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PrmPkg: Add ALLOCATE_CONTEXT_BUFFER_IN_FW build option

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There's currently two approaches being considered for how to allocate the
context buffer passed to PRM handlers:

1. The context buffer is allocated and populated in firmware. As such, the
   FW converts all pointers internal to the buffer to virtual memory
   addresses at the virtual address change event. A single context buffer
   pointer is given to the OS via the PRM ACPI table and the OS converts
   this single physical address to a virtual address when it passes the
   context buffer as a pointer to PRM handlers.

2. The context buffer is allocated and populated in the OS. The OS gets
   all the information needed to populate the context buffer from other
   pre-existing resources (mainly physical addresses in the PRM ACPI
   table). The OS converts all the physical addresses to virtual addresses,
   allocates the context buffer instances, and fills in the information.
   The OS passes the context buffer virtual address to PRM handlers.

The prior behavior was (1). The current POR behavior has moved to (2).
Until (2) is used more widely, it can be kept around with fairly minimal
overhead via a build flag in a few places.

So the default behavior is now (2) (the expected permanent behavior) with
(1) easily enabled by defining "ALLOCATE_CONTEXT_BUFFER_IN_FW" in the
compiler defined macros. A DSC define was added in PrmPkg.dsc to set this
compiler macro in the package  build.

At some point in the future, all code (and some peripheral code)
surrounded with this build flag can be removed if (2) is fully
decided upon.

Cc: Andrew Fish <afish@apple.com>
Cc: Kang Gao <kang.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Benjamin You <benjamin.you@intel.com>
Cc: Liu Yun <yun.y.liu@intel.com>
Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Acked-by: Michael D Kinney <michael.d.kinney@intel.com>
Acked-by: Liming Gao <gaoliming@byosoft.com.cn>
Acked-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Ankit Sinha <ankit.sinha@intel.com>
This commit is contained in:
Michael Kubacki
2020-04-13 16:38:19 -07:00
committed by mergify[bot]
parent d2cb6e67a4
commit e846797662
6 changed files with 76 additions and 18 deletions
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4
PrmPkg/PrmLoaderDxe/PrmAcpiTable.h
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@@ -30,8 +30,10 @@ typedef struct {
UINT16 StructureLength; ///< Length in bytes of this structure
GUID Identifier; ///< GUID of the PRM handler for this structure
UINT64 PhysicalAddress; ///< Physical address of this PRM handler
#ifdef ALLOCATE_CONTEXT_BUFFER_IN_FW
UINT64 PrmContextBuffer; ///< Physical address of the context buffer for this
///< PRM handler (PRM_CONTEXT_BUFFER *)
#else
UINT64 StaticDataBuffer; ///< Physical address of the static data buffer for
///< this PRM handler (PRM_DATA_BUFFER *)
UINT64 AcpiParameterBuffer; ///< Physical address of the parameter buffer
@@ -39,6 +41,8 @@ typedef struct {
///< that is only used in the case of _DSM invocation.
///< If _DSM invocation is not used, this value is
///< ignored.
#endif
} PRM_HANDLER_INFORMATION_STRUCT;
typedef struct {