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feat(newlib): add picolibc support

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Alexey Lapshin
2024-09-26 13:13:20 +07:00
parent 22a38779fb
commit 888b5f7e8d
171 changed files with 8438 additions and 1016 deletions
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9
docs/en/api-guides/c.rst
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@@ -3,7 +3,14 @@ C Support
:link_to_translation:`zh_CN:[中文]`
ESP-IDF is primarily written in C and provides C APIs. ESP-IDF uses `Newlib <https://sourceware.org/newlib/>`_ as its C Standard Library implementation (the Newlib version is specified in :component_file:`newlib/sbom.yml`). In general, all C features that are supported by the compiler (currently GCC) can be used in ESP-IDF, unless specified in :ref:`unsupported_c_features` below.
ESP-IDF is primarily written in C and provides C APIs. ESP-IDF can use one of the following C Standard Library implementations:
- `Newlib <https://sourceware.org/newlib/>`_ (default)
- `Picolibc <https://keithp.com/picolibc/>`_ (enabled with :ref:`CONFIG_LIBC_PICOLIBC<CONFIG_LIBC_PICOLIBC>` Kconfig option)
The Newlib version is specified in :component_file:`newlib/sbom.yml`.
In general, all C features supported by the compiler (currently GCC) can be used in ESP-IDF, unless otherwise noted in :ref:`unsupported_c_features` below.
.. _c_version:

2
docs/en/api-guides/lwip.rst
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@@ -173,7 +173,7 @@ Example:
Socket Error Reason Code
++++++++++++++++++++++++
Below is a list of common error codes. For a more detailed list of standard POSIX/C error codes, please see `newlib errno.h <https://github.com/espressif/newlib-esp32/blob/master/newlib/libc/include/sys/errno.h>`_ and the platform-specific extensions :component_file:`newlib/platform_include/errno.h`.
Below is a list of common error codes. For a more detailed list of standard POSIX/C error codes, please see `newlib errno.h <https://github.com/espressif/newlib-esp32/blob/master/newlib/libc/include/sys/errno.h>`_ and the platform-specific extensions :component_file:`newlib/platform_include/sys/errno.h`.
.. list-table::
:header-rows: 1

1
docs/en/api-guides/performance/ram-usage.rst
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@@ -96,6 +96,7 @@ Reducing Stack Sizes
- Avoid stack heavy functions. String formatting functions (like ``printf()``) are particularly heavy users of the stack, so any task which does not ever call these can usually have its stack size reduced.
- Using experimental :ref:`picolibc-instead-of-newlib` reduces the stack usage of ``printf()`` calls significantly.
- Enabling :ref:`newlib-nano-formatting` reduces the stack usage of any task that calls ``printf()`` or other C string formatting functions.
- Avoid allocating large variables on the stack. In C, any large structures or arrays allocated as an automatic variable (i.e., default scope of a C declaration) uses space on the stack. To minimize the sizes of these, allocate them statically and/or see if you can save memory by dynamically allocating them from the heap only when they are needed.

