Date: Tue, 1 Jul 2003 11:29:45 +0200 From: Bernd Walter <ticso@cicely12.cicely.de> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: freebsd-arch@freebsd.org Subject: Re: API change for bus_dma Message-ID: <20030701092944.GE90081@cicely12.cicely.de> In-Reply-To: <16128.17218.973911.980939@grasshopper.cs.duke.edu> References: <3EF3C12F.9060303@btc.adaptec.com> <16124.39930.142492.356163@grasshopper.cs.duke.edu> <3EFC9F2D.6020908@btc.adaptec.com> <16124.43999.333761.397624@grasshopper.cs.duke.edu> <3EFCAC7A.6060305@btc.adaptec.com> <16124.45051.919899.414795@grasshopper.cs.duke.edu> <3EFD4755.49BAF150@mindspring.com> <16128.17218.973911.980939@grasshopper.cs.duke.edu>
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On Mon, Jun 30, 2003 at 10:03:46AM -0400, Andrew Gallatin wrote: > The idea is that I want to establish a mapping that can be used many > times without any driver or kernel attention. I don't want to do > anything in terms of a system call, or interrupt, etc, to sync the > cache with the state of the DMA'ed page before a DMA read or after a DMA > write. > > For example, scatter gather mapping on alphas (if FreeBSD supported it > for PCI devices) would be fine with me since its cache-coherent and > doesn't require any ddi_dma_sync() operations. What makes you shure about alpha dma to be cache-coherent? I'm not shure that the current implementation of _bus_dmamap_sync() without barriers is correct. -- B.Walter BWCT http://www.bwct.de ticso@bwct.de info@bwct.de
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