The syscall/sysret instructions don't swap stacks. This was bad but
passable until syscalls caused the scheduler to run, and scheduling a
task that paused due to interrupt.
Adding a new (hopefully temporary) syscall interrupt `int 0xee` to allow
me to test syscalls without stack issues before I tackle the
syscall/sysret issue.
Also implemented a basic `pause` syscall that causes the calling process
to become unready. Because nothing can wake a process yet, it never
returns.
- Scheduler now has multiple linked_lists of processes at different
priorities
- Process structure improvements
- scheduler::tick() and scheduler::schedule() separation
* It looks like UEFI enables SSE, so we need to tell clang -mno-sse for
now to not use XMM* until we're ready to save them.
* SYSCALL is working from ring3 tasks, calling console printf!
* Implement MSI style interrupts
* Move interrupt handling to device_manager for IRQs
* Give device_manager the ability to allocate IRQs
* Move achi::port to an interrupt-based scheme
