Question

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The problem is that there is a NVidia driver for Linux, compiled wth GCC 4.5. The kernel is compiled with GCC 4.6. Well, the stuff doesn’t work because of the version number difference between GCCs. (the installer says the driver won’t work – for details please visit the link above)

Could one disguise a binary compiled with GCC 4.5 to a binary compiled with GCC 4.6? If it is possible, under what circumstances would it work well?

Answer 1

Your problem is called ABI: Application Binary Interface. This is a set of rules (among others) how functions in a piece of code get their arguments (ordering, padding of types on the stack), naming of the function so the linker can resolve symbols and padding/alignment of fields in structures.

GCC tries to keep the ABI stable between compiler versions but that’s not always possible.

For example, GCC 4.4 fixed a bug in packed bit-fields which means that old/new code can’t read structures using this feature properly anymore. If you would mix versions before and after 4.4, data corruption would occur without any crashes.

There is no indication in the 4.6 release notes that the ABI was changed but that’s something which the Linux kernel can’t know – it just reads the compiler version used to compile the code and if the first two numbers change, it assumes that running the code isn’t safe.

There are two solutions:

1. You can compile the Nvidia driver with the same compiler as the kernel. This is strongly recommended

2. You can patch the version string in the binary. This will trick the kernel into loading the module but at the risk of causing data corruption to internal data structures.