bios: stub calls interrupt number; simplified bios.ha main interface

Instead of having the bios.call stub calling a function, make it directly call an interrupt that is
changed dynamically by modifying the code at runtime.
Simplify the bios.ha interface and document it.

Next up: implementing a high level drive interface for the BIOS using BIOS interrupts

1 files changed, 2 insertions, 0 deletions

diff --git a/rt/hare.sc b/rt/hare.sc
index 0cb9c02..3de964c 100644
--- a/rt/hare.sc
+++ b/rt/hare.sc
@@ -20,6 +20,8 @@ SECTIONS {
 	. += 4096;
 	_p1 = .;
 	. += 4096;
+	_ws = .;
+	. += 512;
 
 	. = 0x7c00;
         stack_top = .;