On Thursday 11 February 2016 03:52 PM, Martin Schwidefsky wrote: > On Thu, 11 Feb 2016 14:58:26 +0530 > Vineet Gupta <Vineet.Gupta1 at synopsys.com> wrote: > >> Generic pgtable_trans_huge_deposit()/pgtable_trans_huge_withdraw() >> assume pgtable_t to be struct page * which is not true for all arches. >> Thus arc, s390, sparch end up with their own copies despite no special >> hardware requirements (unlike powerpc). > > s390 does have a special hardware requirement. pgtable_t is an address > for a 2K block of memory. It is *not* equivalent to a struct page * > which refers to a 4K block of memory. That has been the whole point > to introduce pgtable_t. Actually my reference to hardware requirement was more like powerpc style save a hash value some where etc. Now pgtable_t need not be struct page * even if the actual sizes are same - e.g. in ARC port I kept pgtable_t as pte_t * simply to avoid a few page_address() calls in mm code (you could argue that is was a micro-optimization, anyways..) So given I know nothing about s390 MMU internals, I still think you can switch to the update generic version despite 2K vs. 4K. Agree ? >> It seems massaging the code a bit can make it reusbale. > > Imho the new code for asm-generic looks fine, as long as the override > with __HAVE_ARCH_PGTABLE_DEPOSIT/__HAVE_ARCH_PGTABLE_WITHDRAW continues > to work I do not mind.
