Paul Mackerras <paulus@xxxxxxxxxx> writes: > On Mon, Feb 08, 2016 at 02:50:19PM +0530, Aneesh Kumar K.V wrote: >> With next generation power processor, we are having a new mmu model >> [1] that require us to maintain a different linux page table format. >> >> Inorder to support both current and future ppc64 systems with a single >> kernel we need to make sure kernel can select between different page >> table format at runtime. With the new MMU (radix MMU) added, we will >> have to dynamically switch between different protection map. Hence >> override vm_get_page_prot instead of using arch_vm_get_page_prot. We >> also drop arch_vm_get_page_prot since only powerpc used it. > > What's different about ISA v3.0 that means that the protection_map[] > entries need to be different? > > If it's just different bit assignments for things like _PAGE_READ > etc., couldn't we fix this up at early boot time by writing new values > into protection_map[]? Is there a reason why that wouldn't work, or > why you don't want to do that? > Yes, that is other way to do this. But I thought it is easier to have different protection_map array for radix and hash. That made the code more readable. -aneesh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>