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- Make footer copyright year update automatically - Add clarification about EPLD region - Add heading to build tool doc - Clean up warnings about section links, length of underlines, etc. - Adjust whitespace in Build System doc - Fix reference to key management section Signed-off-by: Atharva Lele <atharva.lele@intel.com>
153 lines
6.5 KiB
ReStructuredText
Executable File
153 lines
6.5 KiB
ReStructuredText
Executable File
Memory Map
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------------
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Temporary Memory Layout
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^^^^^^^^^^^^^^^^^^^^^^^
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|SPN| Stage 1 temporary memory layout::
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Temporary Memory
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+------------------------------+ Top of 4GB
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| Memory Mapped Flash |
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+------------------------------+ Memory-Mapped Flash Base
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| FSP-T Reserved Data |
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+------------------------------+ Top of Usable Temporary Memory
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| Available* |
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+------------------------------+ End of Stage 1 Data
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| Stage 1 Data |
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+------------------------------+ Stage 1 Stack Top/Stage 1 Data Base
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| Stage 1 Stack |
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+------------------------------+ Usable CAR Base/Stage 1 Stack Base
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.. [*] FSP-M Stack Region is typically chosen from Available Temporary Memory.
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Memory Management
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^^^^^^^^^^^^^^^^^
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* Once main memory has been initialized, Stage 1B migrates the Slim Bootloader stack from temporary memory to the permanent
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memory and also reserves a portion of memory to be used for global data structures (``LdrGlobal``, GDT, IDT), stack, heap,
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and payload.
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Permanent Memory Map
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^^^^^^^^^^^^^^^^^^^^
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|SPN| internal memory map layout (``BootloaderCoreLib.h``)::
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Reserved MEM
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+------------------------------+ Top of Low MEM
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| SOC Reserved MEM |
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+------------------------------+ Top of usable MEM Base
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| FSP Reserved MEM |
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+------------------------------+ FSP Reserved MEM Base
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| LDR Reserved MEM |
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+------------------------------+ LDR Reserved MEM Base
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| ACPI NVS MEM |
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+------------------------------+ ACPI NVS MEM Base
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| ACPI Reclaim MEM |
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+------------------------------+ ACPI Reclaim MEM Base
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| PLD Reserved MEM |
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+------------------------------+ PLD Reserved MEM Base
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Loader Reserved MEM
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+------------------------------+ StackTop
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| LDR Stack (Down) |
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| LDR HOB (Up) |
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+------------------------------+ MemPoolEnd (Fixed)
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| Global Data structures | |
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+------------------------------+ |
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| Permanent MEM Pool (Down) | |
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+------------------------------+ MemPoolCurrTop (Moving down)
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+------------------------------+ MemPoolCurrBottom (Moving up)
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| | ^
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| Temporary MEM Pool (Up) | |
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+------------------------------+ MemPoolStart (Fixed)
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Memory Allocation within Slim Bootloader
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Slim Bootloader has two different libraries for allocating memory during various
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execution phases of the bootloader.
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* Stage 1A, Stage 1B, Stage 2 use ``MemoryAllocationLib`` present in ``BootloaderCorePkg``.
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* OsLoader and FwUpdate use ``FullMemoryAllocationLib`` present in ``BootloaderCommonPkg``.
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``MemoryAllocationLib``
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~~~~~~~~~~~~~~~~~~~~~~~
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``MemoryAllocationLib`` allocates memory from the Loader Reserved Memory region. This
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can be seen diagrammatically in the "Loader Reserved MEM" layout shown above.
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``MemoryAllocationLib`` provides services for allocating two different types of memory -
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* Bootloader permanent memory:
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* Bootloader permanent memory is used by the bootloader to store device tables, S3 Data,
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SBL container headers, etc.
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* Memory allocated from bootloader permanent memory region cannot be freed
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* Note that permanent memory does not mean that it is persistent across reboots
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* ``AllocatePool()``, ``AllocateZeroPool()``, ``AllocatePages()``, ``AllocateAlignedPages()``
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allocate memory from the Loader Reserved region starting from ``MemPoolEnd`` which grows
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down towards ``MemPoolStart``
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* Currently used allocated memory is between ``MemPoolEnd`` and ``MemPoolCurrTop``
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* Loader Reserved Memory is reported to the OS as "Reserved" memory
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* Temporary Memory:
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* Temporary memory requested by a stage is expected to be used by that stage itself
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* Temporary memory is allocated starting from ``MemPoolStart`` and grows up towards
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``MemPoolEnd``.
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* Currently used temporary memory is between ``MemPoolStart`` and ``MemPoolEnd``
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* Temporary Memory is freed by the ``FreeTemporaryMemory()`` API call.
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* Calling ``FreeTemporaryMemory()`` with ``NULL`` as a parameter will free all allocated
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memory within the temporary memory region.
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``FullMemoryAllocationLib``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* Stage 2 passes the HOB list pointer, and the Payload executable base to the payload.
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* The HOB list pointer contains the pointer to the HOBs consumed by the payload. The ``MEMORY_MAP_INFO`` HOB will report memory available to the payload.
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* The payload reserved memory region from memory map info hob is identified by the ``MEM_MAP_TYPE_RESERVED`` entry type and the ``MEM_MAP_FLAG_PAYLOAD``
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flag.
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* In case of tightly-coupled payloads, once the payload is loaded, ``PayloadInit()`` is called by ``PayloadEntryLib`` to initialize global data for the
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payload.
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* ``PayloadInit()`` in turn calls ``AddMemoryResourceRange()`` from ``FullMemoryAllocationLib`` to initialize the memory ranges from which memory
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will be allocated to the payload.
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* The size of the reserved memory, heap, and stack is determined by their respective PCDs defined in ``BoardConfig.py``.
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* ``PLD_RSVD_MEM_SIZE``, ``PLD_HEAP_SIZE``, and ``PLD_STACK_SIZE``
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* Once the memory ranges are initialized, dynamic memory allocation will be done from the payload heap region.
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* The memory map of the Payload can be seen below:
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.. code-block:: text
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Payload Memmap
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+--------------------------------------------+ TOLUM
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| Reserved memory for Slimboot core |
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+--------------------------------------------+ RsvdBase + RsvdSize
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| Reserved memory for Payload |
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+--------------------------------------------+ RsvdBase
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| + DMA buffer |
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+--------------------------------------------+ DmaBase
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| + Payload heap |
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+--------------------------------------------+ HeapBase
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| + Payload stack |
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+--------------------------------------------+ StackBase
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| Free memory |
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+--------------------------------------------+ 0
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