>From [PATCH 6/8] dax: sub-division support: Device-DAX is a mechanism to establish mappings of performance / feature differentiated memory with strict fault behavior guarantees. With sub-division support a platform owner can provision sub-allocations of a dax-region into separate devices. The provisioning mechanism follows the same scheme as the libnvdimm sub-system in that a 'seed' device is created at initialization time that can be resized from zero to become enabled.
Unlike the nvdimm sub-system there is no on media labelling scheme associated with this partitioning. Provisioning decisions are ephemeral / not automatically restored after reboot. While the initial use case of device-dax is persistent memory other uses case may be volatile, so the device-dax core is unable to assume the underlying memory is pmem. The task of recalling a partitioning scheme or permissions on the device(s) is left to userspace. For persistent allocations, naming, and permissions automatically recalled by the kernel, use filesystem-DAX. For a userspace helper library and utility for manipulating device-dax instances see libdaxctl and the daxctl utility here: https://github.com/pmem/ndctl --- Dan Williams (8): dax: add region-available-size attribute dax: add region 'id', 'size', and 'align' attributes dax: register seed device dax: use multi-order radix for resource lookup dax: refactor locking out of size calculation routines dax: sub-division support dax: add / remove dax devices after provisioning dax: add debug for region available_size drivers/dax/Kconfig | 1 drivers/dax/dax.c | 747 ++++++++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 698 insertions(+), 50 deletions(-)
