Re: [RFC] Changing VM_PFNMAP assumptions and rules

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Mon, 2007-11-12 at 15:53 -0800, Jared Hulbert wrote:

> > > I have a page that is at a hardware level read-only.  What kind of
> > > rules can that page live under?  More importantly these PFN's get
> > > mapped in with a call to ioremap() in the mtd drivers.  So once I
> > > figure out how to SPARSE_MEM, hotplug these pages in I've got to
> hack
> > > the MTD to work with real pages.  Or something like that.  I'm not
> > > ready to take that on yet, I just don't understand it all enough
> yet.
> >
> > I think vm_normal_page() could use something like pfn_normal() which
> > isn't quite the same as pfn_valid()... or just use pfn_valid() but
> in
> > that case, that would mean removing a bunch of the BUG_ON's indeed.
> 
> That's exactly what my original patch does.  Would my patch break
> spufs?  Nick said my patch would break /dev/mem I think.

I missed your original patch. Can you resend it to me ? Nick, how would
it break /dev/mem ?

Cheers,
Ben.


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