On 08/12/2023 03:25, Verma, Vishal L wrote: > On Thu, 2023-12-07 at 08:29 +0000, Zhijian Li (Fujitsu) wrote: >> Hi Vishal, >> >> >> On 07/12/2023 12:36, Vishal Verma wrote: >>> + >>> +What: /sys/bus/dax/devices/daxX.Y/memmap_on_memory >>> +Date: October, 2023 >>> +KernelVersion: v6.8 >>> +Contact: nvd...@lists.linux.dev >>> +Description: >>> + (RW) Control the memmap_on_memory setting if the dax device >>> + were to be hotplugged as system memory. This determines >>> whether >>> + the 'altmap' for the hotplugged memory will be placed on the >>> + device being hotplugged (memmap_on+memory=1) or if it will >>> be >> >> s/memmap_on+memory=1/memmap_on_memory=1 > > Thanks, will fix. >> >> >> I have a question here >> >> What relationship about memmap_on_memory and 'ndctl-create-namespace >> -M' option which >> specifies where is the vmemmap backed memory. >> I'm confused that memmap_on_memory=1 and '-M dev' are the same for >> nvdimm devdax mode ? >> > The main difference is that memory that comes from non-nvdimm sources, > such as hmem, or cxl, doesn't have a chance to set up the altmaps as > pmem can with '-M dev'. For these, memmap_on_memory does this as part > of the memory hotplug.
Thanks for your explanation. (I wrongly thought nvdimm.kmem was also controlled by '-M dev' before) feel free add: Tested-by: Li Zhijian <lizhij...@fujitsu.com>