xen: enable BALLOON_MEMORY_HOTPLUG by default

Without it a PVH dom0 is mostly useless, as it would balloon down huge
amounts of RAM in order get physical address space to map foreign
memory and grants, ultimately leading to an out of memory situation.

Such option is also needed for HVM or PVH driver domains, since they
also require mapping grants into physical memory regions.

Suggested-by: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: xen-devel@lists.xenproject.org

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 57ddd6f4b729b00a6e205aef3b8018d4cff316b6..c344bcffd89d1491a24ee18cff73f9eb57d88735 100644 (file)
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -13,6 +13,7 @@ config XEN_BALLOON
 config XEN_BALLOON_MEMORY_HOTPLUG
        bool "Memory hotplug support for Xen balloon driver"
        depends on XEN_BALLOON && MEMORY_HOTPLUG
+       default y
        help
          Memory hotplug support for Xen balloon driver allows expanding memory
          available for the system above limit declared at system startup.