Zephyr

Overview

This NN page a holding point for notes and links to external references regarding Zephyr RTOS, and Zephyr RTOS Project. Some key features of Zephyr RTOS include its designers' incorporation of Device Tree Source and Kconfig frameworks in this real time operating system.

As of 2023 April this page under reorganization, pulling multiple local pages into this page and removing older and defunct content - TMH

For device tree and Kconfig see also:

• https://www.kernel.org/doc/html/latest/kbuild/kconfig-language.html

^ Zephyr RTOS Logger and Backend Features

• https://docs.zephyrproject.org/2.6.0/reference/logging/index.html#logger-backend-interface
• https://docs.zephyrproject.org/2.6.0/reference/logging/index.html#default-frontend

Zephyr's thread_analyzer when not configured to dump reports to printk() instead sends thread data to LOG_INF(). Excerpt from Zephyr file `./zephyr/subsys/debug/thread_analyzer.c`:

 11 #include <kernel.h>
 12 #include <debug/thread_analyzer.h>
 13 #include <debug/stack.h>
 14 #include <kernel.h>
 15 #include <logging/log.h>
 16 #include <stdio.h>
 17 
 18 LOG_MODULE_REGISTER(thread_analyzer, CONFIG_THREAD_ANALYZER_LOG_LEVEL);
 19 
 20 #if IS_ENABLED(CONFIG_THREAD_ANALYZER_USE_PRINTK)
 21 #define THREAD_ANALYZER_PRINT(...) printk(__VA_ARGS__)
 22 #define THREAD_ANALYZER_FMT(str)   str "\n"
 23 #define THREAD_ANALYZER_VSTR(str)  (str)
 24 #else
 25 #define THREAD_ANALYZER_PRINT(...) LOG_INF(__VA_ARGS__)
 26 #define THREAD_ANALYZER_FMT(str)   str
 27 #define THREAD_ANALYZER_VSTR(str)  log_strdup(str)
 28 #endif

Zephyr macro `LOG_INF` is in turn defined:

ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/zephyr$ grep -nr LOG_INF ./* | grep define

./include/logging/log.h:61:#define LOG_INF(...)   Z_LOG(LOG_LEVEL_INF, __VA_ARGS__)

Define of Z_LOG:

ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/zephyr$ grep -nr 'Z_LOG[^_]' ./*

./include/logging/log_core.h:295:#define Z_LOG2(_level, _source, _dsource, ...) do { \
./include/logging/log_core.h:329:#define Z_LOG(_level, ...) \

$ grep -nr 'Z_LOG[^_]' ./*

$ vi ./include/logging/log_core.h

329 #define Z_LOG(_level, ...) \
330         Z_LOG2(_level, __log_current_const_data, __log_current_dynamic_data, __VA_ARGS__)

A Zephyr RTOS sample to check out:

`ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/zephyr/samples/subsys/logging/logger$`

- 2022-10-05 -

Zephyr v2.6.0 source file `log_core.h` may also define `log_strdup()`:

./subsys/logging/log_core.c:1017:char *z_log_strdup(const char *str)

But it looks like the routine is statically in-lined in Zephyr header file `log.h`:

./include/logging/log.h:290:static inline char *log_strdup(const char *str)

^ To Create And To Name Zephyr Threads

• https://docs.zephyrproject.org/latest/reference/kernel/threads/index.html?highlight=k_thread_define#c.K_THREAD_DEFINE

• https://docs.zephyrproject.org/latest/reference/kernel/threads/index.html?highlight=k_thread_create#c.k_thread_name_set

^ Zephyr thread_analyzer_cb And Related

Zephyr 2.6.0's thread_analyzer_cb() routine gathers and populates a structure with all pertinent, reported run-time thread statistics. This is however a static routine so we cannot call it directly. Nor does it return the summary thread resource use data to its direct calling routine. There is yet hope, and to understand a path forward here excerpted is the definition of this important thread reporting routine from file `./zephyr/subsys/debug/thread_analyzer.c`:

