Re: virtual memmap and page_address

[Jesse Barnes <jbarnes@engr.sgi.com>]

On Wednesday, December 15, 2004 9:53 am, Jesse Barnes wrote:
> I've been messing around with some of the drm drivers lately, and in some
> cases they'll call pci_map_single on an address returned from
> page_address(). When virtual memmaps are enabled, page_address will return
> a region 5 pointer.  It looks like all of the ia64 iommu code (swiotlb,
> sba_iommu and sn2's pci_dma) assume that the address passed in is an
> identity mapped address since they use __pa to get the physical address. 
> This is fast, but also incorrect when the routines are handed a region 5
> address.  So we either have to fix our iommu mapping routines or change
> some other assumptions (either about what page_address should return or
> what __va in general means for example).  Turning on WANT_PAGE_VIRTUAL and
> populating page->virtual with an identity mapped address is another option,
> probably less expensive than switching to ia64_tpa in the mapping routines.

Nevermind, obviously I haven't had enough coffee this morning.  page_address 
correctly returns an identity mapped address so my problem lies elsewhere.