尝试交叉编译httpry的问题

Question

I'm trying to cross-compile httpry . I have already cross-compiled libpcap, but for some reason when I try to compile httpry it doesn't seem to be able to find the libpcap library.

I've had to modify the Makefile for httpry in order to attempt cross-compilation:

CC              = /usr/bin/arm-linux-gnueabi-gcc
CCFLAGS         = -Wall -O3 -funroll-loops -I/home/josh/workbench/libpcap-1.8.1
DEBUGFLAGS      = -Wall -g -DDEBUG -I/home/josh/workbench/libpcap-1.8.1

When I try compilation I get the following error:

josh@LAPTOP-D3KEQ9EM:~/workbench/httpry-0.1.8$ make
/usr/bin/arm-linux-gnueabi-gcc -Wall -O3 -funroll-loops -I/home/josh/workbench/libpcap-1.8.1 -o httpry httpry.c format.c methods.c utility.c rate.c -lpcap -lm -pthread
/usr/lib/gcc-cross/arm-linux-gnueabi/4.7/../../../../arm-linux-gnueabi/bin/ld: cannot find -lpcap
collect2: error: ld returned 1 exit status
make: *** [httpry] Error 1

So it certainly seem that LD isn't finding the library. Out of curiosity, I tried

josh@LAPTOP-D3KEQ9EM:~/workbench/httpry-0.1.8$ ld -L/home/josh/workbench/libpcap-1.8.1 -lpcap
ld: skipping incompatible /home/josh/workbench/libpcap-1.8.1/libpcap.so when searching for -lpcap
ld: skipping incompatible /home/josh/workbench/libpcap-1.8.1/libpcap.a when searching for -lpcap
ld: cannot find -lpcap

Seems like the LD I have on PATH gives the same error, and it's caused because libpcap is cross-compiled for a different architecture to my current architecture. But my cross-complication GCC doesn't use the PATH LD, it uses its own version, and when I try that I get the following

josh@LAPTOP-D3KEQ9EM:~/workbench/httpry-0.1.8$ /usr/lib/gcc-cross/arm-linux-gnueabi/4.7/../../../../arm-linux-gnueabi/bin/ld -L/home/josh/workbench/libpcap-1.8.1 -lpcap
/usr/lib/gcc-cross/arm-linux-gnueabi/4.7/../../../../arm-linux-gnueabi/bin/ld: warning: cannot find entry symbol _start; defaulting to 00000000000081e4

That's kinda weird, right? It seems like when I run ld it's able to find the library without any issues, but when GCC runs it for some reason it's not.

Am I missing something obvious? Is there a way I can find out what arguments gcc is calling ld with? I tried using -v or -### but I wasn't able to find anything useful in the output.

Thanks,

Josh

Answer 1

Seems like LD wasn't looking in the right directory. I thought -I would make sure it did, but it turns out -L was necessary too:

CC              = /usr/bin/arm-linux-gnueabi-gcc
CCFLAGS         = -Wall -O3 -funroll-loops -I/home/josh/workbench/libpcap-1.8.1 -L/home/josh/workbench/libpcap-1.8.1
DEBUGFLAGS      = -Wall -g -DDEBUG -I/home/josh/workbench/libpcap-1.8.1 -L/home/josh/workbench/libpcap-1.8.1

I'm not entirely sure why this is the case and I'd apprecate an explanation. -I has always been enough for me in the past.