On Fri, Oct 20, 2017 at 08:23:02AM -0700, Dan Williams wrote: > Yes, however it seems these drivers / platforms have been living with > the lack of struct page for a long time. So they either don't use DAX, > or they have a constrained use case that never triggers > get_user_pages(). If it is the latter then they could introduce a new > configuration option that bypasses the pfn_t_devmap() check in > bdev_dax_supported() and fix up the get_user_pages() paths to fail. > So, I'd like to understand how these drivers have been using DAX > support without struct page to see if we need a workaround or we can > go ahead delete this support. If the usage is limited to > execute-in-place perhaps we can do a constrained ->direct_access() for > just that case. For axonram I doubt anyone is using it any more - it was a very for the IBM Cell blades, which were produceѕ in a rather limited number. And Cell basically seems to be dead as far as I can tell. For S/390 Martin might be able to help out what the status of xpram in general and DAX support in particular is.
