On 1/18/23 3:54 PM, Bart Van Assche wrote: > Prepare for introducing support for segments smaller than the page size > by introducing the request queue flag QUEUE_FLAG_SUB_PAGE_SEGMENTS. > Introduce CONFIG_BLK_SUB_PAGE_SEGMENTS to prevent that performance of > block drivers that support segments >= PAGE_SIZE would be affected. > > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Ming Lei <ming.lei@xxxxxxxxxx> > Cc: Keith Busch <kbusch@xxxxxxxxxx> > Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx> > --- > block/Kconfig | 9 +++++++++ > include/linux/blkdev.h | 7 +++++++ > 2 files changed, 16 insertions(+) > > diff --git a/block/Kconfig b/block/Kconfig > index 5d9d9c84d516..e85061d2175b 100644 > --- a/block/Kconfig > +++ b/block/Kconfig > @@ -35,6 +35,15 @@ config BLOCK_LEGACY_AUTOLOAD > created on demand, but scripts that manually create device nodes and > then call losetup might rely on this behavior. > > +config BLK_SUB_PAGE_SEGMENTS > + bool "Support segments smaller than the page size" > + default n > + help > + Most storage controllers support DMA segments larger than the typical > + size of a virtual memory page. Some embedded controllers only support > + DMA segments smaller than the page size. Enable this option to support > + such controllers. This should not be a visible option at all, affected drivers should just select it. -- Jens Axboe
