Signals

[edwardwawrzynek]

We need some kind of signal mechanism, or at least some way to do Ctrl+c and kill.

[edwardwawrzynek]

Probably a second context + stack page is needed, and we need processes handling signals to be able to do syscalls.

Additionally, a signal queue should be implemented so that signals can be buffered. If a signal handler triggers a hardware exception, we can probably just immediately call the handler for that exception, otherwise queue it.

Signal handling should probably just be a part of regularly schedule process execution, and just set up the special signal stack frame so that returning from a signal handler calls a special syscall that ends signal handling.

Signal handlers should not be able to cause the whole system to hang or get screwed up.

Stack page allocation needs to be moved from memory context into execution context records, or at least kept somewhere in execution context records in the process table.