From owner-freebsd-arch  Tue Feb 19 21:40:12 2002
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Date: Tue, 19 Feb 2002 21:38:14 -0800 (PST)
From: Julian Elischer <julian@elischer.org>
To: "M. Warner Losh" <imp@village.org>
Cc: mike.varga@cavium.com, msmith@FreeBSD.ORG,
	freebsd-arch@FreeBSD.ORG
Subject: Re: reverse vtophys() 
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Mike,

How do you know the page is locked in memory?
but more importantly, how do you know it is only mapped to a single
address?

we ar moving toward keeping a lot of pages unmapped and for DMA devices
the need never be mapped for IO.
they need onlybe mapped when copying data to serspace or when mmapping
them.

We'd need to know a much more specific reason to be able to give you the
answer.


I may have missed some of your posts. sorry if you already gave this
information.

Julian

On Tue, 19 Feb 2002, M. Warner Losh wrote:

> In message: <004f01c1b96b$a37d1f50$b210a8c0@netscreen5>
>             "mike varga" <mike.varga@cavium.com> writes:
> : The concept is valid in Linux,
> : there is a function that does
> : what I am asking.
> : bus_to_virtual().
> : 
> : The page is locked 
> : in memory. 
> : Therefor there is one valid page
> : backed by the physical 
> : address that corresponds
> : to the virtual address that 
> : I am interested in retrieving?
> 
> If you have used the bus_space functions, you could use
> rman_get_virtual(r), where r is a struct resource * that you got back
> from bus_alloc_resource().
> 
> Warner
> 
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