17
docs/en/api-guides/performance/size.rst
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@@ -151,6 +151,17 @@ lwIP IPv4
Before disabling IPv4 support, please note that IPv6 only network environments are not ubiquitous and must be supported in the local network, e.g., by your internet service provider or using constrained local network settings.
.. _picolibc-instead-of-newlib:
Picolibc instead of Newlib
@@@@@@@@@@@@@@@@@@@@@@@@@@
By default, ESP-IDF uses the Newlib C library, and it also has experimental support for the Picolibc C library.
Picolibc C library provides smaller ``printf``-family functions and can reduce the binary size by up to 30 KB, depending on your application.
To switch to linking against the Picolibc C library, please enable the configuration options :ref:`CONFIG_IDF_EXPERIMENTAL_FEATURES` and :ref:`CONFIG_LIBC_PICOLIBC<CONFIG_LIBC_PICOLIBC>`.
.. _newlib-nano-formatting:
Newlib Nano Formatting
@@ -160,13 +171,13 @@ By default, ESP-IDF uses Newlib "full" formatting for I/O functions (``printf()`
.. only:: CONFIG_ESP_ROM_HAS_NEWLIB_NANO_FORMAT
Enabling the config option :ref:`CONFIG_NEWLIB_NANO_FORMAT` will switch Newlib to the "Nano" formatting mode. This is smaller in code size, and a large part of the implementation is compiled into the {IDF_TARGET_NAME} ROM, so it does not need to be included in the binary at all.
Enabling the config option :ref:`CONFIG_LIBC_NEWLIB_NANO_FORMAT` will switch Newlib to the "Nano" formatting mode. This is smaller in code size, and a large part of the implementation is compiled into the {IDF_TARGET_NAME} ROM, so it does not need to be included in the binary at all.
The exact difference in binary size depends on which features the firmware uses, but 25 KB ~ 50 KB is typical.
.. only:: CONFIG_ESP_ROM_HAS_NEWLIB_NORMAL_FORMAT
Disabling the config option :ref:`CONFIG_NEWLIB_NANO_FORMAT` will switch Newlib to the "full" formatting mode. This will reduce the binary size, as {IDF_TARGET_NAME} has the full formatting version of the functions in ROM, so it does not need to be included in the binary at all.
Disabling the config option :ref:`CONFIG_LIBC_NEWLIB_NANO_FORMAT` will switch Newlib to the "full" formatting mode. This will reduce the binary size, as {IDF_TARGET_NAME} has the full formatting version of the functions in ROM, so it does not need to be included in the binary at all.
Enabling "Nano" formatting reduces the stack usage of each function that calls ``printf()`` or another string formatting function, see :ref:`optimize-stack-sizes`.
@@ -177,7 +188,7 @@ Enabling "Nano" formatting reduces the stack usage of each function that calls `
.. note::
:ref:`CONFIG_NEWLIB_NANO_FORMAT` is enabled by default on {IDF_TARGET_NAME}.
:ref:`CONFIG_LIBC_NEWLIB_NANO_FORMAT` is enabled by default on {IDF_TARGET_NAME}.
.. _Newlib README file: https://sourceware.org/newlib/README

4
docs/en/api-guides/stdio.rst
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@@ -101,8 +101,8 @@ VFS drivers provide an optional newline conversion feature for input and output.
Applications can configure this behavior globally using the following Kconfig options:
- :ref:`CONFIG_NEWLIB_STDOUT_LINE_ENDING_CRLF<CONFIG_NEWLIB_STDOUT_LINE_ENDING_CRLF>`, :ref:`CONFIG_NEWLIB_STDOUT_LINE_ENDING_CR<CONFIG_NEWLIB_STDOUT_LINE_ENDING_CR>`, :ref:`CONFIG_NEWLIB_STDOUT_LINE_ENDING_LF<CONFIG_NEWLIB_STDOUT_LINE_ENDING_LF>` - for output
- :ref:`CONFIG_NEWLIB_STDIN_LINE_ENDING_CRLF<CONFIG_NEWLIB_STDIN_LINE_ENDING_CRLF>`, :ref:`CONFIG_NEWLIB_STDIN_LINE_ENDING_CR<CONFIG_NEWLIB_STDIN_LINE_ENDING_CR>`, :ref:`CONFIG_NEWLIB_STDIN_LINE_ENDING_LF<CONFIG_NEWLIB_STDIN_LINE_ENDING_LF>` - for input
- :ref:`CONFIG_LIBC_STDOUT_LINE_ENDING_CRLF<CONFIG_LIBC_STDOUT_LINE_ENDING_CRLF>`, :ref:`CONFIG_LIBC_STDOUT_LINE_ENDING_CR<CONFIG_LIBC_STDOUT_LINE_ENDING_CR>`, :ref:`CONFIG_LIBC_STDOUT_LINE_ENDING_LF<CONFIG_LIBC_STDOUT_LINE_ENDING_LF>` - for output
- :ref:`CONFIG_LIBC_STDIN_LINE_ENDING_CRLF<CONFIG_LIBC_STDIN_LINE_ENDING_CRLF>`, :ref:`CONFIG_LIBC_STDIN_LINE_ENDING_CR<CONFIG_LIBC_STDIN_LINE_ENDING_CR>`, :ref:`CONFIG_LIBC_STDIN_LINE_ENDING_LF<CONFIG_LIBC_STDIN_LINE_ENDING_LF>` - for input
It is also possible to configure line ending conversion for the specific VFS driver: