My Debian 7 armel embedded system currently has g++ 4.6, and I'd like to upgrade to g++ 4.9 to use new C++11 features. How do I do that?
My current sources.list contents is:
deb http://security.debian.org/ wheezy/updates main
deb-src http://security.debian.org/ wheezy/updates main
deb http://ftp.us.debian.org/debian wheezy main non-free
deb-src http://ftp.us.debian.org/debian wheezy main non-free
A simple apt-get install of the package does not work:
root@arm:~# apt-get install g++-4.9
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package g++-4.9
E: Couldn't find any package by regex 'g++-4.9'
Another workaround could be to install the g++ 4.9 packages from "Jessie", according to this blog post. Briefly, you would have to tell APT to use the Jessie repos while you are installing the new G++. First bring the current Wheezy up-to-date:
sudo apt-get update
sudo apt-get upgrade
Then do a backup :-) and edit /etc/apt/sources.list so that you replace the string "wheezy" with "jessie":
sudo cp /etc/apt/sources.list /etc/apt/sources.list.WHEEZY
sudo vi /etc/apt/sources.list
Now update the package list and install the 4.9 version of GCC/G++:
sudo apt-get update
sudo apt-get install gcc-4.9 g++-4.9
After this revert to the "original" package list:
sudo cp /etc/apt/sources.list.WHEEZY /etc/apt/sources.list
sudo apt-get update
This leaves the original GCC,G++ in place. If you wish to compile with the 4.9 version, then either set the CC and CXX env vars accordingly or invoke the compilers as gcc-4.9 or g++-4.9 explicitly.
Probably-required: packaging-dev, ubuntu-dev-tools
Set up pbuilder
(this lets you build a package in a chroot without polluting your system with build-dependency packages)
sudo pbuilder create
if you want to build for a specific distribution, (pbuilder uses the build system release in a chroot) you can use pbuilder-dist [precise/oneric/trusy/etc...] create
Get debian source
pull-debian-source gcc-4.9 [4.9.0-6]
specific debian revision is optional, but can be useful if you want to pull experimental/unstable/testing/stable revisions
you can also pull from specific ubuntu distros by adding them to sources.list as a deb-src and using sudo apt-get src
Build Package
sudo pbuilder build gcc-4.9_4.9.0-6.dsc
In the files downloaded there is a .dsc file, for the most recent gcc it is gcc-4.9_4.9.0-6.dsc which is a package descriptor file. .orig.tar.[gz/xz] is the source tarball.
Create local Apt-repository
mkdir /convenient/place/for/repo
cp /var/cache/pbuilder/result/* /path/to/repo
cd /path/to/repo
apt-ftp archive packages . > Packages
sudo echo "deb [trusted=yes] file:/local/repo/Packages ./" > /etc/apt/sources.list.d/gcc-repo.list`
Note you can also do this step with .debs downloaded from anywhere (skip step 1-3)
Install
apt-get update; apt-get install gcc-4.9 g++-4.9
Instead of using the jessie packages, it would be better to check to see if it's been back-ported to wheezy. Add this to your /etc/apt/sources.list:
deb http://http.debian.net/debian wheezy-backports main
and do an apt-get update and see if you can install it then.
There is a gcc-4.9-backport now.
sudo apt-get update && sudo apt-get install gcc-4.9-backport
