Partitions API

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Overview

The esp_partition component has higher-level API functions which work with partitions defined in the partition table. These APIs are based on lower level API provided by SPI Flash driver.

Partition Table API

ESP-IDF projects use a partition table to maintain information about various regions of SPI flash memory (bootloader, various application binaries, data, filesystems). More information can be found in Partition Tables.

This component provides API functions to enumerate partitions found in the partition table and perform operations on them. These functions are declared in esp_partition.h:

See Also

API Reference - Partition Table

Header File

Functions

esp_partition_iterator_t esp_partition_find(esp_partition_type_t type, esp_partition_subtype_t subtype, const char *label)

Find partition based on one or more parameters.

Parameters

  • type – Partition type, one of esp_partition_type_t values or an 8-bit unsigned integer. To find all partitions, no matter the type, use ESP_PARTITION_TYPE_ANY, and set subtype argument to ESP_PARTITION_SUBTYPE_ANY.

  • subtype – Partition subtype, one of esp_partition_subtype_t values or an 8-bit unsigned integer. To find all partitions of given type, use ESP_PARTITION_SUBTYPE_ANY.

  • label – (optional) Partition label. Set this value if looking for partition with a specific name. Pass NULL otherwise.

Returns

iterator which can be used to enumerate all the partitions found, or NULL if no partitions were found. Iterator obtained through this function has to be released using esp_partition_iterator_release when not used any more.

const esp_partition_t *esp_partition_find_first(esp_partition_type_t type, esp_partition_subtype_t subtype, const char *label)

Find first partition based on one or more parameters.

Parameters

  • type – Partition type, one of esp_partition_type_t values or an 8-bit unsigned integer. To find all partitions, no matter the type, use ESP_PARTITION_TYPE_ANY, and set subtype argument to ESP_PARTITION_SUBTYPE_ANY.

  • subtype – Partition subtype, one of esp_partition_subtype_t values or an 8-bit unsigned integer To find all partitions of given type, use ESP_PARTITION_SUBTYPE_ANY.

  • label – (optional) Partition label. Set this value if looking for partition with a specific name. Pass NULL otherwise.

Returns

pointer to esp_partition_t structure, or NULL if no partition is found. This pointer is valid for the lifetime of the application.

const esp_partition_t *esp_partition_get(esp_partition_iterator_t iterator)

Get esp_partition_t structure for given partition.

Parameters

iterator – Iterator obtained using esp_partition_find. Must be non-NULL.

Returns

pointer to esp_partition_t structure. This pointer is valid for the lifetime of the application.

esp_partition_iterator_t esp_partition_next(esp_partition_iterator_t iterator)

Move partition iterator to the next partition found.

Any copies of the iterator will be invalid after this call.

Parameters

iterator – Iterator obtained using esp_partition_find. Must be non-NULL.

Returns

NULL if no partition was found, valid esp_partition_iterator_t otherwise.

void esp_partition_iterator_release(esp_partition_iterator_t iterator)

Release partition iterator.

Parameters

iterator – Iterator obtained using esp_partition_find. The iterator is allowed to be NULL, so it is not necessary to check its value before calling this function.

const esp_partition_t *esp_partition_verify(const esp_partition_t *partition)

Verify partition data.

Given a pointer to partition data, verify this partition exists in the partition table (all fields match.)

This function is also useful to take partition data which may be in a RAM buffer and convert it to a pointer to the permanent partition data stored in flash.

Pointers returned from this function can be compared directly to the address of any pointer returned from esp_partition_get(), as a test for equality.

Parameters

partition – Pointer to partition data to verify. Must be non-NULL. All fields of this structure must match the partition table entry in flash for this function to return a successful match.

Returns

  • If partition not found, returns NULL.

  • If found, returns a pointer to the esp_partition_t structure in flash. This pointer is always valid for the lifetime of the application.

esp_err_t esp_partition_read(const esp_partition_t *partition, size_t src_offset, void *dst, size_t size)

Read data from the partition.

Partitions marked with an encryption flag will automatically be be read and decrypted via a cache mapping.

Parameters

  • partition – Pointer to partition structure obtained using esp_partition_find_first or esp_partition_get. Must be non-NULL.

  • dst – Pointer to the buffer where data should be stored. Pointer must be non-NULL and buffer must be at least ‘size’ bytes long.

