Cross Compile Environment - Practical Raspberry Pi - page 117

Figure 6-17. My populated build directory

There is a good reason why I am showing you my build directory. When you compile more applications that
have more dependencies, you need a clean way to find them all. Change into the libpcap directory; it's now time to
start the build. Because I won't be installing libpcap onto this machine I like to create a build directory: this way I
can use the make install tool. I have called this directory rpi-build ; you will need to create this directory under the
libpcap directory. Once you have done that it's time to run the configure command again. The full command looks
something like this:

# CC=arm-unknown-linux-gnueabi-gcc ./configure --host=arm-unknown-linux-gnueabi --with-pcap=linux
--prefix=/'pwd'/rpi-build

Let me explain the new options.

--with-pcap=linux , tells libpcap what target operating system you are
building for. After all, you may be cross compiling libpcap to run on AIX, for example.

• The first new option,

prefix=/'pwd'/rpi-build , tells the configure tool where you want to
install the binary files and libraries when you run make install .
The configure process for libpcap should run pretty quickly.
Once again, you cannot allow errors in this stage. When you are certain your configure stage is error-free, run the
make tool to build the source files. There is not much to be built for libpcap so this step should be quick. Lastly, install the
build into the rpi-build directory you created. You can do this with the make install command; note that if you had
not used the prefix option above, your build would be installed into your host system, which is not a good thing:

• The last option you see,

# make install

Take a look at Figure 6-18 for an example of a finished build of libpcap .

Figure 6-18. Libpcap installed into the rpi-build directory