changes that reflect reference distribution implementations to PAL layers

Author: rpcme

_docs/concepts/rtos/comparison/index.md

@@ -39,8 +39,8 @@ Table:
 |                                                              |                                          |                                                                                                                          |                                                                                                 |
 | OSEK/VDX                                                     | no                                       | no                                                                                                                       | no                                                                                              |
 | **Maturity**                                                 |                                          |                                                                                                                          |                                                                                                 |
-| First release                                                | 2007                                     | 2014                                                                                                                     | 2016                                                                                            |
-| Last release                                                 | 2019                                     | 2019                                                                                                                     | 2019                                                                                            |
+| First release                                                | 2007                                     | 2003                                                                                                                     | 2016                                                                                            |
+| Last release                                                 | 2019                                     | 2020                                                                                                                     | 2019                                                                                            |
 | Update rate                                                  | about 3 months                           | irregular                                                                                                                | 3 months                                                                                        |
 | Community                                                    | open-source                              | open-source                                                                                                              | Linux Foundation Collaboration Project, (Intel, Linaro (ARM), nordic, NXP, Synopsys)            |
 |                                                              |                                          |                                                                                                                          |                                                                                                 |
@@ -55,25 +55,25 @@ Table:
 | RBS                                                          | no                                       | ?                                                                                                                        | no                                                                                              |
 | Semaphore /Mutex Management                                  | yes (Priority Inheritance)               | yes                                                                                                                      | yes                                                                                             |
 | **IO**                                                       |                                          |                                                                                                                          |                                                                                                 |
-| I2C                                                          | yes                                      | vendor-specific                                                                                                          | yes                                                                                             |
-| SPI                                                          | yes                                      | vendor-specific                                                                                                          | yes                                                                                             |
-| UART                                                         | hw-specific                              | vendor-specific                                                                                                          | yes                                                                                             |
+| I2C                                                          | yes                                      | yes [8]                                                                                                          | yes                                                                                             |
+| SPI                                                          | yes                                      | yes [8]                                                                                                          | yes                                                                                             |
+| UART                                                         | hw-specific                              | yes [8]                                                                                                          | yes                                                                                             |
 | USB                                                          | yes                                      | vendor-specific                                                                                                          | yes                                                                                             |
 | CAN                                                          | yes                                      | vendor-specific                                                                                                          | yes                                                                                             |
 | CAnopen                                                      | no                                       | vendor-specific                                                                                                          | yes                                                                                             |
 | Modbus                                                       | yes                                      | vendor-specific                                                                                                          | ?                                                                                               |
 | **Networking** <sup>7</sup>                                  |                                          |                                                                                                                          |                                                                                                 |
-| BLE-Stack                                                    | unclear                                  | no                                                                                                                       | yes                                                                                             |
+| BLE-Stack                                                    | unclear                                  | yes [8]                                                                                                                       | yes                                                                                             |
 | 6LoWPAN                                                      | yes                                      | no                                                                                                                       | yes                                                                                             |
-| TLS                                                          |                                          | yes                                                                                                                      | yes                                                                                             |
-| Thread                                                       |                                          | ?                                                                                                                        | ?                                                                                               |
-| Ethernet                                                     | yes                                      | no                                                                                                                       | yes                                                                                             |
-| Wifi                                                         | yes                                      | no                                                                                                                       | yes                                                                                             |
+| TLS                                                          |                                          | yes [8]                                                                                                                      | yes                                                                                             |
+| Thread                                                       |                                          | no                                                                                                                        | ?                                                                                               |
+| Ethernet                                                     | yes                                      | yes [8]                                                                                                                       | yes                                                                                             |
+| Wifi                                                         | yes                                      | yes [8]                                                                                                                       | yes                                                                                             |
 | NFC                                                          | unclear                                  | no                                                                                                                       | yes                                                                                             |
 | RFID                                                         | yes                                      | no                                                                                                                       | yes                                                                                             |
 | **Storage & Display** <sup>7</sup>                           |                                          |                                                                                                                          |                                                                                                 |
-| File System                                                  | yes                                      | ?                                                                                                                        | yes                                                                                             |
-| Graphical User Interface                                     |                                          | ?                                                                                                                        | ?                                                                                               |
+| File System                                                  | yes                                      | yes                                                                                                                        | yes                                                                                             |
+| Graphical User Interface                                     |                                          | vendor-specific                                                                                                                        | ?                                                                                               |
 | **Memory Footprint**                                         |                                          |                                                                                                                          |                                                                                                 |
 | RAM                                                          | "small footprint"                        | 236 B scheduler + 64 B / task                                                                                            | "small footprint"                                                                               |
 | ROM                                                          | "small footprint"                        | 5 - 10 kB                                                                                                                | "small footprint"                                                                               |
@@ -96,6 +96,12 @@ Table:
 
 <sup>7</sup> Hardware-support for Networking and Storage often depends on the platform and sometimes packages of hardware-vendors are available, which work for a particular operating system. But it is in general difficult to determine the harware-support of a given RTOS.
 
+<sup>8</sup> FreeRTOS interfaces that are provided through the
+FreeRTOS reference distribution repository at https://github.com/aws/amazon-freertos
+
+<sup>9</sup> FreeRTOS ethernet support is provided through the
+FreeRTOS+TCP stack.
+
 Some Related Work:
 * [Choosing the right RTOS for IoT platform, Milinkovic et al, INFOTEH-JAHORINA Vol. 14, 2015](http://infoteh.rs.ba/zbornik/2015/radovi/RSS-2/RSS-2-2.pdf): comparison of FreeRTOS, ChibiOS/RT, Erika, RIOT
-* [FreeRTOS Architecture](https://www.freertos.org/)
+* [FreeRTOS Architecture](https://www.freertos.org/)