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== Article purpose == | == Article purpose == | ||
The '''Reserved-memory''' mechanism<ref>https://www.kernel.org/doc/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt</ref> allows reserving memory regions in the kernel. This mechanism is used by drivers to allocate buffers in specific memory regions (such as [[ | The '''Reserved-memory''' mechanism<ref>https://www.kernel.org/doc/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt</ref> allows reserving memory regions in the kernel. This mechanism is used by drivers to allocate buffers in specific memory regions (such as internal SRAM<ref name="SRAM">[[STM32MP13 SRAM internal memory]]</ref><ref name="MCU SRAM">[[MCU SRAM internal memory]]</ref>) or to get a dedicated memory pool that will not be managed by Linux<sup>®</sup> conventionnal memory allocator (in [[DDRCTRL and DDRPHYC internal peripherals|DDR]]).<br /> | ||
== Use cases == | == Use cases == | ||
In | In OpenSTLinux, the '''reserved-memory''' is used: | ||
* the [[Dmaengine overview|dmaengine driver]] to reserve the region where [[DMA internal peripheral|DMA]] buffers are allocated, typically | * On {{MicroprocessorDevice | device=1}} by: | ||
* the [[Linux remoteproc framework overview|remoteproc driver]] to reserve the regions in [[RETRAM internal memory|RETRAM]] and [[MCU SRAM internal memory|MCU SRAM]] where the coprocessor firmware will be loaded. | :* the [[Dmaengine overview|dmaengine driver]] to reserve the region where [[DMA internal peripheral|DMA]] buffers are allocated, typically internal SRAM<ref name="SRAM"/><ref name="MCU SRAM"/>. | ||
* the [[Linux_RPMsg_framework_overview|RPMsg driver]] to reserve the region where [[Linux RPMsg framework overview|RPMsg]] buffers used for interprocess communication with the coprocessor, are allocated, typically [[MCU SRAM internal memory|MCU SRAM]]. | * On {{MicroprocessorDevice | device=15}} by: | ||
* the Vivante Gcnano driver to reserve the region where the GPU working memory is allocated, typically the [[DDRCTRL and DDRPHYC internal peripherals|DDR]]. | :* the [[Linux remoteproc framework overview|remoteproc driver]] to reserve the regions in [[RETRAM internal memory|RETRAM]] and [[MCU SRAM internal memory|MCU SRAM]] where the coprocessor firmware will be loaded. | ||
:* the [[Linux_RPMsg_framework_overview|RPMsg driver]] to reserve the region where [[Linux RPMsg framework overview|RPMsg]] buffers used for interprocess communication with the coprocessor, are allocated, typically [[MCU SRAM internal memory|MCU SRAM]]. | |||
:* the Vivante Gcnano driver to reserve the region where the GPU working memory is allocated, typically the [[DDRCTRL and DDRPHYC internal peripherals|DDR]]. | |||
== References == | == References == | ||
Revision as of 16:02, 4 November 2021
1. Article purpose
The Reserved-memory mechanism[1] allows reserving memory regions in the kernel. This mechanism is used by drivers to allocate buffers in specific memory regions (such as internal SRAM[2][3]) or to get a dedicated memory pool that will not be managed by Linux® conventionnal memory allocator (in DDR).
2. Use cases
In OpenSTLinux, the reserved-memory is used:
- On STM32MP1 series by:
- the dmaengine driver to reserve the region where DMA buffers are allocated, typically internal SRAM[2][3].
- On STM32MP15x lines
by:
- the remoteproc driver to reserve the regions in RETRAM and MCU SRAM where the coprocessor firmware will be loaded.
- the RPMsg driver to reserve the region where RPMsg buffers used for interprocess communication with the coprocessor, are allocated, typically MCU SRAM.
- the Vivante Gcnano driver to reserve the region where the GPU working memory is allocated, typically the DDR.
3. References