Setting up the build environment 1.7

From Alpine Linux

Quick note on how to set up a build environment.

In this document the build environment will be created in /opt/alpine/1.7. You can ofcourse place it anywhere you have space. You will need a few Gigabytes to have enough space for kernel cmpiling and storing all the binary packages and iso image.

Requirements

You need a 2.6 kernel to use the chroot build environment.

  • Note: Make sure your running kernel supports 16bit UIDs for backward compatibility. uCLibc needs them. Check it with:
zcat /proc/config.gz | grep CONFIG_UID16

or if you dont have /proc/config.gz: 

grep CONFIG_UID16 /boot/config-`uname -r`

You should se something like: 

CONFIG_UID16=y

Step-by-step

All packages are downloaded from http://dev.alpinelinux.org/alpine/v1.7

  • Download latest buildroot package from [1] and unpack it in /opt/alpine, using the --preserve-permissions option and create a symblink named 1.7 for the development branch.
sudo mkdir -p /opt/alpine
cd /opt/alpine
wget -q -O - http://dev.alpinelinux.org/alpine/v1.7/buildroot/alpine-buildroot-latest.tar.bz2\
    | sudo tar -vjxp
sudo ln -s alpine-buildroot-1.7.6 1.7


  • Copy your DNS configuration to the build environment and mount proc.
sudo cp /etc/resolv.conf /opt/alpine/1.7/etc/
sudo mount -t proc proc /opt/alpine/1.7/proc
sudo mount -o bind /dev /opt/alpine/1.7/dev
  • Enter the chroot and change the prompt to reflect your chroot environment
sudo chroot /opt/alpine/1.7 /bin/bash --login
export PS1="(chroot) $PS1"

Now we are in the build environment chroot. 

cd /usr
wget -q -O - http://mirror.gentoo.se/snapshots/portage-latest.tar.bz2 portage-latest.tar.bz2 | tar -vjx
  • Check out the alpine-portage overlay from svn.
svn co svn://svn.alpinelinux.org/alpine-portage/trunk /usr/alpine-portage
  • Download all the tbz2 packages into the var/cache/packages directory. This is probably easiest with rsync.
rsync -rauv rsync://rsync.alpinelinux.org/alpine/v1.7/tbz2/* /var/cache/packages/
  • Check out the alpine-builder scripts in usr/src/
svn co svn://svn.alpinelinux.org/alpine-builder/trunk /usr/src/alpine
  • Configure portage to use the config from alpine-builder.
rm -r /etc/make.conf /etc/portage
ln -s /usr/src/alpine/buildroot/etc/make.conf /etc
ln -s /usr/src/alpine/buildroot/etc/portage /etc
  • Update the portage tree (this takes some time first time you do it)
emerge --sync
  • Install the kernel sources, using the downloaded tbz2.
This step is no longer neccessary as this is done automatically within the build script.
  • Make sure that /usr/src/linux points to your kernel version: (the below mentioned steps are optional as this is done automatically by the alpine build process - in case your build breaks, check if the linux source link exists)
cd /usr/src
rm -f linux
ln -s linux-2.6.20-hardened-r10 linux
  • Build the alpine images (iso, usb, flash, etc.)
cd /usr/src/alpine
make

If you get failures while building kernel drivers then you can workaround that by commenting out the specific in /usr/src/alpine/kernel/generic/drivers.

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