🚀 go-pugleaf

In article <71689@microsoft.UUCP> donh@microsoft.UUCP (Don HACHERL) writes:
}In article <1991Mar29.155840.2626@netcom.COM> resnicks@netcom.COM (Steve Resnick) writes:
}>Everything works great until I run this under OS/2 rather than MS DOS.
}>OS/2 will not let me clear interrupts while changing SS:SP.  My question:
}>Is it necessary to disable interrupts while switching stacks in protected 
}
}Not only do you not need an IOPL segment, you don't even need to
}disable interrupts, under DOS or OS/2, because the chip will do it for
}you.  To quote from my handy Intel refernce manual "A MOV into SS
}instruction inhibits all interrupts until after the execution of the
}next instruction (which is presumably a MOV into SP instruction)."

The reason why everybody disables interrupts during a stack switch is that
the early 8088s had a microcode bug which caused interrupts to remain
enabled after a MOV into SS.  If your code can't run on an 8088/8086, you
won't need the CLI.
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