topic Re: Makefile Related in Operating System - Linux

Make file Related

Anil Kumar Malepati — Mon, 26 May 2008 11:50:05 GMT

How to make .o files to get created in a different directory and how to make use of them (from different directories) in linking?

Re: Makefile Related

Dennis Handly — Sun, 11 Sep 2011 21:59:25 GMT

You can create your own compile rules:
$(objdir)/foo.o: foo.c
$(CC) -o $@ -c foo.c $(CFLAGS)

And when you link, you use a macro with a list of all of the objects created as above.

Re: Make file Related

Peter Nikitka — Mon, 26 May 2008 15:46:37 GMT

Hi,

you can else use the VPATH macro to reference source files not residing in the current dir (see manual).

For linking it's best to build libraries out of your object files (perhaps one lib per directory?) and reference these.

In dir1/Makefile:
...
OBJS=$(SRCS:.c=.o)
$(LIBDIR)/libdir1.a: $(OBJS)
ar c $@ $(OBJS)

In exe/Makefile:
...
USERLIBS=-L$(LIBDIR) -ldir1 -ldir2 ...
...
myexe:
$(CC) -o $@ ... $(USERLIBS) ...

mfG Peter

Re: Make file Related

Anil Kumar Malepati — Tue, 27 May 2008 07:04:03 GMT

I tried using VPATH. But it doesn't find the source files in a different directory. Following is the make file contents.

LIBDIR=${PWD}/lib
BINDIR=${PWD}/bin
SRCDIR=${PWD}/src

VPATH=${SRCDIR}

all: clean ${LIBDIR}/session.o
#${LIBDIR}/session.o: ${SRCDIR}/session.c ${SRCDIR}/session.h
# ${CC} ${CFLAGS} -o $@ -c ${SRCDIR}/session.c

${LIBDIR}/session.o: session.c session.h
${CC} ${CFLAGS} -o $@ -c session.c

clean:
rm -f ${LIBDIR}/*.o
rm -f ${BINDIR}/*

Make fails with the following error

Re: Make file Related

Anil Kumar Malepati — Tue, 27 May 2008 07:12:10 GMT

Forgot pasting the error in my reply (above).
(Bundled) cc: error 1913: `session.c' does not exist or cannot be read
*** Error exit code 1

Re: Makefile Related

Dennis Handly — Sun, 11 Sep 2011 22:00:35 GMT

>I tried using VPATH. But it doesn't find the source files in a different directory.

Why are you using new-fangled VPATH?
Why not the tried and true relative path that points exactly to it?

If you use VPATH, as with any new and hard to use option, you need to read the documentation:
http://www.gnu.org/software/automake/manual/make/General-Search.html#General-Search
http://www.gnu.org/software/automake/manual/make/Commands_002fSearch.html#Commands_002fSearch

The second link indicates you need to use "$^" instead of session.c.
Unfortunately, make(1) while it documents VPATH, it is almost useless since it doesn't mention "$^" nor say that "$<" works for anything except inference rules.

#${LIBDIR}/session.o: ${SRCDIR}/session.c ${SRCDIR}/session.h
# ${CC} ${CFLAGS} -o $@ -c ${SRCDIR}/session.c

I assume this works?

>(Bundled) cc: error 1913: `session.c' does not exist or cannot be read

This indicates that VPATH isn't working.
Also, why are you using cc_bundled(1)?