Messages in this thread | | | Date | Tue, 13 Sep 2011 16:48:47 +0800 | Subject | Re: [PATCH] EFI: Do not use __pa() to get the physical address of an ioremapped memory range | From | huang ying <> |
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On Mon, Sep 12, 2011 at 10:52 PM, Matt Fleming <matt@console-pimps.org> wrote: > On Fri, 2011-09-02 at 13:12 +0800, huang ying wrote: >> On Thu, Sep 1, 2011 at 8:28 PM, Matt Fleming <matt@console-pimps.org> wrote: >> > >> > Hmm.. does anyone know why we ioremap_cache() the memory on >> > CONFIG_X86_32 instead of ioremap_nocache()? In the case of >> > EFI_MEMORY_MAPPED_IO the memory really needs to be uncached. Then if >> > we've ioremap'd the memory we should skip set_memory_uc() altogether, >> > no? >> >> Because whether the mapping should be cached is determined by md->attr >> instead of md->type. And besides UC, we may add WC, etc support. > > Confused. > > The CONFIG_X86_64 version of efi_ioremap() looks like this, > > void __iomem *__init efi_ioremap(unsigned long phys_addr, unsigned long size, > u32 type) > { > unsigned long last_map_pfn; > > if (type == EFI_MEMORY_MAPPED_IO) > return ioremap(phys_addr, size); > > Which uses md->type to figure out if we should call ioremap(), which on > x86 is #define'd to ioremap_nocache(). CONFIG_X86_32 doesn't do this, > but it looks to me like it should.
I don't think this type based solution is the perfect one.
Best Regards, Huang Ying -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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