Logfile: Changes for version 20180927

Version 20180927

1 files changed, 93 insertions, 0 deletions

diff --git a/documents/changes.txt b/documents/changes.txt
index d2a76e90a..c416898bb 100644
--- a/documents/changes.txt
+++ b/documents/changes.txt
@@ -1,4 +1,97 @@
 ----------------------------------------
+27 September 2018. Summary of changes for version 20180927:
+
+
+1) ACPICA kernel-resident subsystem:
+
+Updated the GPE support to clear the status of all ACPI events when 
+entering any/all sleep states in order to avoid premature wakeups. In 
+theory, this may cause some wakeup events to be missed, but the 
+likelihood of this is small. This change restores the original behavior 
+of the ACPICA code in order to fix a regression seen from the previous 
+"Stop unconditionally clearing ACPI IRQs during suspend/resume" change. 
+This regression could cause some systems to incorrectly wake immediately.
+
+Updated the execution of the _REG methods during initialization and 
+namespace loading to bring the behavior into closer conformance to the 
+ACPI specification and other ACPI implementations:
+
+From the ACPI specification 6.2A, section 6.5.4 "_REG (Region):
+    "Control methods must assume all operation regions are inaccessible 
+until the _REG(RegionSpace, 1) method is executed"
+
+    "The exceptions to this rule are:
+1.  OSPM must guarantee that the following operation regions are always 
+accessible:
+    SystemIO operation regions.
+    SystemMemory operation regions when accessing memory returned by the 
+System Address Map reporting interfaces."
+
+Since the state of both the SystemIO and SystemMemory address spaces are 
+defined by the specification to never change, this ACPICA change ensures 
+that now _REG is never called on them. This solves some problems seen in 
+the field and provides compatibility with other ACPI implementations. An 
+update to the upcoming new version of the ACPI specification will help 
+clarify this behavior.
+
+Updated the implementation of support for the Generic Serial Bus. For the 
+"bidirectional" protocols, the internal implementation now automatically 
+creates a return data buffer of the maximum size (255). This handles the 
+worst-case for data that is returned from the serial bus handler, and 
+fixes some problems seen in the field. This new buffer is directly 
+returned to the ASL. As such, there is no true "bidirectional" buffer, 
+which matches the ACPI specification. This is the reason for the "double 
+store" seen in the example ASL code in the specification, shown below:
+
+Word Process Call (AttribProcessCall):
+    OperationRegion(TOP1, GenericSerialBus, 0x00, 0x100)
+    Field(TOP1, BufferAcc, NoLock, Preserve)
+    {
+        FLD1, 8, // Virtual register at command value 1.
+    }
+
+    Name(BUFF, Buffer(20){}) // Create GenericSerialBus data buffer
+                             // as BUFF
+    CreateWordField(BUFF, 0x02, DATA) // DATA = Data (Word)
+
+    Store(0x5416, DATA)               // Save 0x5416 into the data buffer
+    Store(Store(BUFF, FLD1), BUFF)    // Invoke a write/read Process Call 
+transaction
+                           // This is the "double store". The write to
+                           // FLD1 returns a new buffer, which is stored
+                           // back into BUFF with the second Store.
+
+
+2) iASL Compiler/Disassembler and Tools:
+
+iASL: Implemented detection of extraneous/redundant uses of the Offset() 
+operator within a Field Unit list. A remark is now issued for these. For 
+example, the first two of the Offset() operators below are extraneous. 
+Because both the compiler and the interpreter track the offsets 
+automatically, these Offsets simply refer to the current offset and are 
+unnecessary. Note, when optimization is enabled, the iASL compiler will 
+in fact remove the redundant Offset operators and will not emit any AML 
+code for them.
+
+    OperationRegion (OPR1, SystemMemory, 0x100, 0x100)
+    Field (OPR1)
+    {
+        Offset (0),     // Never needed
+        FLD1, 32,
+        Offset (4),     // Redundant, offset is already 4 (bytes)
+        FLD2, 8,
+        Offset (64),    // OK use of Offset.
+        FLD3, 16,
+    }
+dsdt.asl     14:         Offset (0),
+Remark   2158 -                 ^ Unnecessary/redundant use of Offset 
+operator
+
+dsdt.asl     16:         Offset (4),
+Remark   2158 -                 ^ Unnecessary/redundant use of Offset 
+operator
+
+----------------------------------------
 10 August 2018. Summary of changes for version 20180810: