[PATCH 2/2] memory_hotplug: introduce memhp_default_state= command line parameter

Vitaly Kuznetsov
2016-04-06T13:45:26Z

CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE specifies the default value for the
memory hotplug onlining policy. Add a command line parameter to make it
possible to override the default. It may come handy for debug and testing
purposes.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
Documentation/kernel-parameters.txt | 8 ++++++++
mm/memory_hotplug.c | 11 +++++++++++
2 files changed, 19 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ecc74fa..b05ee2f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2141,6 +2141,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
[KNL,SH] Allow user to override the default size for
per-device physically contiguous DMA buffers.

+ memhp_default_state=online/offline
+ [KNL] Set the initial state for the memory hotplug
+ onlining policy. If not specified, the default value is
+ set according to the
+ CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
+ option.
+ See Documentation/memory-hotplug.txt.
+
memmap=exactmap [KNL,X86] Enable setting of an exact
E820 memory map, as specified by the user.
Such memmap=exactmap lines can be constructed based on
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 072e0a1..179f3af 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -85,6 +85,17 @@ bool memhp_auto_online = true;
#endif
EXPORT_SYMBOL_GPL(memhp_auto_online);

+static int __init setup_memhp_default_state(char *str)
+{
+ if (!strcmp(str, "online"))
+ memhp_auto_online = true;
+ else if (!strcmp(str, "offline"))
+ memhp_auto_online = false;
+
+ return 1;
+}
+__setup("memhp_default_state=", setup_memhp_default_state);
+
void get_online_mems(void)
{
might_sleep();
--
2.5.5