Date: Tue, 18 Feb 2003 09:35:48 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Peter Wemm <peter@wemm.org> Cc: Marcel Moolenaar <marcel@xcllnt.net>, cvs-src@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/alpha machdep.c Message-ID: <15954.17604.453276.246271@grasshopper.cs.duke.edu> In-Reply-To: <20030217215943.602032A89E@canning.wemm.org> References: <15953.15467.687489.517344@grasshopper.cs.duke.edu> <20030217215943.602032A89E@canning.wemm.org>
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Peter Wemm writes:
>
> It depends on the tag declarations. If you tell busdma that the device
> can address 64 bit, then it just does. Its up to your driver to deal with
> DAC or larger address pointers or whatever. I seem to recall that many
Sure. Already do. But we (FreeBSD) don't seem to declare a
BUS_SPACE_MAX{ADDR,SIZE}_64BIT yet.
> of the ahc family have space in the descriptors for 39 bit addressing.
> The ahc driver gives an example of how to configure and use this.
Ugh. Talk about off by one. Most alpha chipsets require bit 40 be
set when using 64-bit DMA addresses. (the one I'm working on uses
bit 49).
Drew
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