View source for STM32 MPU Flash mapping

{{ApplicableFor
|MPUs list=STM32MP13x, STM32MP15x
|MPUs checklist=STM32MP13x, STM32MP15x
}}
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== Supported Flash memory technologies ==
{{MicroprocessorDevice | device=1}} support the following types of Flash memory and the sub-bullets below show which interfaces are supported on STMicroelectronics boards:
* SD card on the SDMMC interface
:* used on [[:Category:Getting started with STM32MP1 boards|STM32MP13 DISCO board]]
:* used on [[:Category:Getting started with STM32MP1 boards|STM32MP15 EVAL board]]
:* used on [[:Category:Getting started with STM32MP1 boards|STM32MP15 DISCO board]]
* ''e''•MMC on the SDMMC interface
:* used on [[:Category:Getting started with STM32MP1 boards|STM32MP15 EVAL board]] only
* Serial NOR Flash memory on the Dual QSPI interface
:* used on [[:Category:Getting started with STM32MP1 boards|STM32MP15 EVAL board]] only
* NAND Flash memory on the FMC interface
:* used on [[:Category:Getting started with STM32MP1 boards|STM32MP15 EVAL board]] only.
The next section lists all partitions used on STM32MP1 boards (size, name, and content), and the following sections show how they are mapped on the different types of Flash memory.

== Flash partitions ==
The tables below list the partitions defined for STMP32MP1 boards and gives typical sizes with OpenSTLinux, that can be tuned, depending on the targeted application needs.
<br>
{| class="st-table"
|-
! Size !! Component !! Comment
|-
| Remaining area || userfs || The user file system contains user data and examples
|-
| 768 Mbytes || rootfs || Linux root file system contains all user space binaries (executable, libraries, and so on), and kernel modules 
|-
| 16 Mbytes || vendorfs || This partition is preferred to the rootfs for third-party proprietary binaries, and ensures that they are not contaminated by any open source licence, such as GPL v3
|- 
| 64 Mbytes || bootfs<br>or<br>boot (NAND)|| The boot file system contains:
* (option) the init RAM file system, which can be copied to the external RAM and used by Linux before mounting a fatter rootfs
* Linux kernel device tree (can be in a Flattened Image Tree - FIT)
* Linux kernel U-Boot image (can be in a Flattened Image Tree - FIT)
* For all flashes except for NOR: the boot loader splash screen image, displayed by U-Boot
* [[U-Boot_overview#Generic_Distro_configuration|U-Boot distro config file]] ''extlinux.conf''
|-
| 2 * 256 Kbytes (*) || u-boot-env<br>or uboot_config / uboot_config_r (NAND) || This partition is used to store the U-Boot environment.<br>uboot_config_r is used for redundancy management with uboot_config, in NAND Flash.
|-
| 4 Mbytes || fip  || The [[TF-A_overview#FIP|TF-A firmware image package (FIP)]] is a binary file that encapsulates several binaries, and their certificates (optionally, for authentication), that will be loaded by TF-A BL2.<br>
OpenSTLinux FIP contains:
* the second stage boot loader (SSBL):
** U-Boot binary
** U-Boot device tree blob
* the OP-TEE
* the [[How_to_configure_TF-A_FW_CONFIG|firmware configuration file]] used by TF-A BL2
There are two partitions, fip-a and fip-b, when A/B (seamless) FIP firmware update is activated in TF-A BL2.
|-
| 256 Kbytes to 512 Kbytes (*) || metadata || Metadata are used by TF-A BL2 to localize the FIP version to use, when the FIP is subject to firmware update.
Notes:
* The metadata are not used when the FIP firmware update is not activated in TF-A BL2; these partitions can be removed or left empty in this case.
* The metadata update is failsafe against power loss during the FIP update process with two copies.
|-
| 256 Kbytes to 512 Kbytes (*) || fsbl || The first stage boot loader is Arm Trusted Firmware ([[TF-A_overview#BL2|TF-A]]). At least two copies are embedded.<br>
Notes:
* The FSBL payload is limited to 128 Kbytes on STM32MP13 and 247 Kbytes on STM32MP15.
* The TF-A BL2 update is failsafe against power loss during the process with two copies.
|}
(*): The partition size depends on the Flash technology, to be aligned to the block erase size of the Flash memory present on the board: NOR (256 Kbytes) / NAND (512 Kbytes).
{{Info | Some boards can be equipped with multiple Flash devices, like the [[:Category:Getting started with STM32MP1 boards|STM32MP15 EVAL board]], where all of the Flash devices can be programmed with [[STM32CubeProgrammer]]. However, caution must be taken for the serial NOR/NAND and SLC NAND because a '''static bootable MTD partitioning''' is defined in U-Boot default config (see [[How_to_configure_U-Boot_for_your_board#MTD_partitions|MTD configuration ]] for details), with the consequence that up to 6 Mbytes of space is lost at the beginning of each such device, '''even those which are not bootable'''.}}

