On Wednesday 07 December 2005 01:07 pm, Scott Long wrote: > 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. > > > > Warner > > 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. That's not for delivery, that's for how the APIC interprets the signals you see. See my earlier e-mail why misprogramming the APIC would hose things. MSI is a whole different ball of wax entirely in that regard. -- John Baldwin <jhb_at_FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.orgReceived on Wed Dec 07 2005 - 19:41:55 UTC
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