Re: pgd/pmd/pte and x86 kernel virtual addresses

[Timur Tabi <ttabi@interactivesi.com>]

** Reply to message from "Benjamin C.R. LaHaise" <blah@kvack.org> on Thu, 24
Aug 2000 19:43:41 -0400 (EDT)


> >  Basically, what I'm
> > trying to do is find the pte for a given physical page.  That is, I'm looking
> > for a function that looks like this:
> > 
> > pte_t *find_pte(mem_map_t *mm);
> > 
> > Given a pointer to a mem_map_t, it returns the pointer to the pte_t for that
> > physical page.  Is there such a function?  I've found things like this:
> 
> There is no such function, and there cannot be for kernel addresses
> since on most x86s, the kernel makes use of 4MB pages to map chunks of
> memory.  If you're looking for the user addresses associated with a
> physical page, there are several ways of doing so, but none of them are
> implemented in the current kernel.

I thought that memory that's not allocated by a user process (i.e. allocated by
a driver that calls get_free_pages) doesn't have a user address.  Is that wrong?

> 
> Why do you need this/what are you trying to do?

What I'm trying to do is allocate some memory via get_free_pages, and then mark
that memory as uncacheable.


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Timur Tabi - ttabi@interactivesi.com
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