On Mon, Jun 19, 2017 at 11:13:46PM +0800, Ming Lei wrote: > On Mon, Jun 19, 2017 at 11:00 PM, Christoph Hellwig <hch@xxxxxx> wrote: > > On Mon, Jun 19, 2017 at 10:34:36PM +0800, Ming Lei wrote: > >> blk_queue_make_request() sets bounce for any highmem page for long time, > >> and in theory this patch might cause regression on 32bit arch, when > >> the controller can't handle higmem page really(especially in case of PAE), so > >> we may need to be careful about this change, especially on some old hardware. > > > > Which controller? > > I don't know. > > IMO, we can't just remove it because it is a bio based driver, the > bounce is not related with > a bio or req based driver, and it depends if the controller can handle > highmem page. pktcdvd is a stacking driver and forwards all data through either generic_make_request or blk_rq_map_kern + blk_execute_rq, both of which call blk_queue_bounce internally.