== SD card memory mapping ==
The SD card has to be partitioned with GPT format in order to be recognized by the STM32MP1. The easiest way to achieve this is to use [[STM32CubeProgrammer]].<br />
The ROM code looks for the GPT entries whose name begins with "fsbl": fsbl1 and fsbl2 for example.<br/>
Note: The SD card can be unplugged from the board and inserted into a Linux host computer for direct partitioning with Linux utilities and access to the '''bootfs''', '''rootfs''' and '''userfs''' partitions. The file system is Linux EXT4.
[[Image:SD card mapping.png|center|link=]]

== ''e''•MMC memory mapping ==
The ''e''•MMC embeds four physical partitions:
* Boot area partition 1: one copy of the FSBL
* Boot area partition 2: one copy of the FSBL
* User data area: formatted with GPT partitioning and used to store all remaining partitions
* Replay Protected Memory Block (RPMB): not shown in the figure below, since not involved in the current boot chain.
[[STM32CubeProgrammer]] has to be used to prepare the ''e''•MMC with the layout shown below, and to populate each partition.
{{Info | The boot area partition used by the ''e''•MMC boot sequence is selected via the EXT_CSD[179] register in the ''e''•MMC. The [[STM32CubeProgrammer]] execution is concluded with the selection of the last written partition from the flashlayout file, typically partition 2. The other copy is never used as long as the user does not explicitly change the ''e''•MMC EXT_CSD[179] register to select it.}}
[[File:eMMC mapping.png|center|link=]]

== NOR memory mapping ==
As NOR Flash memory is expensive, its size is usually limited to the minimum needed to store only the bootloaders. The system files (bootfs, rootfs and userfs) are usually stored in another Flash  memory, such as the SD card in OpenSTLinux distribution.<br /> [[STM32CubeProgrammer]] must be used to prepare the NOR Flash and the SD card with the layout shown below, and to populate each partition.<br /><br>
[[File:NOR mapping.png|center|link=]]

It is possible to use an ''e''•MMC card or NAND  as second-level Flash memory, rather than an SD card. This requires the following aspects to be changed:
* The Flash memory layout, using [[STM32CubeProgrammer]] in order to write the rootfs and userfs to the targeted Flash memory
* The Linux kernel parameters, using [[U-Boot overview|U-Boot]], in order to indicate where the rootfs and userfs have to be mounted.

== NAND memory mapping ==
[[STM32CubeProgrammer]] has to be used to prepare the NAND Flash memory with the layout shown below, and to populate each partition.<br />
[[File:NAND mapping.png|center|link=]]
{{Warning|In the '''RAW/MTD area''', the number of copies to embed and the number of blocks to reserve at the end of each partition, for future bad blocks replacement, are a critical part of NAND based product dimensioning !<br>
The strategy has to take into account many parameters such as:
* the binaries sizes,
* the read accesses to those partitions during product life, that may generate read disturb effect,
* the capability of the product to refresh the partitions content when erroneous bits are detected,
* the number of software updates estimated on this partition,
* the selected NAND flash characteristics
ST set foundations in the STM32MP1 device in order to allow the integration of NAND flash memories but the product definition remains the customer responsibility. Please, contact your memory provider for further advice.}}
<noinclude>
[[Category:Platform configuration]]
{{PublicationRequestId | 14615 | 2020-01-15 |}}
</noinclude>