  • src_offset – Address of the data to be read, relative to the beginning of the partition.

  • size – Size of data to be read, in bytes.

Returns

ESP_OK, if data was read successfully; ESP_ERR_INVALID_ARG, if src_offset exceeds partition size; ESP_ERR_INVALID_SIZE, if read would go out of bounds of the partition; or one of error codes from lower-level flash driver.

esp_err_t esp_partition_write(const esp_partition_t *partition, size_t dst_offset, const void *src, size_t size)

Write data to the partition.

Before writing data to flash, corresponding region of flash needs to be erased. This can be done using esp_partition_erase_range function.

Partitions marked with an encryption flag will automatically be written via the esp_flash_write_encrypted() function. If writing to an encrypted partition, all write offsets and lengths must be multiples of 16 bytes. See the esp_flash_write_encrypted() function for more details. Unencrypted partitions do not have this restriction.

Note

Prior to writing to flash memory, make sure it has been erased with esp_partition_erase_range call.

Parameters

  • partition – Pointer to partition structure obtained using esp_partition_find_first or esp_partition_get. Must be non-NULL.

  • dst_offset – Address where the data should be written, relative to the beginning of the partition.

  • src – Pointer to the source buffer. Pointer must be non-NULL and buffer must be at least ‘size’ bytes long.

  • size – Size of data to be written, in bytes.

Returns

ESP_OK, if data was written successfully; ESP_ERR_INVALID_ARG, if dst_offset exceeds partition size; ESP_ERR_INVALID_SIZE, if write would go out of bounds of the partition; or one of error codes from lower-level flash driver.

esp_err_t esp_partition_read_raw(const esp_partition_t *partition, size_t src_offset, void *dst, size_t size)

Read data from the partition without any transformation/decryption.

Note

This function is essentially the same as esp_partition_read() above. It just never decrypts data but returns it as is.

Parameters

  • partition – Pointer to partition structure obtained using esp_partition_find_first or esp_partition_get. Must be non-NULL.

  • dst – Pointer to the buffer where data should be stored. Pointer must be non-NULL and buffer must be at least ‘size’ bytes long.

  • src_offset – Address of the data to be read, relative to the beginning of the partition.

  • size – Size of data to be read, in bytes.

Returns

ESP_OK, if data was read successfully; ESP_ERR_INVALID_ARG, if src_offset exceeds partition size; ESP_ERR_INVALID_SIZE, if read would go out of bounds of the partition; or one of error codes from lower-level flash driver.

esp_err_t esp_partition_write_raw(const esp_partition_t *partition, size_t dst_offset, const void *src, size_t size)

Write data to the partition without any transformation/encryption.

Before writing data to flash, corresponding region of flash needs to be erased. This can be done using esp_partition_erase_range function.

Note

This function is essentially the same as esp_partition_write() above. It just never encrypts data but writes it as is.

Note

Prior to writing to flash memory, make sure it has been erased with esp_partition_erase_range call.

Parameters

  • partition – Pointer to partition structure obtained using esp_partition_find_first or esp_partition_get. Must be non-NULL.

  • dst_offset – Address where the data should be written, relative to the beginning of the partition.

  • src – Pointer to the source buffer. Pointer must be non-NULL and buffer must be at least ‘size’ bytes long.

  • size – Size of data to be written, in bytes.

Returns

ESP_OK, if data was written successfully; ESP_ERR_INVALID_ARG, if dst_offset exceeds partition size; ESP_ERR_INVALID_SIZE, if write would go out of bounds of the partition; or one of the error codes from lower-level flash driver.

esp_err_t esp_partition_erase_range(const esp_partition_t *partition, size_t offset, size_t size)

Erase part of the partition.

Parameters

  • partition – Pointer to partition structure obtained using esp_partition_find_first or esp_partition_get. Must be non-NULL.

  • offset – Offset from the beginning of partition where erase operation should start. Must be aligned to partition->erase_size.

  • size – Size of the range which should be erased, in bytes. Must be divisible by partition->erase_size.

Returns

ESP_OK, if the range was erased successfully; ESP_ERR_INVALID_ARG, if iterator or dst are NULL; ESP_ERR_INVALID_SIZE, if erase would go out of bounds of the partition; or one of error codes from lower-level flash driver.

esp_err_t esp_partition_mmap(const esp_partition_t *partition, size_t offset, size_t size, esp_partition_mmap_memory_t memory, const void **out_ptr, esp_partition_mmap_handle_t *out_handle)

Configure MMU to map partition into data memory.

