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Re: [Qemu-devel] [RFC PATCH 2/9][SeaBIOS] Implement acpi-dsdt functions


From: Igor Mammedov
Subject: Re: [Qemu-devel] [RFC PATCH 2/9][SeaBIOS] Implement acpi-dsdt functions for memory hotplug.
Date: Fri, 20 Apr 2012 12:55:24 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1

On 04/19/2012 04:08 PM, Vasilis Liaskovitis wrote:
Extend the DSDT to include methods for handling memory hot-add and hot-remove
notifications and memory device status requests. These functions are called
from the memory device SSDT methods.

Eject has only been tested with level gpe event, but will be changed to edge gpe
event soon, according to recent master patch for other ACPI hotplug events.

Signed-off-by: Vasilis Liaskovitis<address@hidden>
---
  src/acpi-dsdt.dsl |   68 +++++++++++++++++++++++++++++++++++++++++++++++++++-
  1 files changed, 66 insertions(+), 2 deletions(-)

diff --git a/src/acpi-dsdt.dsl b/src/acpi-dsdt.dsl
index 4bdc268..184daf0 100644
--- a/src/acpi-dsdt.dsl
+++ b/src/acpi-dsdt.dsl
@@ -709,9 +709,72 @@ DefinitionBlock (
              }
              Return(One)
          }
-    }

+        /* Objects filled in by run-time generated SSDT */
+        External(MTFY, MethodObj)
+        External(MEON, PkgObj)
+
+        Method (CMST, 1, NotSerialized) {
+            // _STA method - return ON status of memdevice
+            // Local0 = MEON flag for this cpu
+            Store(DerefOf(Index(MEON, Arg0)), Local0)
+            If (Local0) { Return(0xF) } Else { Return(0x0) }
+        }
+        /* Memory eject notify method */
+        OperationRegion(MEMJ, SystemIO, 0xaf40, 32)
+        Field (MEMJ, ByteAcc, NoLock, Preserve)
+        {
+            MPE, 256
+        }
+
+        Method (MPEJ, 2, NotSerialized) {
+            // _EJ0 method - eject callback
+            Store(ShiftLeft(1,Arg0), MPE)
+            Sleep(200)
+        }
MPE is write only and only one memslot is ejected at a time. Why 256 bit-field 
is here then?
Could we use just 1 byte and write a slot number into it and save some io 
address space this way?

+
+        /* Memory hotplug notify method */
+        OperationRegion(MEST, SystemIO, 0xaf20, 32)
It's more a suggestion: move it a bit farther to allow maybe 1024 cpus in the 
future.
That will prevent compatibility a headache, if we decide to expand support to 
more then
256 cpus.

Or event better to make this address configurable in run-time and build this 
var along
with SSDT (converting along the way all other hard-coded io ports to the same 
generic
run-time interface). This wish is out of scope of this patch-set, but what
do you think about the idea?

+        Field (MEST, ByteAcc, NoLock, Preserve)
+        {
+            MES, 256
+        }
+
+        Method(MESC, 0) {
+            // Local5 = active memdevice bitmap
+            Store (MES, Local5)
+            // Local2 = last read byte from bitmap
+            Store (Zero, Local2)
+            // Local0 = memory device iterator
+            Store (Zero, Local0)
+            While (LLess(Local0, SizeOf(MEON))) {
+                // Local1 = MEON flag for this memory device
+                Store(DerefOf(Index(MEON, Local0)), Local1)
+                If (And(Local0, 0x07)) {
+                    // Shift down previously read bitmap byte
+                    ShiftRight(Local2, 1, Local2)
+                } Else {
+                    // Read next byte from memdevice bitmap
+                    Store(DerefOf(Index(Local5, ShiftRight(Local0, 3))), 
Local2)
+                }
+                // Local3 = active state for this memory device
+                Store(And(Local2, 1), Local3)

+                If (LNotEqual(Local1, Local3)) {
+                    // State change - update MEON with new state
+                    Store(Local3, Index(MEON, Local0))
+                    // Do MEM notify
+                    If (LEqual(Local3, 1)) {
+                        MTFY(Local0, 1)
+                    } Else {
+                        MTFY(Local0, 3)
+                    }
+                }
+                Increment(Local0)
+            }
+            Return(One)
+        }
+    }
  /****************************************************************
   * General purpose events
   ****************************************************************/
@@ -732,7 +795,8 @@ DefinitionBlock (
              Return(\_SB.PRSC())
          }
          Method(_L03) {
-            Return(0x01)
+            // Memory hotplug event
+            Return(\_SB.MESC())
          }
          Method(_L04) {
              Return(0x01)

--
-----
 Igor



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