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In one of my previous posts I have described how to run Gentoo on Android ARM device. Depending on its power your emerges may take either a long time or a longer time. And your device will warm up significantly. But you have already heard of and used FEATURES=”distcc”, right? Here’s how to set-up a cross compilation with a help from an x86 box in a nutshell.

For sake of clarity I will refer to the systems as follows:

• box – your laptop, PC, server, etc. – where distccd will be running to serve the compilation power
• phone – the Android ARM device with FEATURES=”distcc” enabled

First of all – in order to minimize impact on your box system I strongly advise to use a separate chroot incarnation of Gentoo. Therefore – get your latest stage3 archive and unpack it properly into an empty, new directory of your choice:

(box) # mkdir /mnt/arm-crossdev-chroot
(box) # cd /mnt/arm-crossdev-chroot
(box) # wget -q -O /dev/stdout $STAGE3_URL | tar xvfjp -

Set-up your bind mounts for the chroot (/dev, /proc, /usr/portage, optionally /usr/portage/distfiles):

(box) # mount --bind /dev ./dev
(box) # mount --bind /proc ./proc
(box) # mkdir ./usr/portage
(box) # mount --bind /usr/portage ./usr/portage
(box) # # if you need to:
(box) # mount --bind /usr/portage/distfiles ./usr/portage/distfiles

Chroot inside (and stay there) and set-up some sane environment:

(box) # chroot . /bin/bash
(box) # env-update && source /etc/profile
(box) # PS="(crossdev-chroot) $PS1"
(box) # export PS1="(crossdev-chroot) $PS1"
(box) # echo 'PS1="(crossdev-chroot) $PS1"' >> ./etc/profile
(box) # env-update && source /etc/profile
(box) # echo GENTOO_MIRRORS=$YOUR_MIRRORS >> /etc/make.conf

Match your gcc versions on the phone and on the box – just to be safe with well known general distcc guideline.

What you need to do now is to emerge distcc and crossdev:

(box) # emerge -va distcc crossdev

And set up crossdev for ARM like this:

(box) # mkdir /usr/local/portage
(box) # echo 'PORTDIR_OVERLAY="/usr/local/portage"' >> /etc/make.conf
(box) # crossdev -S -P -v -t armv7a-hardfloat-linux-gnueabi

You need to match the CHOST value above to what you have on your phone. Having done all that you should be almost ready. You may now try running distcc in the foreground on the box:

(box) # distccd --verbose --no-detach --log-stderr --allow x.x.x.x/yy --port 11453

If you see it starting up and the compiler seems OK you need to set up the phone – emerge distcc on it locally first and set-up FEATURES in make.conf. Note that this needs to be performed inside your Gentoo chroot of course.:

(phone) # emerge -va distcc
(phone) # echo y.y.y.y:11453 >> /etc/distcc/hosts
(phone) # echo 'FEATURES="distcc"' >> /etc/make.conf

And a final touch recommended by the excellent Gentoo’s guide to distcc cross-compiling (on the phone) – in a nutshell:

(phone) # cd /usr/lib/distcc/bin

Create a wrapper script with the following content:

#!/bin/bash
exec /usr/lib/distcc/bin/armv7a-hardfloat-linux-gnueabi-g${0:$[-2]} "$@"

And name it armv7a-hardfloat-linux-gnueabi-wrapper.

Then chmod it and set-up symlinks:

(phone) # rm c++ g++ gcc cc
(phone) # chmod a+x armv7a-hardfloat-linux-gnueabi-wrapper
(phone) # ln -s armv7a-hardfloat-linux-gnueabi-wrapper cc
(phone) # ln -s armv7a-hardfloat-linux-gnueabi-wrapper gcc
(phone) # ln -s armv7a-hardfloat-linux-gnueabi-wrapper g++
(phone) # ln -s armv7a-hardfloat-linux-gnueabi-wrapper c++

Now you should be all set. Make sure your portage user is set to an uid which is not deprived of network connectivity – see my previous post for details. Now emerge something and watch the output on box generated by foreground distccd:

(phone) # emerge -va vim

Good luck!

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