I want to make a sort of operating system, but with some very specific features.
The only thing i need it to do is show a video, place some text over it, accept user input and some basic file manipulation.
Something that looks like an OS'es loading screen would do.
i am, however, a complete noob to this part of programming and i have no idea where to look. Don't worry i do not need a complete explaination for every single step, but it would be nice to know in what direction i should go search.
Anyone got an idea where to start searching?
Thanks in advance ;)
Although you narrowed down your specification it's still complicated enough. Playing video involves file I/O, a file system, storage device access, buffering mechanism, memory allocation, memory management primitives, GPU access. Accepting user input requires keyboard and mouse handling which requires a working USB layer. Not to mention that you needed to make the video decoding library work with your own system, unless you want to implement that from scratch too. That might require you to have an ABI or a POSIX emulation layer. You might need to port at least one or two graphics libraries like SDL.
That's why "OS loading screen"s don't play videos :)
You might get away with using BIOS only for accessing all devices. But BIOS and VBE are usually slow and may not work well with your video playing scenario. BIOS is slowly getting pushed out of PC ecosystem in favor of UEFI too.
If you don't need a custom OS, you can trim a Linux kernel down to the parts you need to have. Even that's not a trivial thing to do though.
Related
I am a mathematician and not a programmer, I have a notion on the basics of programming and am a quite advanced power-user both in linux and windows.
I know some C and some python but nothing much.
I would like to make an overlay so that when I start a game it can get info about amd and nvidia GPUs like frame time and FPS because I am quite certain the current system benchmarks use to compare two GPUs is flawed because small instances and scenes that bump up the FPS momentarily (but are totally irrelevant in terms of user experience) result in a higher average FPS number and mislead the market either unintentionally or intentionally (for example, I cant remember the name of the game probably COD there was a highly tessellated entity on the map that wasnt even visible to the player which lead AMD GPUs to seemingly under perform when roaming though that area leading to lower average FPS count)
I have an idea on how to calculate GPU performance in theory but I dont know how to harvest the data from the GPU, Could you refer me to api manuals or references to help me making such an overlay possible?
I would like to study as little as possible (by that I mean I would like to learn what I absolutely have to learn in order to get the job done I dont intent to become a coder).
I thank you in advance.
It is generally what the Vulkan Layer system is for, which allows to intercept API commands and inject your own. But it is nontrivial to code it yourself. Here are some pre-existing open-source options for you:
To get to timing info and draw your custom overlay you can use (and modify) a tool like OCAT. It supports Direct3D 11, Direct3D 12, and Vulkan apps.
To just get the timing (and other interesting info) as CSV you can use a command-line tool like PresentMon. Should work in D3D, and I have been using it with Vulkan apps too and it seems to accept them.
Some background:
I am a Computer Engineering major attending school right now, and I just completed a project that created a microprocessor with a super simple instruction set that ran on an FPGA. I chose to implement a simple file storage scheme, a VGA text only display output, and a PS/2 keyboard input. I wrote two main programs, a firmware that was in ROM in the processor and a kernel that provided a bunch of library type functions, and was capable of loading and executing files from the filesystem. This project was challenging and overall a lot of fun.
My Question:
I want to do some super low level programming on a modern computer, but I can't seem to find any resources or documentation that help me get started. To be clear, I want to find the proper documentation that would help me to write a program in C, x86, or x86-64 assembly that I could compile, and format into some form of bootable data. I know this is a daunting task, and typically not something a hobbyist would take on, but I know that it's possible (Terry Davis's TempleOS).
Are there any websites or books that I can read that will contain the specifics needed to make something like this?
Look out, you might just catch the bug. OS Development, though having a very small demographic, is still quite a thriving hobby. Once you start, you may not ever give it up.
Since your subject line states 64-bit and you use the term modern hardware, be advised that modern hardware no longer has the older style BIOS, where the developer wrote the boot process which included the video out, file system in, and other standard routines. Modern hardware now uses an EFI firmware which does all of the booting for you, including the reading from the file system(s). For modern hardware, OS development really starts with the OS Loader, the part that loads the OS, and this is done in a high level language such as C/C++. Very little if any assembly at all, in fact that is its point/purpose.
Don't get too discouraged, currently a lot of computers still allow the old style boot. However, the old style boot starts in 16-bit mode, moves to 32-bit mode, then if desired, moves to long mode (64-bit). There also are emulators that you can use so you don't have to have a separate system, just to test your development. I prefer Bochs myself, but I am a little bias since I wrote some of the code for it, namely most of the (original) USB emulation.
If you wish to dip your toes into this hobby, there are numerous places to start. I personally wrote a few books on the subject. They show you how to start from when the time the POST gives up control to your boot code, up to the point of a minimal Round Robin style task/thread switching OS, with all the necessary hardware and software basics to do so. There is a forum to OS Development, along with its wiki.
Again, a project like this is not for the faint at heart, though it is an enjoyable hobby most have found to be a very good learning experience.
Although I have implemented many projects in C, I am completely new to operating systems. I tried real time linux on Discovery board (STM32) and got the correct results for blinking LED but I didn't really understand the whole process since I just followed the steps and could not find whole description for each step on the internet.
I want to implement scheduling on real time linux. What is the best way to start? Any sites, books, tutorials available?
Complete RTLinux process description will be appreciated.
Thanks in adv.
The transition from "bare metal" to OS based programming is something that I experienced in reverse. I started out a complete software guy, totally into the OS side of things and over time I have moved to the opposite of that (even designing circuits in VHDL!). My advice would be to start simple. Linux is pretty complex, and everywhere you look there are many layers of things all working together to deliver the final product. If you are dead set on a real time linux extension, I'd be happy to suggest https://xenomai.org/ which is a real time extension for linux.
