Both ideas have attracted interest, but neither has yet been pushed long or hard enough to make it into the mainline. More recently, Al Viro suggested AT_NO_JUMPS as a way of preventing lookups from venturing outside of the current directory hierarchy or the starting directory’s mount point. David Drysdale posted an O_BENEATH option to openat() in 2014 that would require the eventual target to be underneath the starting directory (as provided to openat()) in the filesystem hierarchy. There have been previous attempts at restricting pathname lookup, but none of them have been merged thus far.
A new patch set from Aleksa Sarai has revived an old idea: provide a set of AT_ flags that can be used to control the scope of a given pathname lookup operation. There are times, though, when it is desirable to reduce that access, usually for reasons of security that has proved to be especially true in many container use cases. System calls like openat() have access to the entire filesystem - or, at least, that part of the filesystem that exists in the current mount namespace and which the caller has the permission to access. New AT_ flags for restricting pathname lookup.If each of those cores exposes multiple interfaces for simultaneous instruction execution, which Intel calls “hyperthreading”, then each of those threads is a CPU. If the processor has multiple cores, each of those cores is a CPU. On a simple, single-core single-processor system, that core is the CPU. Precise to a fault, Wysocki defined his terms: for the purposes of this discussion, a CPU is an entity that can take instructions from memory and execute them at the same time as any other entities in the same system are doing likewise.
The idle loop, one of the kernel subsystems that Wysocki maintains, controls what a CPU does when it has no processes to run. At Kernel Recipes 2018, Rafael Wysocki discussed what CPUs do when they don’t have anything to do, how the kernel handles this, problems inherent in the current strategy, and how his recent rework of the kernel’s idle loop has improved power consumption on systems that aren’t doing anything. It would be reasonable to expect doing nothing to be an easy, simple task for a kernel, but it isn’t.
Longtime Ubuntu/Linux PC vendor System76 has been teasing their efforts around an “open-source computer” and other open-source hardware efforts now that they are in the home stretch of setting up their own US-based manufacturing facility.