Re: [seL4] Userland components in Ring 1/2 (where kernel is in ring 0) to provide protection from less trusted components

Hello

I was wondering if it makes sense for someone building a system on seL4 to run certain drivers or other critical components in a more privileged environment, but still outside the kernel. Does using a different CPU mode in this context make sense? My hunch is that the case is no, because x86

No, it does not. You may want to run software at the lowest privilege it can run and microkernel environments can effectively work at the lowest privilege ring. What problem do you want to solve?

has those extra rings, but ARM only has two modes, Supervisor/System and User mode, which would make it hard to provide any mechanism for the kernel to manage privileged components, because of the differences between platforms.

-- Dr.-Eng. V. A. Sartakov