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docs: update documentation for memory hot unplug

Browse source 
Add specification about how to use memory hot unplug, and add
a flow diagram to explain memory hot unplug process.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Zhu Guihua 2015-04-27 16:47:15 +08:00 • committed by Michael S. Tsirkin
parent 850d00700b
commit 4fccb4834d
2 changed files with 61 additions and 4 deletions
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42
docs/specs/acpi_mem_hotplug.txt
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@ -2,7 +2,7 @@ QEMU<->ACPI BIOS memory hotplug interface
--------------------------------------
ACPI BIOS GPE.3 handler is dedicated for notifying OS about memory hot-add
events.
and hot-remove events.
Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access):
---------------------------------------------------------------
@ -42,3 +42,43 @@ Selecting memory device slot beyond present range has no effect on platform:
ignored
- read accesses to memory hot-plug registers not documented above return
all bits set to 1.
Memory hot remove process diagram:
----------------------------------
+-------------+     +-----------------------+      +------------------+     
 |  1. QEMU    |     | 2. QEMU               |      |3. QEMU           |     
 |  device_del +---->+ device unplug request +----->+Send SCI to guest,|     
 |             |     |         cb            |      |return control to |     
 +-------------+     +-----------------------+      |management        |     
                                                    +------------------+     
                                                                             
 +---------------------------------------------------------------------+     
                                                                             
 +---------------------+              +-------------------------+            
 | OSPM:               | remove event | OSPM:                   |            
 | send Eject Request, |              | Scan memory devices     |            
 | clear remove event  +<-------------+ for event flags         |            
 |                     |              |                         |            
 +---------------------+              +-------------------------+            
           |                                                                 
           |                                                                 
 +---------v--------+            +-----------------------+                   
 | Guest OS:        |  success   | OSPM:                 |                   
 | process Ejection +----------->+ Execute _EJ0 method,  |                   
 | request          |            | set eject bit in flags|                   
 +------------------+            +-----------------------+                   
           |failure                         |                                
           v                                v                                
 +------------------------+      +-----------------------+                   
 | OSPM:                  |      | QEMU:                 |                   
 | set OST event & status |      | call device unplug cb |                   
 | fields                 |      |                       |                   
 +------------------------+      +-----------------------+                   
          |                                  |                               
          v                                  v                               
 +------------------+              +-------------------+                     
 |QEMU:             |              |QEMU:              |                     
 |Send OST QMP event|              |Send device deleted|                     
 |                  |              |QMP event          |                     
 +------------------+              |                   |                     
                                   +-------------------+