On Tue 23-04-19 16:38:43, Pavel Tatashin wrote:
sparsemem section size determines the maximum size and alignment
that
is allowed to offline/online memory block. The bigger the size the less
the clutter in /sys/devices/system/memory/*. On the other hand, however,
there is less flexability in what granules of memory can be added and
removed.
Recently, it was enabled in Linux to hotadd persistent memory that
can be either real NV device, or reserved from regular System RAM
and has identity of devdax.
The problem is that because ARM64's section size is 1G, and devdax must
have 2M label section, the first 1G is always missed when device is
attached, because it is not 1G aligned.
Allow, better flexibility by making section size configurable.
Is there any inherent reason (64k page size?) that enforces such a large
memsection?
--
Michal Hocko
SUSE Labs