Ever since I started working on QEMU, a small directory called tests/tcg has been in a perpetually broken state. It contains tests that exercise QEMU’s ability to work across architectures using the power of the Tiny Code Generator. However as these tests needed to be compiled for the guest architectures and not the host architecture—this is known as cross-compiling—most developers never ran them. As the tests were hardly ever built inevitably a certain amount of bit-rot set in.