12 replies to this topic

[Dirktator]

Hi,

Can anybody help me with an example Makefile to build your own apps under openembedded? I already have the created the openembedded image for my DM500+ so I have the complete oe CDK etc installed. I am not sure however which parameters are required to cross-compile using the oe libraries..

Thanks!!!!

[pieterg]

you don't have to create a makefile, assumed that the application you want to build uses GNU autotools.

In the oe build dir:

source ./env.source
bitbake devshell

then in your application dir:

source ~/oe/build/tmp/work/devshell-???/powerpc-???
oe_runconf
make

[Dirktator]

hi

- what does the source command do?
- the oe_runconf command does not execute (command not found)

[pieterg]

the source command loads all vars from a script into the environment.
And the devshell source script contains the path to oe_runconf, so you need to source it before oe_runconf works

[Dirktator]

hmm, now suppose I have some code without a .configure file?!?

[pieterg]

then theoretically you just use 'make', and hope your makefile is nicely structured, and supports crosscompiling.
But in general, non-autotools packages require you to edit the makefile, before you can crosscompile.

[pieterg]

btw, not having a configure file doesn't necessarily mean its not an autotools project.
If you have configure.in or configure.ac, you have to run autoconf to generate the configure script. (and automake to create Makefile.in's from Makefile.am's)
In that case, usually a Makefile.cvs is provided (make -f Makefile.cvs), or an autogen.sh script (./autogen.sh)

[Dirktator]

hi

compiling seems to work, but the linking process tells me:
/usr/bin/ld: big.o: Relocations in generic ELF
big.o: could not read symbols, file in wrong format

sounds like linker tries to link ppc files into intel executable or otherway around?
any idea what's missing?

[pieterg]

the problem is you're using the linker from your build system (/usr/bin/ld) instead of the cross linker.
Looks like you have to manually edit your makefile after all (let it use LD instead of a hardcoded ld, LD should be filled by the devshell script))

[Dirktator]

ok, seems to work... but the linking still fails...
now suppose I write my own famous helloworld.c and want to run this on the dreambox console, how should I compile and link this?
I created a tiny Makefile like:

ALLX = helloworld.o

all: helloworld.0
        $(CPP) -o hellow $(CPPFLAGS) $(LDFLAGS) ALLX

Sorry for these maybe stupid questions but I am pretty new to developing code with a cross compiler

[pieterg]

CPP is the precompiler, normally you should use CC

And I guess helloworld.0 (zero, not o) is a typo?

[pieterg]

and make sure LDFLAGS contains the correct -L link paths

And perhaps specify a general rule to build .o's

.o.c:
        $(CC) $(CFLAGS) -c $<

[Dirktator]

hi

replaced CPP by CC and now it works....
sometimes life is so simple

Thanks!!!