[$] User-space interrupts

The term "interrupt" brings to mind a signal that originates in thehardware and which is handled in the kernel; even software interrupts are akernel concept. But there is, it seems, a use case for enabling user-spaceprocesses to send interrupts directly to each other. An upcoming Intelprocessor generation includes support for this capability; at the 2021 Linux Plumbers Conference,Sohil Mehta ran aKernel-Summit session on how Linux might support that feature.