On Wed, Feb 04, 2015 at 06:58:14PM +0000, Mark Salter wrote: > On Wed, 2015-02-04 at 17:57 +0000, Catalin Marinas wrote: > > On Wed, Feb 04, 2015 at 04:08:27PM +0000, 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. > > > > What's the call path to acpi_os_ioremap() on such tables already in the > > linear mapping? I can see an acpi_map() function which already takes > > care of the RAM mapping case but there are other cases where > > acpi_os_ioremap() is called directly. For example, > > acpi_os_read_memory(), can it be called on both RAM and I/O? > > acpi_map() is the one I've seen. By default, if should_use_kmap() is not patched for arm64, it translates to page_is_ram(); acpi_map() would simply use a kmap() which returns the current kernel linear mapping on arm64. > I'm not sure about others. Question for the ARM ACPI guys: what happens if you implement acpi_os_ioremap() on arm64 as just ioremap()? Do you get any WARN_ON() (__ioremap_caller() checks whether the memory is RAM)? -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