 59 static void thread_analyze_cb(const struct k_thread *cthread, void *user_data)
 60 {
 61         struct k_thread *thread = (struct k_thread *)cthread;
 62 #ifdef CONFIG_THREAD_RUNTIME_STATS
 63         k_thread_runtime_stats_t rt_stats_all;
 64         k_thread_runtime_stats_t rt_stats_thread;
 65         int ret;
 66 #endif
 67         size_t size = thread->stack_info.size;
 68         thread_analyzer_cb cb = user_data;
 69         struct thread_analyzer_info info;
 70         char hexname[PTR_STR_MAXLEN + 1];
 71         const char *name;
 72         size_t unused;
 73         int err;
 74 
 75 
 76 
 77         name = k_thread_name_get((k_tid_t)thread);
 78         if (!name || name[0] == '\0') {
 79                 name = hexname;
 80                 snprintk(hexname, sizeof(hexname), "%p", (void *)thread);
 81         }
 82 
 83         err = k_thread_stack_space_get(thread, &unused);
 84         if (err) {
 85                 THREAD_ANALYZER_PRINT(
 86                         THREAD_ANALYZER_FMT(
 87                                 " %-20s: unable to get stack space (%d)"),
 88                         name, err);

 88                         name, err);
 89 
 90                 unused = 0;
 91         }
 92 
 93         info.name = name;
 94         info.stack_size = size;
 95         info.stack_used = size - unused;
 96 
 97 #ifdef CONFIG_THREAD_RUNTIME_STATS
 98         ret = 0;
 99 
100         if (k_thread_runtime_stats_get(thread, &rt_stats_thread) != 0) {
101                 ret++;
102         }
103 
104         if (k_thread_runtime_stats_all_get(&rt_stats_all) != 0) {
105                 ret++;
106         }
107         if (ret == 0) {
108                 info.utilization = (rt_stats_thread.execution_cycles * 100U) /
109                         rt_stats_all.execution_cycles;
110         }
111 #endif
112         cb(&info);
113 }

The routine which calls this is:

115 void thread_analyzer_run(thread_analyzer_cb cb)
116 {
117         if (IS_ENABLED(CONFIG_THREAD_ANALYZER_RUN_UNLOCKED)) {
118                 k_thread_foreach_unlocked(thread_analyze_cb, cb);
119         } else {
120                 k_thread_foreach(thread_analyze_cb, cb);
121         }
122 }

We should be able to directly call thread_analyzer_run(thread_analyzer_cb cb). If yes, and if we can learn how &info is defined, we should be able to redirect thread_analyzer reports to an arbitrary UART . . .

^ struct thread_analyzer_info

ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/zephyr$ grep -nr 'struct thread_analyzer_info' ./*
./include/debug/thread_analyzer.h:23:struct thread_analyzer_info {
./include/debug/thread_analyzer.h:44:typedef void (*thread_analyzer_cb)(struct thread_analyzer_info *info);

Structure definition for &info passed to thread_analyzer_cb() function above:

/** @defgroup thread_analyzer Thread analyzer
 *  @brief Module for analyzing threads
 *
 *  This module implements functions and the configuration that simplifies
 *  thread analysis.
 *  @{
 */

struct thread_analyzer_info {
        /** The name of the thread or stringified address of the thread handle
         * if name is not set.
         */
        const char *name;
        /** The total size of the stack*/
        size_t stack_size;
        /** Stack size in used */
        size_t stack_used;

#ifdef CONFIG_THREAD_RUNTIME_STATS
        unsigned int utilization;
#endif
};

Zephyr Memory Management

• https://link.springer.com/chapter/10.1007/978-3-030-25543-5_29

^ Zephyr Kernel Timing

Following link at Zephyr Project documentation pages has valuable info on various Zephyr timing and work queueing facilities:

• https://docs.zephyrproject.org/2.6.0/reference/kernel/timing/clocks.html?highlight=k_uptime
Similar documentation but describes sources of timing inaccuracies in running Zephyr RTOS relative to civil, real world time:
• https://docs.zephyrproject.org/2.6.0/reference/misc/timeutil.html?highlight=k_uptime_get
Must #include <kernel.h> . . .
• https://docs.zephyrproject.org/apidoc/latest/group__clock__apis.html#ga208687de625e0036558343b4e66143d3

Related:

• https://docs.zephyrproject.org/2.6.0/reference/kernel/timing/clocks.html?highlight=k_uptime#uptime

Important to follow up on this bug report relating to above mentioned Zephyr timing features:

• https://github.com/zephyrproject-rtos/zephyr/issues/16238

^ Zephyr Application Code Relocation

• https://docs.zephyrproject.org/3.1.0/kernel/code-relocation.html

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