Date: Wed, 07 Dec 2005 11:07:28 -0700 From: Scott Long <scottl@samsco.org> To: "M. Warner Losh" <imp@bsdimp.com> Cc: darren.pilgrim@bitfreak.org, current@freebsd.org Subject: Re: can someone explain...[ PCI interrupts] Message-ID: <439724E0.3020102@samsco.org> In-Reply-To: <20051207.105722.60788677.imp@bsdimp.com> References: <018e01c5fafe$c9154a20$642a15ac@smiley> <20051207.105722.60788677.imp@bsdimp.com>
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M. Warner Losh wrote: > In message: <018e01c5fafe$c9154a20$642a15ac@smiley> > "Darren Pilgrim" <darren.pilgrim@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. Scott
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