LinuxQuestions.org - [SOLVED] Cross-compiling applications?

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Cross-compiling applications?

Hello

I checked the Documentation section on the Plug Computer site, but didn't find how to set up a cross-compiler on a PC running Linux, and compile an application for the SheevaPlug (armv5tel processor: Feroceon 88FR131 rev 1 (v5l)).

After upgrading the SheevaPlug from its stock Ubuntu 9.04 to Debian 6, I noticed that the latest release of Nginx is 0.7.67, while support for the uwsgi protocol requires release 0.8.40 or newer.

Is there a good tutorial on how to cross-compile on Linux for the SheevaPlug?

Thank you.

Before you start cross compiling, do you have a cross compiler (or, more accurately, a cross toolchain)? There are probably vendor supplied cross toolchains for the SheevaPlug; I'll let you explore that. Armed with enough knowledge of your target architecture, you can build your own. I like crosstool-NG for that.
Once installed, most applications that use the common 'configure' procedure allow you the choose the cross target architecture as a configure option; typically

Code:

#

PATH=$PATH:/the/path/to/your/cross/toolchain/binaries



#

#  One cross toolchain I use has binaries named like 'arm-unknown-linux-gnueabi-gcc'

#  The following will coerce the Makefile to have to appropriate prefix for all of the tools.

./configure --host=arm-unknown-linux-gnueabi

--- rod.

Thanks for the infos. The ARM architecture does seem to be complicated enough that a lot of people do need to build their own toolchain.

However, before I invest time in this, Marvell provides a binary toolchain: "Host SW Support Package For Linux".

After unzipping the file, I get two BZ2 files which untar into two directories: gcc/ and rootfsv1.0/, respectively:

Code:

~/LinuxHost# ll gcc

drwxr-xr-x  6 fred fred 4096 Feb 26  2008 arm-none-linux-gnueabi/

drwxr-xr-x  2 fred fred 4096 Feb 26  2008 bin/

drwxr-xr-x  3 fred fred 4096 Feb 26  2008 distributed/

drwxr-xr-x  2 fred fred 4096 Feb 26  2008 include/

drwxr-xr-x  2 fred fred 4096 Feb 26  2008 info/

drwxr-xr-x  3 fred fred 4096 Feb 26  2008 lib/

drwxr-xr-x  3 fred fred 4096 Feb 26  2008 libexec/

drwxr-xr-x  4 fred fred 4096 Feb 26  2008 man/

drwxr-xr-x  8 fred fred 4096 Feb 26  2008 share/



~/LinuxHost# ll rootfsv1.0/

drwxr-xr-x  2 root root  4096 Feb 26  2008 bin/

drwxr-xr-x  4 root root 36864 Feb 26  2008 dev/

drwxr-xr-x  3 root root  4096 Feb 26  2008 etc/

drwxr-xr-x  2 root root  4096 Feb 26  2008 lib/

lrwxrwxrwx  1 root root    11 Feb 25  2009 linuxrc -> bin/busybox*

drwxr-xr-x  2 root root  4096 Feb 25  2009 mnt/

drwxr-xr-x  2 root root  4096 Feb 26  2008 proc/

drwxr-xr-x  2 root root  4096 Feb 26  2008 sbin/

drwxr-xr-x 10 root root  4096 Feb 26  2008 usr/

I have a few more questions:
1. Running "gcc/bin/arm-none-linux-gnueabi-gcc -o hello hello.c" did compile a shared "Hello, world!" binary that I could run succesfuly on the SheevaPlug: How did the compiler know where to find the include + library?

Code:

~/LinuxHost/gcc/bin# file hello

hello: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.14, not stripped



SheevaPlug/tmp# ldd hello

        libc.so.6 => /lib/libc.so.6 (0x40004000)

        /lib/ld-linux.so.3 (0x2a000000)

Could it be that binaries are hard-linked to find includes + libraries?

2. "file hello" says "for GNU/Linux 2.6.14: Is it because the toolchain was built with that older release of Linux?

3. Why did Marvell provide a rootfs?

4. What should I do to compile real applications? Is it just a matter of editing PATH to include "/home/fred/LinuxHost/gcc" and using the right options in "./configure"?

Thank you.

I think these questions have been answered in a startlingly similar recent thread on LQ.

Yes, the first question was answered in that other thread :-)

What about the others?

2. "file hello" says "for GNU/Linux 2.6.14: Is it because the toolchain was built with that older release of Linux?

3. Why did Marvell provide a rootfs?

Generally, a toolchain gets built against a particular kernel version. That accounts for the result of the file command, I believe. In systems I've used, file also reports the CPU architecture of the specific executable.
The root filesystem is probably just a skeleton filesystem that is the sysroot for the toolchain, so it can find libraries, header files and ancillary toolchain components. Ideally, the sysroot files exactly match the respective target filesystem.

--- rod.