Re: mm question

From: Alan Cox (
Date: Mon Dec 10 2001 - 12:25:09 EST

> "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.

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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:18 EST