- Requirement
Reduce PCD database size for multi-SKU case to save image size at build time
and memory resource at boot time.
- Current limitation
When multiple SKUs are enabled, the full set of PCD values for all SKUs will be
generated into PCD database,
and HOB will be created for the PCD database, the HOB will consume much memory
resource when many SKUs are specified,
but the HOB length and pre-memory phase memory resource are limited.
- Proposal
BaseTools can generate the optimized PCD database to save the image size at
build time,
the optimized PCD database layout will be like below, the PCD database will be
composed of the full
default SKU data(PCD_DATABASE_INIT) and the non-default SKU delta
data(PCD_DATABASE_SKU_DELTA).
PCD driver will build HOB to store the full default SKU data, and patch HOB
data based on
non-default SKU delta data for the SKU set by SetSku(), it can save memory
resource at boot time.
//
// PCD database layout:
// +---------------------------------+
// | PCD_DATABASE_INIT (DEFAULT SKU) |
// +---------------------------------+
// | PCD_DATABASE_SKU_DELTA (SKU A) |
// +---------------------------------+
// | PCD_DATABASE_SKU_DELTA (SKU B) |
// +---------------------------------+
// | ...... |
// +---------------------------------+
//
The patch below shows the detailed PCD database format change.
BaseTools, PCD database and driver updates are needed for this proposal.
BaseTools can even be intelligent to generate smallest SKU delta based on the
PCD values for different SKUs and the relationship between SKUs.
For single SKU (default) case, this proposal is expected to have no impact.
Note: For multi-SKU case, PCD database format will be changed, so PCD driver
will have to be updated together with BaseTools.
Cc: Michael Kinney <michael.d.kin...@intel.com>
Cc: Liming Gao <liming....@intel.com>
Cc: Tim Lewis <tim.le...@insyde.com>
Cc: Yonghong Zhu <yonghong....@intel.com>
---
.../Include/Guid/PcdDataBaseSignatureGuid.h | 32 +++++++++++++++++-----
1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/MdeModulePkg/Include/Guid/PcdDataBaseSignatureGuid.h
b/MdeModulePkg/Include/Guid/PcdDataBaseSignatureGuid.h
index d2e848800b75..0069823458cd 100644
--- a/MdeModulePkg/Include/Guid/PcdDataBaseSignatureGuid.h
+++ b/MdeModulePkg/Include/Guid/PcdDataBaseSignatureGuid.h
@@ -62,11 +62,6 @@ typedef struct {
} DYNAMICEX_MAPPING;
typedef struct {
- UINT32 SkuDataStartOffset; // Offset(with DATUM TYPE info) from the
PCD_DB.
- UINT32 SkuIdTableOffset; // Offset from the PCD_DB.
-} SKU_HEAD;
-
-typedef struct {
UINT32 StringIndex; // Offset in String Table in units of UINT8.
UINT32 DefaultValueOffset; // Offset of the Default Value.
UINT16 GuidTableIndex; // Offset in Guid Table in units of GUID.
@@ -115,7 +110,6 @@ typedef struct {
// Padding is needed to keep necessary alignment
//
//SKU_ID SkuIdTable[]; // SkuIds system
supports.
- //SKU_ID SkuIndexTable[]; // SkuIds for
each PCD with SKU enable.
//UINT64 ValueUint64[];
//UINT32 ValueUint32[];
//VPD_HEAD VpdHead[]; // VPD Offset
@@ -125,7 +119,6 @@ typedef struct {
//STRING_HEAD StringHead[]; // String PCD
//PCD_NAME_INDEX PcdNameTable[]; // PCD name
index info. It can be accessed by the PcdNameTableOffset.
//VARIABLE_HEAD VariableHead[]; // HII PCD
- //SKU_HEAD SkuHead[]; // Store SKU
info for each PCD with SKU enable.
//UINT8 StringTable[]; // String for
String PCD value and HII PCD Variable Name. It can be accessed by
StringTableOffset.
//SIZE_INFO SizeTable[]; // MaxSize and
CurSize for String PCD. It can be accessed by SizeTableOffset.
//UINT16 ValueUint16[];
@@ -134,6 +127,31 @@ typedef struct {
} PCD_DATABASE_INIT;
+typedef struct {
+ UINT32 Offset:24;
+ UINT32 Data:8;
+} PCD_DATABASE_SKU_DELTA_DATA;
+
+typedef struct {
+ SKU_ID SkuId;
+ SKU_ID SkuIdCompared;
+ UINT32 Length;
+ //PCD_DATABASE_SKU_DELTA_DATA DeltaData[]
+} PCD_DATABASE_SKU_DELTA;
+
+//
+// PCD database layout:
+// +---------------------------------+
+// | PCD_DATABASE_INIT (DEFAULT SKU) |
+// +---------------------------------+
+// | PCD_DATABASE_SKU_DELTA (SKU A) |
+// +---------------------------------+
+// | PCD_DATABASE_SKU_DELTA (SKU B) |
+// +---------------------------------+
+// | ...... |
+// +---------------------------------+
+//
+
//
// PEI and DXE Pcd driver use the same PCD database
//
--
2.7.0.windows.1
_______________________________________________
edk2-devel mailing list
edk2-devel@lists.01.org
https://lists.01.org/mailman/listinfo/edk2-devel
