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    SubjectRe: [PATCH-2] NMI trap revised (was Re: NMI errors in 2.0.30??) (fwd)
    Date
    > 
    > On Tue, 13 May 1997, Gabriel Paubert wrote:
    >
    > > During the NMI routine all interrupts are masked anyway, and even NMIs are
    > > masked until the CPU executes an IRET instruction. But the problem is
    > > printk...
    >
    > Not true with ix86 processors. To mask non-maskable interrupts you adjust
    > a bit in port 0x61 (I don't have the documentation here). This is the
    > "keyboard" chip which is really a port/uP with built-in ROM. This
    > physically disconnects the NMI line to the processor. I think it is
    > either bit 4 or 5. Anyway non-maskable interrupts are not maskable which
    > means CLI and STI don't affect them. Therefore the INT bit in the flags
    > register (which would be restored from the stack upon an IRET) does not
    > affect it.

    Dick ist right. Hey, after all NMI stands for "Non Maskable Interrupt" ...

    Ralf

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