Re: mm question

Alan Cox (alan@lxorguk.ukuu.org.uk)
Mon, 10 Dec 2001 17:25:09 +0000 (GMT)


> "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
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/