Messages in this thread | | | Date | Wed, 11 Jun 2008 11:16:49 -0400 (EDT) | From | Alan Stern <> | Subject | Re: [S] Re: [linux-uwb] packet size problem |
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On Wed, 11 Jun 2008, Jens Axboe wrote:
> > Jens, this is a question for you. How come we're getting an SG element > > whose lenth is 3584 when the request_queue's dma_alignment mask is set > > to 1023? Is dma_alignment not the right parameter to set? > > dma_alignment mask is the buffer address alignment, so they are not > completely the same.
Well then, put it this way: We don't care particularly about the address alignment as such, but we do need the buffer length to be a multiple of 1024 for all but the last element in the SG list. Is there a better way to accomplish this?
> But it does sound odd, since you would then be > spanning two pages for that sg element. Is this before or after dma > mapping the sg table?
Both.
Alan Stern
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