Re: [Xen-devel] Re: [PATCH 1 of 7] x86: add _PAGE_IOMAP pte flag for IO mappings

[Avi Kivity <avi@xxxxxxxxxxxx>]

Avi Kivity wrote:
> > I'm not sure; I still don't really understand how _PAGE_SPECIAL gets
> > used, other than being user-mode mapping only.  But in principle,
> > _PAGE_IOMAP could be set on both kernel and user mappings (if you direct
> > map a device into a process address space), so I think they would
> > conflict then?
> >
> >   
> It's a "don't refcount me" flag, which is not sematically the same as 
> I/O, but may be close enough.
Actually it's more of a "no struct page" flag, which implies no 
refcounting.  And not having a struct page should correspond well to a 
pte not requiring pfn->mfn conversion and being an I/O page.
--
error compiling committee.c: too many arguments to function


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