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    SubjectRE: [patch 09/11] PAT x86: Add ioremap_wc support
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    >-----Original Message-----
    >From: Andi Kleen [mailto:andi@firstfloor.org]
    >Sent: Thursday, January 10, 2008 11:09 AM
    >To: Pallipadi, Venkatesh
    >Cc: ebiederm@xmission.com; rdreier@cisco.com;
    >torvalds@linux-foundation.org; gregkh@suse.de;
    >airlied@skynet.ie; davej@redhat.com; mingo@elte.hu;
    >tglx@linutronix.de; hpa@zytor.co;
    >linux-kernel@vger.kernel.org; Siddha, Suresh B
    >Subject: Re: [patch 09/11] PAT x86: Add ioremap_wc support
    >
    >venkatesh.pallipadi@intel.com writes:
    >> Index: linux-2.6.git/include/asm-generic/iomap.h
    >> ===================================================================
    >> --- linux-2.6.git.orig/include/asm-generic/iomap.h
    >2008-01-08 03:31:37.000000000 -0800
    >> +++ linux-2.6.git/include/asm-generic/iomap.h
    >2008-01-08 05:15:56.000000000 -0800
    >> @@ -65,4 +65,8 @@
    >> extern void __iomem *pci_iomap(struct pci_dev *dev, int
    >bar, unsigned long max);
    >> extern void pci_iounmap(struct pci_dev *dev, void __iomem *);
    >>
    >> +#ifndef ioremap_wc
    >> +#define ioremap_wc ioremap_nocache
    >> +#endif
    >
    >I don't think that's a good idea. Drivers should be able to
    >detect this somehow.
    >Handling UC mappings as WC will probably give very poor results.
    >

    It is the other way. ioremap_wc aliases to ioremap_nocache.
    This was based on earlier feedback from Roland.
    >From: Roland Dreier [mailto:rdreier@cisco.com]
    >I think ioremap_wc() needs to be available on all archs for this to be
    >really useful to drivers. It can be a fallback to ioremap_nocache()
    >everywhere except 64-bit x86, but it's not nice for every driver that
    >wants to use this to need an "#ifdef X86" or whatever.

    Thanks,
    Venki


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