Re: [PATCH v5 0/5] Add movablecore_map boot option

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On 01/16/2013 09:08 PM, Yasuaki Ishimatsu wrote:

I thought about the method of specifying the node. But I think
this method is inconvenience. Node number is decided by OS.
So the number is changed easily.

for example:

o exmaple 1
   System has 3 nodes:
   node0, node1, node2

   When user remove node1, the system has:
   node0, node2

   But after rebooting the system, the system has:
   node0, node1

   So node2 becomes node1.

o example 2:
   System has 2 nodes:
   0x40000000 - 0x7fffffff : node0
   0xc0000000 - 0xffffffff : node1

   When user add a node wchih memory range is [0x80000000 - 0xbfffffff],
   system has:
   0x40000000 - 0x7fffffff : node0
   0xc0000000 - 0xffffffff : node1
   0x80000000 - 0xbfffffff : node2

   But after rebooting the system, the system's node may become:
   0x40000000 - 0x7fffffff : node0
   0x80000000 - 0xbfffffff : node1
   0xc0000000 - 0xffffffff : node2

   So node nunber is changed.

Specifying node number may be easy method than specifying memory
range. But if user uses node number for specifying removable memory,
user always need to care whether node number is changed or not at
every hotplug operation.



Well, there are only two options:

1. The user doesn't care which nodes are movable. In that case, the user may just want to specify a target as a percentage of memory to make movable -- effectively a "slider" on the performance vs. reliability spectrum. The kernel can then assign nodes arbitrarily.

2. If the user *does* care which nodes are movable, then the user needs to be able to specify that *in a way that makes sense to the user*. This may mean involving the DMI information as well as SRAT in order to get "silk screen" type information out.

	-hpa



--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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