Are there any opensource/free Unix like RTOS that can run a virtual machine like QNX Neutrino RTOS (http://www.qnx.com/products/evaluation/eval-target.html) ?

I've a question about real-time systems, in particular in LynxOS (LynxOS-178). I would need information on the compatibility and presence of eBPF in these systems. Can anyone help me? I haven't found any documentation online, but I would like to have this information to be able to evaluate which product is best to use to achieve my purpose.

I am using a resource manager to read the data from the communication channel and send it to the application. I have doubt, is the QNX resource manager half duplex or full duplex? Can simultaneous read/write work with QNX resource manager?

I'm trying to determine if a particular given C language source code run on [Unison OS](https://rowebots.com/unison-rtos/) that I have could conceivably lead to a crash, and through what vectors. There are sections of the code that will on occasion attempt to dereference null pointers, access, but not write to, array indices out of bounds, and use possibly uninitialized variables. The behavior is undefined and thus unpredictable in C, but according to other discussions I've read, the operating system and/or CPU will have a default behavior in these kinds of situations. I don't own the code in question and I'm not trying to fix it. I just want to understand on a high level if there's a reasonable possibility of any of these (and which) leading to the program crashing.

IEEE Std 1003.13-2003 defines a set of POSIX profiles for real-time systems. PSE51 is one of these profiles. I'm studying about PSE51 and I think it would be very helpful if I had access to an implementation of an RTOS compliant with this profile. Looking at some code always makes things clearer than reading requirements and specifications. I already did a research but just found proprietary implementations. Is there an open source implementation of an RTOS compliant with PSE51 or any other of the real-time profiles?

Recently in an interview I was asked about the Scheduling algorithm used by Linux Operating system. What is the algorithm used any why? Also, what algorithm is used in in real-time operating systems and why?

I am following [this]. To run make -j$(nproc) make modules -j$(nproc) I know that make is running [jobs] **Are the jobs supposed to run for hours?** (I got impatient and interrupted.) make -j$(nproc)

I am trying to install RTAI 5.0.1 on Ubuntu 18.04 LTS in Linux Kernel 4.1.18. I was following [this] tutorial. But unfortunately I am stuck in this part make -j getconf _NPROCESSORS_ONLN deb-pkg LOCALVERSION=-rtai The error is: make: *** No rule to make target 'deb-pkg'. Stop. What should be the target?

If I wanted to learn deeply and build a embedded Linux Operating systems would i benefit from knowing about RTOS or can I straight away go for embedded Linux.

How to set thread priority in RTLinux? Also, what is the range of priority levels; which is highest priority and which is lowest?

I have to set up RTLinux and run a real-time ST language interpreter. The official RTLinux has been abandoned and its official download site does not work. I decided to use community RT_PREEMPT patch. How to configure it to achieve the most accurate timing? I'm currently using Debian Wheezy on NP-R540-JS01PL notebook. I downloaded 3.18.9 kernel and 3.18.9-rt5 patch. I copied /boot/.config to source directory as mentioned on Wiki and changed preemt mode to fully preemtive kernel. Which other options do I need to change? Will I get accurate results when I just replace old Debian kernel with the patched kernel? Notice that I'm running full Debian Wheezy with XFCE desktop environment. Another option is to create a separate Linux distro only with patched kernel and basic command-line tools. How about drivers and kernel modules? My CPU has virtualization support. If I set up RTLinux on VirtualBox on Win7 or Debian Squeezy, will virtualized RTLinux still behave realtime? Note that ST language interpreter will communicate with another application or service that will load ST code into the machine, read/write memory, blink LEDs, set time, parameters, etc.

How could I compile the [FreeRTOS Source Code](http://www.freertos.org/a00104.html?1) and run it (possibly on qemu) on Ubuntu 11.04?

When developing a solution that requires a real-time operating system, what advantages would an operating system such an QNX or VxWorks have over Linux? Or to put it another way, since these operating system are designed specifically for real-time, embedded use - as opposed to Linux which is a more general system that can be tailored to real-time use - when would you *need* to use one of these operating systems instead of Linux?