Prep for ARM MMU work
Change the optimisation options to get the release build working
Get the Pi's UART routed through to the IN pipe
KShell is receiving bytes but not correctly. Pipe issue.
The writer is updating the current position to the end of the stream.
The reader needs a separate pointer.
KShell basic input working but still unstable
Newline on end of command
Pipe stuff in KShell
Fix the map iterator
Tweak the debugging issues
Work on the arm context switching to backup the state correctly.

Doesn't work properly as the state doesn't seem to restore correctly.
Vector work
Don't switch to Supervisor mode, stay in System mode.

Stops the stack getting switched which stops the functions returning.
Remove some debugging from interrupt controller
Don't bother to save r14, just r13 (sp)
More debugging for the context switching
Switch back to the old mode rather than assume it's supervisor
Docs