Date: Thu, 02 Aug 2001 22:25:04 -0700 From: Mike Smith <msmith@freebsd.org> To: tlambert2@mindspring.com Cc: Charles Randall <crandall@matchlogic.com>, Rik van Riel <riel@conectiva.com.br>, craig <craiglei@pasia.com.cn>, freebsd-hackers@FreeBSD.ORG Subject: Re: How to visit physical memory above 4G? Message-ID: <200108030525.f735P4C02496@mass.dis.org> In-Reply-To: Your message of "Thu, 02 Aug 2001 22:15:39 PDT." <3B6A337B.5A81232B@mindspring.com>
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> The costs involved in doing DMA to/from the memory region
> above 4G will be incredible, unless the address space is
> both exported, and known, to the PCI bus; even then, it
> could only work for 64 bit cards, since 32 bith cards will
> only be able to address the first 4G of physical memory.
Actually, most server-class hardware these days will have no trouble with
DMA above 4GB; even the 32-bit devices support DAC.
--
... every activity meets with opposition, everyone who acts has his
rivals and unfortunately opponents also. But not because people want
to be opponents, rather because the tasks and relationships force
people to take different points of view. [Dr. Fritz Todt]
V I C T O R Y N O T V E N G E A N C E
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