Espressif ESP32-S2 Programming Manual page 1462

Chapter 4. API Guides
• CONFIG_MBEDTLS_ECP_C
listed in the sub-menu.)
• CONFIG_MBEDTLS_SSL_RENEGOTIATION
• Change CONFIG_MBEDTLS_TLS_MODE
• Consider disabling some ciphersuites listed in the "TLS Key Exchange Methods"sub-menu (i.e.
FIG_MBEDTLS_KEY_EXCHANGE_RSA)
The help text for each option has some more information.
Important: It is strongly not recommended to disable all these mbedTLS options. Only disable options where
you understand the functionality and are certain that it is not needed in the application. In particular:
• Ensure that any TLS server(s) the device connects to can still be used. If the server is controlled by a third
party or a cloud service, recommend ensuring that the firmware supports at least two of the supported cipher
suites in case one is disabled in a future update.
• Ensure that any TLS client(s) that connect to the device can still connect with supported/recommended cipher
suites. Note that future versions of client operating systems may remove support for some features, so it is
recommended to enable multiple supported cipher suites or algorithms for redundancy.
If depending on third party clients or servers, always pay attention to announcements about future changes to sup-
ported TLS features. If not, the ESP32-S2 device may become inaccessible if support changes.
Note: Not every combination of mbedTLS compile-time config is tested in ESP-IDF. If you find a combination that
fails to compile or function as expected, please report the details on GitHub.
FreeModBus If using
FIG_FMB_COMM_MODE_RTU_EN,
functionality.
VFS Virtual filesystem feature in ESP-IDF allows multiple filesystem drivers and file-like peripheral drivers to
be accessed using standard I/O functions (open, read, write, etc.) and C library functions (fopen, fread,
fwrite, etc.). When filesystem or file-like peripheral driver functionality is not used in the application this feature
can be fully or partially disabled. VFS component provides the following configuration options:
• CONFIG_VFS_SUPPORT_TERMIOS
functions. Currently, these functions are implemented only for UART VFS driver. Most applications can
disable this option. Disabling this option reduces the code size by about 1.8 kB.
• CONFIG_VFS_SUPPORT_SELECT
file descriptors. Currently, only the UART and eventfd VFS drivers implement select support. Note that
when this option is disabled, select can still be used for socket file descriptors. Disabling this option reduces
the code size by about 2.7 kB.
• CONFIG_VFS_SUPPORT_DIR
such as readdir (see the description of this option for the complete list). Applications which only open, read
and write specific files and don't need to enumerate or create directories can disable this option, reducing the
code size by 0.5 kB or more, depending on the filesystem drivers in use.
• CONFIG_VFS_SUPPORT_IO
drivers. This disables all VFS functionality, including the three options mentioned above. When this option is
disabled, console can't be used. Note that the application can still use standard I/O functions with socket file
descriptors when this option is disabled. Compared to the default configuration, disabling this option reduces
code size by about 9.4 kB.
Bootloader Size This document deals with the size of an ESP-IDF app binary only, and not the ESP-IDF
stage bootloader.
For a discussion of ESP-IDF bootloader binary size, see
Espressif Systems
(Alternatively: Leave this option enabled but disable some of the elliptic curves
if both Server & Client are not needed
Modbus, enable or disable
CONFIG_FMB_COMM_MODE_ASCII_EN
—can be disabled if the application doesn't use termios family of
— can be disabled if the application doesn't use select function with
—can be disabled if the application doesn't use directory related functions,
—can be disabled if the application doesn' t use filesystems or file-like peripheral
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CONFIG_FMB_COMM_MODE_TCP_EN,
as applicable for the necessary
Bootloader Size.
CON-
CON-
Second
Release v4.4