> batch all syscalls by default Switching from user mode to kernel mode and back (a “context switch”) is expensive. Traditionally, OSes did that on every syste

> batch all syscalls by default Switching from user mode to kernel mode and back (a “context switch”) is expensive. Traditionally, OSes did that on every system call. You can go faster if you have some mechanism for sending more than one system call in a single context switch. > security context Basically, what is a program allowed to do? Traditionally, Unixy (nowadays, Linux and friends) limit this based on just the current user, assuming that the user trusts every program they run. But nowadays you often don’t trust every program you run, and want it to be in its own limited sandbox. > limit […] root Most OSes have a super user that can do anything (pid 0 on Unixy things; Windows is more complex but still has them). They’re saying to not have that, instead make the super user only capable of stopping problematic things, not creating new things. This is the one I’m more ambivalent on. At some point something has to set up the whole system, and the thing that kicks that off is going to look pretty superuser-like to me.