How do I build an app for an old linux distribution, and avoid the FATAL: kernel too old error?

Question

I distribute a statically linked binary version of my application on linux. However, on systems with the 2.4 kernel, I get a segfault on startup, and the message: "FATAL: kernel too old."

How can I easily get a version up and running with a 2.4 kernel? Some of the libraries I need aren't even available on old linux distributions circa 2003. Is there an apt-get install or something that will allow me to easily target older kernels?

Jordison

Answer 1

The easiest way is to simply install VirtualBox (or something similar, e.g. VMWare),Install CentOS 3 or any suitable old distro with a 2.4 kernel and build/test your app on that.

Since you're getting a "kernel too old", chances are you're relying on some features not present in 2.4 kernels so you'll have to trace down and rework that. The error might simply be caused by linking statically to glibc, you could try linking to glibc dynamically and all your other libs statically, though to be backwards compatible you'd have to build your app on an old glibv system. Using the lsb tools to build could help too

Savior

LSB wasted a lot of time and didn't work as advertised. The best solution I could come up with is to install different Linuxes on several VMs. (I have to build the newer libraries I use from source for the old ones) Currently I use Ubuntu 8.10, and RedHat 4. Things built on those two can run on the majority of platforms. – Jordison

Answer 2

For my use case, I can't statically link my supporting libraries. Also, current Linux distributions seem to make this difficult to accomplish for certain situations. But I needed my application binaries to run on 10-year old Linux systems.

I also didn't want to limit myself to an ancient 10-year old C/C++ compiler. I also found that the hardware I needed to use prevented me from installing a 10 year old Linux distribution for some reason.

So, I did this:

1. Installed docker.
2. Within a docker instance, install a 10-year old Linux system (I used Debian's Lenny distribution). This has the added advantage of making this build system available to any other machine that can run docker.
3. Within the docker instance, build the current GNU compilers (8.3.0 when I did this).

This gave me a modern compiler that compiled binaries that would run on very old Linux systems. I did this for both 32-bit and 64-bit processors.

From there, I created a series of scripts that allowed me to use the docker-contained cross-compiler to build all my supporting libraries. I made sure to set the rpath to my compiled binaries to a path relative to my binaries (using -Wl,-rpath,$ORIGIN/../lib), and a built a script to retrieve any supporting libraries from the compiler, using g++ -print-search-dirs to get the paths, ldd to get the supporting libraries I needed from my binaries, and some aggressive bash scripting to find the supporting libraries existing within the search-dirs from g++, dropping these libs into the rpath I set up.

From there, I package my binary accordingly, with all supporting libs.

Yeah, this is somewhat painful, but it results in a fully functioning binary capable of working on ridiculously old linux systems without having to install different Linux distributions on multiple virtual machines.

I tried creating a proper cross-compiler (native to the current Linux distribution hosting my docker images), but found it too difficult to work with, even with the best tools I could find to help me. Compiling the compiler within a docker image took far less of my time, and worked rather smoothly.

Sadism