Subject: Re: mm question
To: volodya@mindspring.com
Date: Mon, 10 Dec 2001 17:25:09 +0000 (GMT)
Cc: alan@lxorguk.ukuu.org.uk (Alan Cox), linux-kernel@vger.kernel.org
In-Reply-To: <Pine.LNX.4.20.0112101041020.17406-100000@node2.localnet.net> from "volodya@mindspring.com" at Dec 10, 2001 11:05:22 AM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Sender: linux-kernel-owner@vger.kernel.org

> "AGP addressable" memory which is ~64meg less than the total amount on my
> machine. However, looking around in AGP driver or AGP specs does not seem
> to indicate any restriction of the sort and, moreover, I do not need AGP
> for this DMA transfer (it is PCI only).

Can the transfer go to pages mapped into the AGP gart, using their gart
side mapping ?

> Better than giving up.. Unfortunately looking around in
> linux/Documentation and drivers did not yield much in terms of
> explanation. I know I can use mem_map_reserve to reserve a page but I
> don't know how to get page struct from a physical address nor which lock
> to use when messing with this.

You have to grab them at boot time via bootmem to get them in a range of
your choice. Otherwise you can use

	get_free_page		-	grab a page
	virt_to_page		-	page struct of page
	virt_to_bus		-	bus addr of page

virt_to_bus isnt portable because real world pci bus mapping on non x86 is
deeply murky and mysterious. But you probably want to worry about that
after it works.

Alan
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