GetScatterGatherList will coallesce contiguous SG list entries

GregH asked me an interesting question at WinHEC today – one for which I didn’t immediately know the answer.  He was wondering whether the new DMA DDIs (Get|PutScatterGatherList) would return a single SG entry for each page, or whether they would coallesce physically contiguous pages into a single entry. The answer is that the coallescing…

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What is DMA (Part 9): I/O MMUs and why you’ll wish you’d used the DMA DDI in 3 or 4 years

Perhaps you’ve read through all of my posts about DMA and still think that using the DMA DDIs is optional.  After all you’ve built a 64-bit card, and you’re not using DAC so you don’t have to worry about busses being downgraded on you (or maybe you don’t believe in the boogyman either).  Sure someone…

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What is DMA (Part 8) – BuildScatterGatherList

Since i’m on vacation next week, i thought i’d tackle something light this week. Last time i talked about GetScatterGatherList and PutScatterGatherList and how much better they are than the older method of doing DMA.  But as much as I like these two functions, they have one major problem that hit us while we were…

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