Unlike spi_flash_mmap function, which requires a 64kB aligned base address, this function doesn’t impose such a requirement. If offset results in a flash address which is not aligned to 64kB boundary, address will be rounded to the lower 64kB boundary, so that mapped region includes requested range. Pointer returned via out_ptr argument will be adjusted to point to the requested offset (not necessarily to the beginning of mmap-ed region).

To release mapped memory, pass handle returned via out_handle argument to esp_partition_munmap function.

Parameters

  • partition – Pointer to partition structure obtained using esp_partition_find_first or esp_partition_get. Must be non-NULL.

  • offset – Offset from the beginning of partition where mapping should start.

  • size – Size of the area to be mapped.

  • memory – Memory space where the region should be mapped

  • out_ptr – Output, pointer to the mapped memory region

  • out_handle – Output, handle which should be used for esp_partition_munmap call

Returns

ESP_OK, if successful

void esp_partition_munmap(esp_partition_mmap_handle_t handle)

Release region previously obtained using esp_partition_mmap.

Note

Calling this function will not necessarily unmap memory region. Region will only be unmapped when there are no other handles which reference this region. In case of partially overlapping regions it is possible that memory will be unmapped partially.

Parameters

handle – Handle obtained from spi_flash_mmap

esp_err_t esp_partition_get_sha256(const esp_partition_t *partition, uint8_t *sha_256)

Get SHA-256 digest for required partition.

For apps with SHA-256 appended to the app image, the result is the appended SHA-256 value for the app image content. The hash is verified before returning, if app content is invalid then the function returns ESP_ERR_IMAGE_INVALID. For apps without SHA-256 appended to the image, the result is the SHA-256 of all bytes in the app image. For other partition types, the result is the SHA-256 of the entire partition.

Parameters

  • partition – [in] Pointer to info for partition containing app or data. (fields: address, size and type, are required to be filled).

  • sha_256 – [out] Returned SHA-256 digest for a given partition.

Returns

  • ESP_OK: In case of successful operation.

  • ESP_ERR_INVALID_ARG: The size was 0 or the sha_256 was NULL.

  • ESP_ERR_NO_MEM: Cannot allocate memory for sha256 operation.

  • ESP_ERR_IMAGE_INVALID: App partition doesn’t contain a valid app image.

  • ESP_FAIL: An allocation error occurred.

bool esp_partition_check_identity(const esp_partition_t *partition_1, const esp_partition_t *partition_2)

Check for the identity of two partitions by SHA-256 digest.

Parameters

  • partition_1 – [in] Pointer to info for partition 1 containing app or data. (fields: address, size and type, are required to be filled).

  • partition_2 – [in] Pointer to info for partition 2 containing app or data. (fields: address, size and type, are required to be filled).

Returns

  • True: In case of the two firmware is equal.

  • False: Otherwise

esp_err_t esp_partition_register_external(esp_flash_t *flash_chip, size_t offset, size_t size, const char *label, esp_partition_type_t type, esp_partition_subtype_t subtype, const esp_partition_t **out_partition)

Register a partition on an external flash chip.

This API allows designating certain areas of external flash chips (identified by the esp_flash_t structure) as partitions. This allows using them with components which access SPI flash through the esp_partition API.

Parameters

  • flash_chip – Pointer to the structure identifying the flash chip

  • offset – Address in bytes, where the partition starts

  • size – Size of the partition in bytes

  • label – Partition name

  • type – One of the partition types (ESP_PARTITION_TYPE_*), or an integer. Note that applications can not be booted from external flash chips, so using ESP_PARTITION_TYPE_APP is not supported.

  • subtype – One of the partition subtypes (ESP_PARTITION_SUBTYPE_*), or an integer.

  • out_partition – [out] Output, if non-NULL, receives the pointer to the resulting esp_partition_t structure

Returns

  • ESP_OK on success

  • ESP_ERR_NO_MEM if memory allocation has failed

  • ESP_ERR_INVALID_ARG if the new partition overlaps another partition on the same flash chip

  • ESP_ERR_INVALID_SIZE if the partition doesn’t fit into the flash chip size

esp_err_t esp_partition_deregister_external(const esp_partition_t *partition)

Deregister the partition previously registered using esp_partition_register_external.

