Hello Ingo, On 10/01/2013 01:46 PM, Ingo Molnar wrote: > > * Zhang Yanfei <zhangyanfei.yes@xxxxxxxxx> wrote: > >> @@ -153,11 +153,18 @@ config MOVABLE_NODE >> help >> Allow a node to have only movable memory. Pages used by the kernel, >> such as direct mapping pages cannot be migrated. So the corresponding >> + memory device cannot be hotplugged. This option allows the following >> + two things: >> + - When the system is booting, node full of hotpluggable memory can >> + be arranged to have only movable memory so that the whole node can >> + be hotplugged. (need movable_node boot option specified). > > So this is _exactly_ what I complained about earlier: why is the > movable_node boot option needed to get that extra functionality? It's > clearly not just a drop-in substitute to CONFIG_MOVABLE_NODE but extends > its functionality, right? Generally speaking, CONFIG_MOVABLE_NODE is used to allow a node to have only movable memory. Firstly, we didn't support the functionality to support boot-time configuration. That said, before this patchset, we only support later hot-add node to have only movable memory but any node that is dectected at boot-time cannot. So here is movable_node option, to protect the kernel from using hotpluggable memory at boot-time and if a node is full of hotpluggable memory, this node is arranged to have only movable memory and can be hot-removed after the system is up. > > Boot options are _very_ poor user interface. If you don't want to enable > it by default then turn this sub-functionality into > CONFIG_MOVABLE_NODE_AUTO and keep it default-off - but don't pretend that > this is only about CONFIG_MOVABLE_NODE alone - it isnt: as described above > the 'movable_node' is needed for the full functionality to be available! As explained above, we need the boot option to only disable boot-time memory-hotplug configuration not the whole MOVABLE_NODE functionality. Thanks -- Thanks. Zhang Yanfei -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>