Re: [PATCH] arm64: configurable sparsemem section size

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.