc udpreplay.c -o udpreplay -Ilibpcap/ -L. -l:libpcap.so.1.3.0

I get undefined reference to all pcap functions.

Then when I do

mipsel-openwrt-linux-nm -D udpreplay/libpcap.so.1.3.0

I get no symbols. How come the toolchain does not recognize its own .so?

I really don't get It.... Any idea?

Ps: exact same thing with openwrt 18.06 and libpcap1.9.1
Ps2: exact same thing if I re-cross-compile the library with the SDK instead of downloading it

2

I found a workaround; compile libpcap.a with the SDK and compile with linking to this .a. But this bug is very strange.