On Thu, 26 Aug 2010 02:58:57 +0200, KAMEZAWA Hiroyuki [off-list ref] wrote:

Hmm, you may not like this..but how about following kind of interface ?

Now, memoyr hotplug supports following operation to free and _isolate_
memory region.
	# echo offline > /sys/devices/system/memory/memoryX/state

Then, a region of memory will be isolated. (This succeeds if there are free
memory.)

Add a new interface.

	% echo offline > /sys/devices/system/memory/memoryX/state
	# extract memory from System RAM and make them invisible from buddy allocator.

	% echo cma > /sys/devices/system/memory/memoryX/state
	# move invisible memory to cma.

At this point I need to say that I have no experience with hotplug memory but
I think that for this to make sense the regions of memory would have to be
smaller.  Unless I'm misunderstanding something, the above would convert
a region of sizes in order of GiBs to use for CMA.

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