Messages in this thread | | | Date | Wed, 4 Feb 2015 17:52:56 +0000 | From | Catalin Marinas <> | Subject | Re: [PATCH v8 02/21] acpi: fix acpi_os_ioremap for arm64 |
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On Wed, Feb 04, 2015 at 04:16:34PM +0000, Timur Tabi wrote: > On 02/04/2015 10:08 AM, Mark Salter wrote: > > acpi_os_remap() is used to map ACPI tables. These tables may be in ram > > which are already included in the kernel's linear RAM mapping. So we > > need ioremap_cache to avoid two mappings to the same physical page > > having different caching attributes. > > Would it be possible to modify ioremap() so that it can tell whether the > memory is already mapped in some way, and then use a compatible remapping?
No. We have some semantics for ioremap() and it should return non-cacheable mapping.
ioremap_cache() checks whether the page is RAM already and returns the existing kernel linear mapping on arm64.
-- Catalin
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