On Wed, Aug 02 2017 at 1:58pm -0400, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > Rather than have device-mapper directly 'select DAX', let the fact that > BLK_DEV_PMEM selects dax act as a gate for the device-mapper dax > support. We arrange for all the dax core routines to compile to nops > when CONFIG_DAX=n. With that in place we can simply handle the > alloc_dax() error as expected and ifdef out the other device-mapper-dax > support code. > > Now, if dax is provided by a leaf driver that driver may only arrange to > compile the dax core as a module. Since device-mapper dax support is > consumed by the always-built-in portion of the device-mapper > implementation we need to upgrade from DAX=m to DAX=y. I applied the patches and then got nervous once I dug in.. this last paragraph makes little sense to me. "the always-built-in portion of the device-mapper implementation" is why: DM core can happily be compiled as a module (dm-mod.ko). And I'm not sure why you're referencing DAX related drivers/md/dm-builtin.c, why are you attachd DM's DAX support to that? I'm not seeing where that is actually happening. I don't see why DM's support for DAX would need to force DAX to be builtin rather than just a module. Sorry I didn't get around to looking at this until now, but it seems you went wrong along the way? Or maybe I'm just missing something? Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
