Support using the "extra stack" for all 16bit irq entry points.

Using the internal stack reduces the amount of space that SeaBIOS uses
on the caller's stack.  This is known to help some very old operating
systems (like DOS 1.0).  However, there is a possibility that this
will break any operating systems that calls a legacy 16bit irq in
16bit protected mode (no OSes have yet to be identified as doing
this), so make the ability config dependent.

Signed-off-by: Kevin O'Connor <>
2 files changed