Re: [rfc][patch 1/4] include: add callbacks to toggle reference counting for VM_MIXEDMAP pages

[Martin Schwidefsky <schwidefsky@de.ibm.com>]

On Wed, 2008-01-09 at 16:14 +0100, Carsten Otte wrote:
> include: add callbacks to toggle reference counting for VM_MIXEDMAP pages
> 
> This patch introduces two arch callbacks, which may optionally be implemented
> in case the architecutre does define __HAVE_ARCH_PTEP_NOREFCOUNT.
> 
> The first callback, pte_set_norefcount(__pte) is called by core-vm to indicate
> that subject page table entry is going to be inserted into a VM_MIXEDMAP vma.
> default implementation: 	noop
> s390 implementation:		set sw defined bit in pte
> proposed arm implementation:	noop
> 
> The second callback, mixedmap_refcount_pte(__pte) is called by core-vm to
> figure out whether or not subject pte requires reference counting in the
> corresponding struct page entry. A non-zero result indicates reference counting
> is required.
> default implementation:		(1)
> s390 implementation:		query sw defined bit in pte
> proposed arm implementation:	convert pte_t to pfn, use pfn_valid()
> 
> Signed-off-by: Carsten Otte <cotte@de.ibm.com>

For the s390 pieces of this patch:

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.


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