Qubes is an open source operating system designed to provide strong security for desktop computing.
Qubes OS vs grsecurity opinions
While there is none replacement for grsecurity, at least qubes can separate things while grsecurity can prevent at kernel level which is the highest. Qubes OS security is based upon consciousness, the weakest link of the security where human is the factor. Qubes depends on several templates distros, it can't stop the attack like what grsecurity does but can separate which application vm (appvm) you should use, instead of mix everything together in one place.
AppArmor is an effective and easy-to-use Linux application security system. AppArmor proactively protects the operating system and applications from external or internal threats, even zero-day attacks, by enforcing good behavior and preventing even unknown application flaws from...
The CLIP OS project is an open source project maintained by the ANSSI (National Cybersecurity Agency of France) that aims to build a secure, multi-level operating system, based on the Linux kernel and a lot of free and open source software.