HPC @ Uni.lu

High Performance Computing in Luxembourg

FAQ: Why Do I Suddenly Get an "Illegal Instruction" Error?

You might encounter this error when running a tool or software you installed yourself, even though it used to work before.

This can happen if you compiled the software on a newer CPU than the one you’re trying to run it on, and which does not contain the same advanced features.

To solve the issue, one option is to compile the software on a node with the oldest CPU type:

oarsub -p "cputype='xeon-gulftown'"

You can also make sure you always run it on the same CPU type as you installed it on, by specifying the cputype property in your job submission.

You can check CPU types by clicking on a node name in Monika or by filtering in Monika’s OAR properties form on the cputype property.

Currently the following CPU types are defined, corresponding to the different CPU architectures: