Messages in this thread | | | Subject | Re: User switchable HW mappings & cie | From | Benjamin Herrenschmidt <> | Date | Tue, 10 Oct 2006 07:03:49 +1000 |
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On Mon, 2006-10-09 at 20:36 +0200, Ingo Oeser wrote: > Hi all, > > On Monday, 9. October 2006 13:51, Benjamin Herrenschmidt wrote: > > > One problem that occurs is that the rule for ptes with non-backing > > > struct pages > > > Which I think was introduced in 2.6.16: > > > > > > pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) > > > > > > cannot be honored, at least not with the DRM memory manager, since the > > > graphics object will be associated with a vma and not the underlying > > > physical address. User space will have vma->vm_pgoff as a handle to the > > > object, which may move around in graphics memory. > > > > That's a problem with VM_PFNMAP set indeed. get_user_pages() is a > > non-issue with VM_IO set too but I'm not sure about other code path that > > might try to hit here... though I think we don't hit that if MAP_SHARED, > > Nick ? > > Istn't this just a non-linear PFN mapping, you are describing here? > > Nick: > Cant your new fault consolidation code handle that? > AFAICS your new .fault handler just gets the > vma and pgoff and install the matching PTE via install_THINGIE() > or vm_insert_THINGIE() > > Or do I miss sth. here?
It is somewhat yes.
Ben.
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