Realtime OS to study the issue (and literature)?

Question

Operating Systems

Somehow, by chance, my teacher gently pushed me to study real-time operating systems. Since I am a correspondence student, I will have to study the issue myself, and therefore I am free to choose literature and, in fact, the OS itself - they will ask me for the result, not the process. And the result, something tells me, will be at least a courseworker.
Surely among the numerous Habr specialists there are a couple of professionals in this industry. I ask them to advise me on the literature of the initial and middle level about architecture, and at the same time a subject operating system, for study, open and free, without Hindu code, preferably Unix-like, preferably with hard real-time, and one that knowledge about which may be useful later in professional activities. Thanks in advance.

Answer 1

QNX no options.

Answer 2

en.wikipedia.org/wiki/RTOS

Answer 3

Of the really applicable - QNX and VxWorks.
At the very least, the knowledge gained can be really useful.
A couple of interesting examples for the "seed" - QNX manages drawbridges in St. Petersburg and was used as an OS in the auto-guided system of St. Petersburg metro trains. I am modestly silent about nuclear power plants and pumping stations, as well as heating points =)

Answer 4

Vanilla core with PREEMPT RT patch , approved by Linus Torvalds and completely suitable for all your conditions.

Answer 5

Very popular and certified for many things by VxWorks, which has a bunch of clones, additions and modifications. As close as possible to linux due to the broad adherence to Posix. You can also focus not on a specific OS, but on the standard , the same posix.1b (aka IEEE Std 1003.1b-1993)
Written is true if the ultimate goal is system programming experience in RT.

Answer 6

I can advise this:
art-linux.sourceforge.net/

#include <stdio.h>
#include <stdlib.h>
#include <sys/io.h>
#include <linux/art_task.h>

#define TRUE 1

#define KBD_PORT 0x61
#define SPK_BIT 0x02

main(int argc, char *argv[])
{
    int temp, hz, i;
    hz = atoi(argv[1]);
    ioperm(KBD_PORT, 1, TRUE);
    art_enter(ART_PRIO_MAX, ART_TASK_PERIODIC, 500000 / hz);
    for (i = 0; i < hz * 5; ++i) {
         art_wait();
         temp = inb(KBD_PORT);
         temp = (i & 1) ? temp | SPK_BIT : temp & ~SPK_BIT;
         outb(temp, KBD_PORT);
    }
    art_exit();
}

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/art_task.h>

int main(int argc, char *argv[])
{
    art_prio_t prio;
    if (argc < 3 || (prio = atoi(argv[1])) < ART_PRIO_MIN ||
         prio > ART_PRIO_MAX) {
         fprintf(stderr, "usage: %s prio file arg .../n", argv[0]);
         return -1;
    }
    if (art_enter(prio, ART_TASK_RR, 0) == -1) {
         perror("art_enter");
         return -1;
    }
    if (execvp(argv[2], &argv[2]) == -1) {
         perror("execvp");
         return -1;
    }
    return 0;
}

Answer 7

Thanks to all. After consultations with the teacher, it was decided to stop at QNX, without losing sight of Inferno. Here is a twofold solution.

Answer 8

Portos real-time operating system.
Recently, the range of applications of the BlackBox Component Builder system has been significantly expanded with the Denia cross-programming environment, which is a component extension of BlackBox. Denia allows cross-programming in Component Pascal for the new real-time operating system Portos, which is also fully implemented in Component Pascal. Portos is designed for embedded systems and applications with hard real-time requirements such as robotics and industrial automation.
Source:
delphimaster.net/view/15-1185282701/all
But I can't find either partos or denia anywhere.