>> someone said EMM386 is incompatible with HLT instruction?
MD> EMM386 uses the HLT instruction for its own purposes, but it
MD> does a check if the HLT is coming from itself or externally.
MD> Other than that, it looks like HLT causes the expected HLT
MD> behavior when the exception handler is triggered (since HLT is V86
MD> illegal). Tom Ehlert would probably know the most about this if
MD> you need more info, since I believe it's his coding for the HLT
MD> mechanism in EMM386.
HLT is a protected instruction, which causes an illegal opcode
interrupt in VM86 mode - it's up to the handler to do whatever it
likes. BTW: mov bx,[ffff] is an invalid instruction also on any 386
It's not my coding (or whatever michael left of it, I didn't check),
but the original implementation by harald albrecht used it as a way to
cummunicate from V86 mode to PM mode.
AFAIR, the emulated behaviour is similar to
if (opcode == HLT)
if (source is in EMM386 V86 device)
{
do something clever as commanded by V86 part
}
else
{
NOP
}
I may be wrong, but it probably never does HLT.
tom
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