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.
