Gentoo: crossdev avr

Cross compile ?

Cross compile is name of build process which produce machine code for different architecture. For example I am also embed device developer and I produce machine code for AVR platform on x86_64 workstation. Effectively I am doing cross compile on x86_64 to AVR target. I am writing source code in C language and partly in assembler.

Why sys-devel/crossdev ?

Because it is Gentoo specific tool to manage necessary software to perform cross compile (e.g. binutils, headers, libraries, and compiler). It is very simple to use so i save some of my time during installation of crossdev environment.

Installation of AVR target

sys-devel/crossdev

I recommend latest version of sys-devel/crossdev so first of all put this ebuild to package.keywords. This package don't have USE flags so it is enough to perform:

emerge crossdev

required configuration

crossdev is using own local portage overlay to build target specific configuration. Following line is necessarily in /etc/make.conf. Of course you can use different location :)

PORTDIR_OVERLAY="/opt/local/portage"

If directory dont exist then create it

mkdir -p /opt/local/portage

crossdev is using new layout of /etc/portage/package.* . If you don't migrated to this layout then you should to it now. New layout is expecting /etc/portage/package.keywords/ (and all others) to be a directory and configuration in files inside of it. For example for AVR target you can find cross-avr there.

installation of cross compile tools

Just invoke:

crossdev -t avr

And you should see following:

 * crossdev version:      20120721
 * Host Portage ARCH:     amd64
 * Target Portage ARCH:   *
 * Target System:         avr
 * Stage:                 4 (C/C++ compiler)
 * ABIs:                  default

 * binutils:              binutils-[latest]
 * gcc:                   gcc-[latest]
 * libc:                  avr-libc-[latest]

 * CROSSDEV_OVERLAY:      /opt/local/portage
 * PORT_LOGDIR:           /var/log/portage
 * PORTAGE_CONFIGROOT:
 * Portage flags:
!!! WARNING - Cannot auto-configure CHOST avr
!!! You should edit /usr/avr/etc/portage/make.conf
!!! by hand to complete your configuration
 * Log: /var/log/portage/cross-avr-binutils.log
 * Emerging cross-binutils ...                                              [ ok ]
 * Log: /var/log/portage/cross-avr-gcc-stage1.log
 * Emerging cross-gcc-stage1 ...                                            [ ok ]
 * Log: /var/log/portage/cross-avr-avr-libc.log
 * Emerging cross-avr-libc ...                                              [ ok ]
 * Log: /var/log/portage/cross-avr-gcc-stage2.log
 * Emerging cross-gcc-stage2 ...                                            [ ok ]

If this end with no problem then you can start compiling code for AVR platform using "avr-gcc".

Just for reference i included name and version installed by crossdev tool:

# eix -c cross-avr/*
[I] cross-avr/avr-libc [1] (1.8.0[?]@03.08.2012): C library for Atmel AVR microcontrollers
[I] cross-avr/binutils [1] (2.22.90[?]@03.08.2012): Tools necessary to build programs
[I] cross-avr/gcc [1] (4.6.3(4.6)[?]@03.08.2012): The GNU Compiler Collection
[N] cross-avr/gdb [1] ((~)7.4.1): GNU debugger
[1] /opt/local/portage
#

de-installation of cross compile tools

If you whould like to remove AVR tools then simply enter following command:

crossdev -C avr

If crossdev is no longer required on machine then it can be removed using portage command:

emerge -C crossdev

I don't recommend to remove crossdev if there are still present targets installed using crossdev.

workarounds

Problem with linker 1

 /usr/libexec/gcc/avr/ld: cannot open linker script file ldscripts/avr5.x: No such file or directory 

Fix:

# locate ldscripts/avr5.x
/usr/lib64/binutils/avr/2.22.90/ldscripts/avr5.x

# ln -s /usr/lib/binutils/avr/2.22.90/ldscripts /usr/avr/lib/ldscripts

Problem with linker 2

/usr/libexec/gcc/avr/ld: cannot find crtm328p.o: No such file or directory 

Fix:

# locate crtm328p.o
/usr/avr/lib/avr5/crtm328p.o

# ln -s /usr/avr/lib/avr5/crtm328p.o /usr/avr/lib/crtm328p.o