Is VMWARE_BALLOON (Linux kernel option) intended for guests or hosts?

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http://unix.stackexchange.com – The kernel configuration option: VMware Balloon Driver (VMWARE_BALLOON) [N/m/y/?] (NEW) ? CONFIG_VMWARE_BALLOON: This is VMware physical memory management driver which acts like a "balloon" that can be inflated to reclaim physical pages by reserving them in the guest and invalidating them in the monitor, freeing up the underlying machine pages so they can be allocated to other guests. The balloon can also be deflated to allow the guest to use more physical memory. If unsure, say N. To compile this driver as a module, choose M here: the module will be called vmw_b (HowTos)