Date: Sun, 14 Feb 2010 21:06:50 +0800 From: "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au> To: freebsd-x11@freebsd.org Subject: Re: DRI problems with ati/radeon on stable/7 r203425 [SEC=UNCLASSIFIED] Message-ID: <20100214130650.GB57098@stlux503.dsto.defence.gov.au> In-Reply-To: <20100210150604.GC391@bunrab.catwhisker.org> References: <20100208172654.GA391@bunrab.catwhisker.org> <1265764746.8609.18.camel@balrog.2hip.net> <20100210023558.GV391@bunrab.catwhisker.org> <1265802517.8609.25.camel@balrog.2hip.net> <20100210130642.GA391@bunrab.catwhisker.org> <1265813805.8609.52.camel@balrog.2hip.net> <20100210150604.GC391@bunrab.catwhisker.org>
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0n Wed, Feb 10, 2010 at 07:06:04AM -0800, David Wolfskill wrote:
>Well, I don't know what msi is, so I hadn't tried that.
It stands for Message Signaled Interrupts, and it's a new way for PCI
devices to generate interrupts. Instead of asserting a hardware
signal on an interrupt line, the device does a write (using direct
memory access) to a special address. The chipset sees the write and
generates an interrupt to the CPU.
The benefit ...
Fewer dedicated signal lines on the motherboard == lower cost.
Elimination of shared IRQs. Guaranteed ordering between DMA
operations and the generation of the interrupt.
-Alex
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