feat(freertos): Added FreeRTOS POSIX/Linux Simulator

* Added port layer from the FreeRTOS POSIX port, added
  additional port code for ESP-IDF.
* Created another hello world example using that POSIX
  port in tools/test_apps.
* Removed old linux app

examples/build_system/.build-test-rules.yml

@@ -6,11 +6,6 @@ examples/build_system/cmake/import_lib:
       temporary: true
       reason: lack of runners
 
-examples/build_system/cmake/linux_host_app:
-  enable:
-    - if: IDF_TARGET == "linux"
-      reason: only test on linux
-
 examples/build_system/cmake/plugins:
   disable_test:
     - if: IDF_TARGET not in ["esp32", "esp32c3"]

examples/build_system/cmake/linux_host_app/CMakeLists.txt

@@ -1,10 +0,0 @@
-cmake_minimum_required(VERSION 3.16)
-
-include($ENV{IDF_PATH}/tools/cmake/project.cmake)
-set(COMPONENTS main)
-
-# Freertos is included via common components, however, currently only the mock component is compatible with linux
-# target.
-list(APPEND EXTRA_COMPONENT_DIRS "$ENV{IDF_PATH}/tools/mocks/freertos/")
-
-project(linux_host_app)

examples/build_system/cmake/linux_host_app/README.md

@@ -1,38 +0,0 @@
-| Supported Targets | Linux |
-| ----------------- | ----- |
-
-This hello-world example builds a simple hello-world application for Linux.
-The compiler used is the Linux-gcc.
-
-There are two major differences to an IDF application built for an ESP chip compared to an application build for Linux:
-
-1. The entry-point on Linux is `int main(int argc, char **argv)`, instead of `void app_main(void)` on an ESP chip.
-   In this example for Linux, the `void app_main(void)` function is still included to make the connection to the IDF entry point clearer.
-   However, it is simply called by `int main(int argc, char **argv)`.
-   Refer to the source file [linux_host_app.cpp](main/linux_host_app.cpp) to see how it is used.
-
-2. The project-level [CMakeLists.txt](CMakeLists.txt) for Linux is different from that of a normal IDF application for an ESP chip.
-   On Linux, there is an additional line `set(COMPONENTS main)`, which clears the common requirements (default dependencies usually included in all IDF applications).
-   This is currently necessary as the Linux-host feature is still under development.
-   Otherwise, a lot of hardware-dependent code would be pulled in.
-
-# Requirements
-Currently, Ruby is required for the mock override of FreeRTOS.
-
-# Build
-Source the IDF environment as usual, then set the Linux target:
-```bash
-idf.py --preview set-target linux
-```
-sdkconfig.defaults sets the Linux target by default, so this not strictly necessary.
-
-Once this is done, build the application:
-```bash
-idf.py build
-```
-Since this application runs on host, the flashing step is unnecessary.
-
-# Run
-```bash
-`build/linux_host_app.elf`
-```

examples/build_system/cmake/linux_host_app/main/CMakeLists.txt

@@ -1 +0,0 @@
-idf_component_register(SRCS "linux_host_app.cpp")

examples/build_system/cmake/linux_host_app/main/linux_host_app.cpp

@@ -1,30 +0,0 @@
-/* Hello World Example
-
-   This example code is in the Public Domain (or CC0 licensed, at your option.)
-
-   Unless required by applicable law or agreed to in writing, this
-   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-   CONDITIONS OF ANY KIND, either express or implied.
-*/
-
-#include "stdio.h"
-#include <unistd.h>
-
-void app_main() {
-    while(1) {
-        printf("Hello, Host!\n");
-
-        for (int i = 10; i >= 0; i--) {
-            printf("Restarting in %d seconds...\n", i);
-            sleep(1);
-        }
-    }
-}
-
-int main(int argc, char **argv)
-{
-    setbuf(stdout, NULL);
-    app_main();
-
-    return 0;
-}

examples/build_system/cmake/linux_host_app/sdkconfig.defaults

@@ -1,3 +0,0 @@
-CONFIG_UNITY_ENABLE_IDF_TEST_RUNNER=n
-CONFIG_IDF_TARGET="linux"
-CONFIG_COMPILER_CXX_EXCEPTIONS=y