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SubjectRe: [PATCH v4 5/7] x86, mm, pat: Refactor !pat_enabled handling
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On Mon, 2014-11-03 at 20:01 +0100, Thomas Gleixner wrote:
> On Mon, 27 Oct 2014, Toshi Kani wrote:
> > diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
> > index ee58a0b..96aa8bf 100644
> > --- a/arch/x86/mm/iomap_32.c
> > +++ b/arch/x86/mm/iomap_32.c
> > @@ -70,29 +70,23 @@ void *kmap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
> > return (void *)vaddr;
> > }
> >
> > -/*
> > - * Map 'pfn' using protections 'prot'
> > - */
> > -#define __PAGE_KERNEL_WC (__PAGE_KERNEL | \
> > - cachemode2protval(_PAGE_CACHE_MODE_WC))
> > -
> > void __iomem *
> > iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot)
> > {
> > /*
> > - * For non-PAT systems, promote PAGE_KERNEL_WC to PAGE_KERNEL_UC_MINUS.
> > - * PAGE_KERNEL_WC maps to PWT, which translates to uncached if the
> > - * MTRR is UC or WC. UC_MINUS gets the real intention, of the
> > - * user, which is "WC if the MTRR is WC, UC if you can't do that."
> > + * For non-PAT systems, translate non-WB request to UC- just in
> > + * case the caller set the PWT bit to prot directly without using
> > + * pgprot_writecombine(). UC- translates to uncached if the MTRR
> > + * is UC or WC. UC- gets the real intention, of the user, which is
> > + * "WC if the MTRR is WC, UC if you can't do that."
> > */
> > - if (!pat_enabled && pgprot_val(prot) == __PAGE_KERNEL_WC)
> > + if (!pat_enabled && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
> > prot = __pgprot(__PAGE_KERNEL |
> > cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
> >
> > return (void __force __iomem *) kmap_atomic_prot_pfn(pfn, prot);
> > }
> > EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn);
> > -#undef __PAGE_KERNEL_WC
>
> Rejects. Please update against Juergens latest.

Yes, I have addressed this merge conflict in my next version. I will
submit it shortly after all other comments are addressed. :-)

Thanks,
-Toshi



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