Linux Kernel Module Cheat

11.4.1. FATAL: kernel too old failure in userland simulation

glibc has a check for kernel version, likely obtained from the uname syscall, and if the kernel is not new enough, it quits.

Both gem5 and QEMU however allow setting the reported uname version from the command line for User mode simulation, which we do to always match our toolchain.

QEMU by default copies the host uname value, but we always override it in our scripts.

Determining the right number to use for the kernel version is of course highly non-trivial and would require an extensive userland test suite, which most emulators don’t have.

./run --arch aarch64 --kernel-version 4.18 --userland userland/posix/uname.c

Source: userland/posix/uname.c.

The QEMU source that does this is at: https://github.com/qemu/qemu/blob/v3.1.0/linux-user/syscall.c#L8931 The default ID is just hardcoded on the source.

Bibliography:

https://stackoverflow.com/questions/48959349/how-to-solve-fatal-kernel-too-old-when-running-gem5-in-syscall-emulation-se-m
https://stackoverflow.com/questions/53085048/how-to-compile-and-run-an-executable-in-gem5-syscall-emulation-mode-with-se-py/53085049#53085049
https://gem5-review.googlesource.com/c/public/gem5/+/15855