Parameters

partition – pointer to the partition structure obtained from esp_partition_register_external,

Returns

  • ESP_OK on success

  • ESP_ERR_NOT_FOUND if the partition pointer is not found

  • ESP_ERR_INVALID_ARG if the partition comes from the partition table

  • ESP_ERR_INVALID_ARG if the partition was not registered using esp_partition_register_external function.

Structures

struct esp_partition_t

partition information structure

This is not the format in flash, that format is esp_partition_info_t.

However, this is the format used by this API.

Public Members

esp_flash_t *flash_chip

SPI flash chip on which the partition resides

esp_partition_type_t type

partition type (app/data)

esp_partition_subtype_t subtype

partition subtype

uint32_t address

starting address of the partition in flash

uint32_t size

size of the partition, in bytes

uint32_t erase_size

size the erase operation should be aligned to

char label[17]

partition label, zero-terminated ASCII string

bool encrypted

flag is set to true if partition is encrypted

Macros

ESP_PARTITION_SUBTYPE_OTA(i)

Convenience macro to get esp_partition_subtype_t value for the i-th OTA partition.

Type Definitions

typedef uint32_t esp_partition_mmap_handle_t

Opaque handle for memory region obtained from esp_partition_mmap.

typedef struct esp_partition_iterator_opaque_ *esp_partition_iterator_t

Opaque partition iterator type.

Enumerations

enum esp_partition_mmap_memory_t

Enumeration which specifies memory space requested in an mmap call.

Values:

enumerator ESP_PARTITION_MMAP_DATA

map to data memory (Vaddr0), allows byte-aligned access, 4 MB total

enumerator ESP_PARTITION_MMAP_INST

map to instruction memory (Vaddr1-3), allows only 4-byte-aligned access, 11 MB total

enum esp_partition_type_t

Partition type.

Note

Partition types with integer value 0x00-0x3F are reserved for partition types defined by ESP-IDF. Any other integer value 0x40-0xFE can be used by individual applications, without restriction.

Values:

enumerator ESP_PARTITION_TYPE_APP

Application partition type.

enumerator ESP_PARTITION_TYPE_DATA

Data partition type.

enumerator ESP_PARTITION_TYPE_ANY

Used to search for partitions with any type.

enum esp_partition_subtype_t

Partition subtype.

Application-defined partition types (0x40-0xFE) can set any numeric subtype value.

Note

These ESP-IDF-defined partition subtypes apply to partitions of type ESP_PARTITION_TYPE_APP and ESP_PARTITION_TYPE_DATA.

Values:

enumerator ESP_PARTITION_SUBTYPE_APP_FACTORY

Factory application partition.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_MIN

Base for OTA partition subtypes.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_0

OTA partition 0.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_1

OTA partition 1.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_2

OTA partition 2.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_3

OTA partition 3.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_4

OTA partition 4.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_5

OTA partition 5.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_6

OTA partition 6.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_7

OTA partition 7.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_8

OTA partition 8.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_9

OTA partition 9.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_10

OTA partition 10.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_11

OTA partition 11.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_12

OTA partition 12.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_13

OTA partition 13.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_14

OTA partition 14.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_15

OTA partition 15.

enumerator ESP_PARTITION_SUBTYPE_APP_OTA_MAX

Max subtype of OTA partition.

enumerator ESP_PARTITION_SUBTYPE_APP_TEST

Test application partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_OTA

OTA selection partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_PHY

PHY init data partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_NVS

NVS partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_COREDUMP

COREDUMP partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_NVS_KEYS

Partition for NVS keys.

enumerator ESP_PARTITION_SUBTYPE_DATA_EFUSE_EM

Partition for emulate eFuse bits.

enumerator ESP_PARTITION_SUBTYPE_DATA_UNDEFINED

Undefined (or unspecified) data partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_ESPHTTPD

ESPHTTPD partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_FAT

FAT partition.

enumerator ESP_PARTITION_SUBTYPE_DATA_SPIFFS

SPIFFS partition.

enumerator ESP_PARTITION_SUBTYPE_ANY

Used to search for partitions with any subtype.

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