How to install gcc 4.9 arm cross compiler on debian stretch

Question

Debian "stretch" has built-in cross compilers for gcc versions 5 and 6, but apparently only includes the native architecture in its gcc-4.x packages. Unfortunately I need to compile software that depends on older Linux kernel headers that fail to build with gcc versions later than 4.x (they end up trying to include a file include/compiler-gcc<major-version>.h that doesn't exist for later version numbers), so these are no use to me.

I tried using the "embedian" repository, but it only had version branches for "wheezy", "jessie" and "unstable", so assuming "unstable" was an out-of-date reference to stretch I tried that, but I don't seem to be able to persuade it to install anything useful. The error I get is:

The following packages have unmet dependencies:
 gcc-4.9-arm-linux-gnueabihf : Depends: cpp-4.9-arm-linux-gnueabihf (= 4.9.2-16) but it is not going to be installed
                               Depends: libgcc-4.9-dev:armhf (= 4.9.2-16)
                               Depends: libisl13 (>= 0.10) but it is not installable
                               Recommends: libc6-dev:armhf (>= 2.13-5)
E: Unable to correct problems, you have held broken packages.

I believe the first two failed packages are available to be installed, so I could do those manually if necessary, but the third does not seem to exist anywhere I look.

Any suggestions how I can get a working gcc-4.9 (or earlier) cross compiler for arm-linux-gnueabihf on this system?

Answer 1

Emdebian stopped being maintained in November 2014. You might be able to get the packages you've found to work using libisl13 from snapshots.

Otherwise, you can build a cross-compiler using the gcc-4.9 package and possibly dpkg-cross; see README.cross for details. Basically, you need cross-binutils, and the appropriate library packages (the multiarch packages in Jessie or Stretch should do, hopefully without converting them using dpkg-cross); then

apt-get source gcc-4.9
cd gcc-4.9-4.9.4
GCC_TARGET=armhf dpkg-buildpackage -us -uc

The gcc-4.9 packages are part-way through the transition to plain multiarch instead of dpkg-cross, so you might run into some issues. (The transition was completed in the gcc-5 and gcc-6 packages.)