can someone explain...[ PCI interrupts]
scottl at samsco.org
Wed Dec 7 10:07:40 PST 2005
M. Warner Losh wrote:
> In message: <018e01c5fafe$c9154a20$642a15ac at smiley>
> "Darren Pilgrim" <darren.pilgrim at bitfreak.org> writes:
> : From: John Baldwin
> : >
> : > The reason [for masking interrupts] is that PCI interrupts are level
> : > triggered, so they won't "shut up" until the ISR has run and pacified
> : > the PCI device.
> : But PCI interrupts can be programmed either level- or edge-triggered, so
> : wouldn't programming to edge-triggered interrupts solve the "they won't shut
> : up" issue?
> PCI interrupts are level. There's no way to program them otherwise.
While electrically they are level, the APIC can be programmed to pass
them on either level or edge. Once you get into MSI, the distinction
becomes very muddy.
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