Date: Fri, 23 Oct 1998 08:05:14 -0600 From: vanmaren@fast.cs.utah.edu (Kevin Van Maren) To: Etienne.Debruin@KryptoKom.DE, freebsd-hackers@FreeBSD.ORG Subject: Re: Q: bus mastering Message-ID: <199810231405.IAA16725@fast.cs.utah.edu>
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> hi, i paged through the mail list archives but could not find a specific > technical discussion about bus mastering. i would like to implement bus > mastering for a pci device driver. need more info... > > eT This is highly device-dependant. Each bus-master-capable PCI device has its own DMA controller, and they are all programmed in a device-specific manner. It is not at all like ISA, where there is a centralized DMA controller that is used for DMA transfers. As a good start, you can grep for "vtophys" in src/sys/pci/*.c, but a better bet would be to get the programming info for the specific device you are interested in. (Many of the ethernet devices, especially, support scatter-gather DMA). Good luck. Kevin Van Maren To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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