prehistorik2 doesn't work

[stsp]

prehistorik2 doesn't work

[stsp]

Bisect: 785ee04

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@ecm-pushbx This is caused by
your ISR detection trick.
I think prehistoric chains to the
previous IRQ5 handler after doing
EOI. :(
Can you work out the solution?

[stsp]

And in fact this is a very reasonable
thing to do, because bios is not supposed
to know that IRQ5 is from SB16.
So bios only does IRET.
As such, chaining to prev irq5 handler
after doing EOI, is not a bug!
Which means, we added a bug.
Such detection can not be used.

[stsp]

In dosemu2 we do this:

    case 8 ... 0x0f:
      SETIVEC(i, BIOSSEG, EOI_OFF);
      break;

I don't think this is correct.
We only need to set some ints
to EOI_OFF, namely those for
which we have the handlers.
Which would then be
8, 9, 11, 12, 14, 15.

[stsp]

OK, so I removed SS handler and
changed GPF handler to only use
IMR.