Date: Mon, 24 Feb 2003 21:15:10 +0100 (CET) From: Harti Brandt <brandt@fokus.fraunhofer.de> To: Hiten Pandya <hiten@unixdaemons.com> Cc: Dag-Erling Smorgrav <des@ofug.org>, current@FreeBSD.ORG, tlambert2@mindspring.com Subject: Re: busdma documentation Message-ID: <20030224210227.I54577@beagle.fokus.gmd.de> In-Reply-To: <20030224143225.GA74746@unixdaemons.com> References: <20030224143225.GA74746@unixdaemons.com>
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On Mon, 24 Feb 2003, Hiten Pandya wrote: HP>Harti Brandt (Mon, Feb 24, 2003 at 11:41:57AM +0100) wrote: HP>> On Mon, 24 Feb 2003, Dag-Erling Smorgrav wrote: HP>> HP>> DS>is there any? if so, where? HP>> HP>> Hiten Pandya was/is working on this. Last time I had a look it had not HP>> much moved from NetBSD towards FreeBSD. Don't know about the current HP>> state: HP>> HP>> [1] http://www.unixdaemons.com/~hiten/work/misc/bus_dma.9.txt HP>> [2] http://www.unixdaemons.com/~hiten/work/misc/bus_dma.9.patch HP> HP>I am still working on it, and the URLs provided above are old. The new HP>URL to busdma documentation stuff, is: HP> HP> http://www.unixdaemons.com/~hiten/work/busdma/ HP> HP>There are some issues I am sorting out, and you can check my progress HP>with the TODO list in the directory. It will be finished sometime this HP>week as I was busy last week with other things, like school etc. Just a comment: the alignment argument to bus_dma_tag_create is unfortunately not used in the way you describe. It is ignored, except when bus_dmamem_alloc calls contigmalloc on all architectures. And it is used if it is larger than an IOPAGE on sparc64. If you need a smaller aligment, you must either fiddle around with a larger memory allocation (if you are going to call bus_dmamem_alloc) or rely on the undocumented fact, that aligning the virtual address also aligns the physical address (for small alignments). The latter is true at least for all architectures that have no IOMMU and for sparc. harti -- harti brandt, http://www.fokus.gmd.de/research/cc/cats/employees/hartmut.brandt/private brandt@fokus.fraunhofer.de, harti@freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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