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Merge branch 'docs/add_flash_to_psram_feature' into 'master'

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docs: add the flash content moved to psram feature

Closes IDF-5885

See merge request espressif/esp-idf!19908
This commit is contained in:
Wan Lei
2022-10-17 14:51:15 +08:00
parent faff090d5a 76eef386bb
commit f98a37f571
10 changed files with 113 additions and 31 deletions
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59
docs/en/api-guides/external-ram.rst
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@@ -41,13 +41,17 @@ ESP-IDF fully supports the use of external RAM in applications. Once the externa
* :ref:`external_ram_config_memory_map`
* :ref:`external_ram_config_capability_allocator`
* :ref:`external_ram_config_malloc` (default)
:esp32 or esp32s2: * :ref:`external_ram_config_bss`
* :ref:`external_ram_config_bss`
:esp32: * :ref:`external_ram_config_noinit`
:esp32s2 or esp32s3: * :ref:`external_ram_config_instructions`
:esp32s2 or esp32s3: * :ref:`external_ram_config_rodata`
.. _external_ram_config_memory_map:
Integrate RAM into the {IDF_TARGET_NAME} Memory Map
---------------------------------------------------
{IDF_TARGET_PSRAM_ADDR_START:default="Value not updated", esp32="0x3F800000", esp32s2="0x3F500000", esp32s3="0x3D000000"}
Select this option by choosing "Integrate RAM into memory map" from :ref:`CONFIG_SPIRAM_USE`.
@@ -91,25 +95,22 @@ If a suitable block of preferred internal/external memory is not available, the
Because some buffers can only be allocated in internal memory, a second configuration item :ref:`CONFIG_SPIRAM_MALLOC_RESERVE_INTERNAL` defines a pool of internal memory which is reserved for *only* explicitly internal allocations (such as memory for DMA use). Regular ``malloc()`` will not allocate from this pool. The :ref:`MALLOC_CAP_DMA <dma-capable-memory>` and ``MALLOC_CAP_INTERNAL`` flags can be used to allocate memory from this pool.
.. only:: SOC_SPIRAM_SUPPORTED
.. _external_ram_config_bss:
.. _external_ram_config_bss:
Allow .bss Segment to be Placed in External Memory
--------------------------------------------------
Allow .bss Segment to be Placed in External Memory
-------------------------------------------------------
Enable this option by checking :ref:`CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY`.
Enable this option by checking :ref:`CONFIG_SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY`. This configuration setting is independent of the other three.
If enabled, a region of the address space starting from {IDF_TARGET_PSRAM_ADDR_START} will be used to store zero-initialized data (BSS segment) from the lwIP, net80211, libpp, and bluedroid ESP-IDF libraries.
If enabled, a region of the address space starting from {IDF_TARGET_PSRAM_ADDR_START} will be used to store zero-initialized data (BSS segment) from the lwIP, net80211, libpp, and bluedroid ESP-IDF libraries.
Additional data can be moved from the internal BSS segment to external RAM by applying the macro ``EXT_RAM_BSS_ATTR`` to any static declaration (which is not initialized to a non-zero value).
Additional data can be moved from the internal BSS segment to external RAM by applying the macro ``EXT_RAM_BSS_ATTR`` to any static declaration (which is not initialized to a non-zero value).
It is also possible to place the BSS section of a component or a library to external RAM using linker fragment scheme ``extram_bss``.
It is also possible to place the BSS section of a component or a library to external RAM using linker fragment scheme ``extram_bss``.
This option reduces the internal static memory used by the BSS segment.
Remaining external RAM can also be added to the capability heap allocator using the method shown above.
This option reduces the internal static memory used by the BSS segment.
Remaining external RAM can also be added to the capability heap allocator using the method shown above.
.. only:: esp32
@@ -122,6 +123,38 @@ Because some buffers can only be allocated in internal memory, a second configur
By applying the macro ``EXT_RAM_NOINIT_ATTR``, data could be moved from the internal NOINIT segment to external RAM. Remaining external RAM can still be added to the capability heap allocator using the method shown above, :ref:`external_ram_config_capability_allocator`.
.. only:: SOC_SPIRAM_XIP_SUPPORTED
.. _external_ram_config_instructions:
Move Instructions in Flash to PSRAM
-----------------------------------
The :ref:`CONFIG_SPIRAM_FETCH_INSTRUCTIONS` option allows the flash ``.text`` sections (use for instructions) to be placed in PSRAM.
By enabling the :ref:`CONFIG_SPIRAM_FETCH_INSTRUCTIONS` option
- Instructions from the ``.text`` sections of flash are moved into PSRAM on system startup.
- The corresponding virtual memory range of those instructions will also be re-mapped to PSRAM.
If :ref:`CONFIG_SPIRAM_RODATA` is also enabled, the Cache won't be disabled during an SPI1 Flash operation. You don't need to make sure ISRs, ISR callbacks and involved data are placed in internal RAM, thus internal RAM usage can be optimized.
.. _external_ram_config_rodata:
Move Read-Only Data in Flash to PSRAM
---------------------------------------
The :ref:`CONFIG_SPIRAM_RODATA` option allows the flash ``.rodata`` sections (use for read only data) to be placed in PSRAM.
By enabling the :ref:`CONFIG_SPIRAM_RODATA` option
- Instructions from the ``.rodata`` sections of flash are moved into PSRAM on system startup.
- The corresponding virtual memory range of those rodata will also be re-mapped to PSRAM.
If :ref:`CONFIG_SPIRAM_FETCH_INSTRUCTIONS` is also enabled, the Cache won't be disabled during an SPI1 Flash operation. You don't need to make sure ISRs, ISR callbacks and involved data are placed in internal RAM, thus internal RAM usage can be optimized.
Restrictions
============