Add description about event notification callback routine to the document.
Signed-off-by: Yasunori Goto <[email protected]>
---
Documentation/memory-hotplug.txt | 58 ++++++++++++++++++++++++++++++++++++---
1 file changed, 55 insertions(+), 3 deletions(-)
Index: current/Documentation/memory-hotplug.txt
===================================================================
--- current.orig/Documentation/memory-hotplug.txt 2007-10-17 15:57:50.000000000 +0900
+++ current/Documentation/memory-hotplug.txt 2007-10-17 21:26:30.000000000 +0900
@@ -2,7 +2,8 @@
Memory Hotplug
==============
-Last Updated: Jul 28 2007
+Created: Jul 28 2007
+Add description of notifier of memory hotplug Oct 11 2007
This document is about memory hotplug including how-to-use and current status.
Because Memory Hotplug is still under development, contents of this text will
@@ -24,7 +25,8 @@ be changed often.
6.1 Memory offline and ZONE_MOVABLE
6.2. How to offline memory
7. Physical memory remove
-8. Future Work List
+8. Memory hotplug event notifier
+9. Future Work List
Note(1): x86_64's has special implementation for memory hotplug.
This text does not describe it.
@@ -307,8 +309,58 @@ Need more implementation yet....
- Notification completion of remove works by OS to firmware.
- Guard from remove if not yet.
+--------------------------------
+8. Memory hotplug event notifier
+--------------------------------
+Memory hotplug has event notifer. There are 6 types of notification.
+
+MEMORY_GOING_ONLINE
+ Generated before new memory becomes available in order to be able to
+ prepare subsystems to handle memory. The page allocator is still unable
+ to allocate from the new memory.
+
+MEMORY_CANCEL_ONLINE
+ Generated if MEMORY_GOING_ONLINE fails.
+
+MEMORY_ONLINE
+ Generated when memory has succesfully brought online. The callback may
+ allocate pages from the new memory.
+
+MEMORY_GOING_OFFLINE
+ Generated to begin the process of offlining memory. Allocations are no
+ longer possible from the memory but some of the memory to be offlined
+ is still in use. The callback can be used to free memory known to a
+ subsystem from the indicated memory section.
+
+MEMORY_CANCEL_OFFLINE
+ Generated if MEMORY_GOING_OFFLINE fails. Memory is available again from
+ the section that we attempted to offline.
+
+MEMORY_OFFLINE
+ Generated after offlining memory is complete.
+
+A callback routine can be registered by
+ hotplug_memory_notifier(callback_func, priority)
+
+The second argument of callback function (action) is event types of above.
+The third argument is passed by pointer of struct memory_notify.
+
+struct memory_notify {
+ unsigned long start_pfn;
+ unsigned long nr_pages;
+ int status_cahnge_nid;
+}
+
+start_pfn is start_pfn of online/offline memory.
+nr_pages is # of pages of online/offline memory.
+status_change_nid is set node id when N_HIGH_MEMORY of nodemask is (will be)
+set/clear. It means a new(memoryless) node gets new memory by online and a
+node loses all memory. If this is -1, then nodemask status is not changed.
+If status_changed_nid >= 0, callback should create/discard structures for the
+node if necessary.
+
--------------
-8. Future Work
+9. Future Work
--------------
- allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
sysctl or new control file.
--
Yasunori Goto
-
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