However, to more specifically address your question about implementing scheduling in Linux, you can, but it will be a large amount of work and can be very complicated. The OS uses a completely fair scheduling process ( http://en.wikipedia.org/wiki/Completely_Fair_Scheduler ) and whenever you spin up a thread, it simply gets added to the list to run. This can differ slightly if you implement your code in kernel space as a driver, rely on hardware interrupts, etc., but in general, this is how Linux works. Real time generally means that it has the ability to assign threads one of several different priorities and utilize thread preemption fully at any given time which are concepts that aren't really a part of vanilla Linux. It has some notion of this, but it has limitations that can cause problems when you are looking for real time behavior from Linux.
What may be helpful to you is an RTOS. If you are looking for a full on Real Time Operating System, check out FreeRTOS http://www.freertos.org/ . It has a large community and supports a lot of different devices out of the box with a large amount of example code. They even support your specific board with an example package, so you can give it a shot with nothing to lose! http://www.freertos.org/FreeRTOS-for-Cortex-M3-STM32-STM32F100-Discovery.html . It gives you access to many OS ish constructs like network APIs, memory management, and threading without the overhead and latency of a huge OS. With an RTOS, you create tasks and assign them priorities so you become the scheduler and are no longer at the mercy of the OS. You run the OS, not the OS runs you (if that makes sense). Plus, the constructs offered within an RTOS will feel much like bare metal code and thus will be much easier to follow, understand, and fully learn. It is a more simple world to learn the base building blocks of a full blown OS such as Linux or Windows. If this option sounds good, I would suggest looking through the supported devices on FreeRTOS website and picking one you would like to experiment with and then go for it. I would highly recommend this as a way to learn about scheduling and OS constructs in general as it is as simple as you can get and open source. Once you have the basics of an RTOS down, buying a book about Linux specifically wouldn't be a bad idea. Although there are many free resources on the web related to learning about Linux, they are commonly contradictory, and can be misleading. Pile on learning Linux specific knowledge along with OS in general, and it can feel overwhelming. Starting simpler will help keep you from getting burnt out and minimize the amount of time you spend feeling lost. Linux is definitely a learning process, but like with any learning process, start simple, keep your ultimate goal in mind, make a plan, and take small, manageable steps along that plan until you look up and find yourself exactly where you want to be. Then go tackle the next mountain!
The real-time Linux landscape is quite confusing. 99.99% of the information out there is just plain obsolete.
First, there are lots of "microkernels" that run Linux as one task. (Such as the defunct RTLinux). The problem is that you must write your real-time task to a different API, and can't depend on anything in Linux, because Linux will be frozen in the background while your task runs. So unless your task is dead-simple ("stop the motors when I press this button"), this approach will cause more pain than gain.
Next, there is the realtime Linux patch set. This hasn't been doing so well. because of the next item:
Lastly, the current Linux kernel has gotten rid of the problems that caused people to need realtime in the past. You can even turn off Linux on one of your processors to have full control of the CPU. See also this paper.
To answer your question: I see two different paths you could take:
1) Start with a normal 3.xx Linux kernel and explore the various APIs and realtime techniques (i.e. realtime priorities, memory pinning, etc.) This can get you "close enough" for 99% of what people want "realtime" for. If it's good enough for high frequency trading, it's probably good enough for you.
2) If you have a hard realtime requirement and you are worried that Linux won't cut it, then (as Nick mentioned above), just go buy a processor and write your realtime code with no OS. By splitting up your "realtime" and "non-realtime" code onto different CPUs, you will make the whole system simpler and much more robust.
If you want to learn real-time operating systems then I suggest that you get an FPGA, for example the Altera DE2, and experiment with your own operating system and ucos. You can read a good text about embedded RTOS here.
You could also get a Linux Raspberry and write your own operating system for that.
I alongwith some friends of mine was having this idea of creating a very basic media player,Say it only plays mp3s(very limited GUI showing the controls of the player).The Tricky part is we wish to do it without any OS.i.e It will be loaded directly from the boot loader and we will read the file off from a pen drive.Is this a feasible project idea.Its a hobby project so there is no time limit as of now. Can someone guide me as to how to proceed?
If you want to do this from scratch, all I can say is good luck. Yu'd have to write file system drivers, sound drivers, display drivers, keyboard drivers, mouse drivers, USB drivers, etc. it would be a massive amount of work.
Instead, if you still want to write things like the mp3 codec yourself, you can, but do it on top of an existing Os. You could go with DOS if you wanted, and have at least something built in to work off of. If I were doing this, I'd be going with embedded Linux + x11. But it's your choice.
i have never done embedded (i dont know if thats what you call this) programming and know nothing about it. my question:
is it possible to have two devices sharing a wireless connection (no internet, just between themselves, perhaps bluetooth, but i dont know what ever is best) ?
is it possible to have one editing a file and the other person editing the same file and they can see changes in real time? sort of like google docs?
does this exist already?
what can i do to get started regarding this kind of programming?
to clarify:
i want two people with iphones or any other hand held device, to be able to edit a text file at the same time and see each other's changes in real-time. how do i do this?
There are a bunch of slightly strange assumptions hidden in your questions. I'll try to unpick them as best as I can.
You've used "embedded" programming in a strange way. Usually this would suggest some kind of low-power devices used in settings without direct user interaction in some sense (e.g. factory controllers, refrigerator controllers, sensor nodes), performing a very specific task, but you've gone on to talk bout people editing files. What exactly would be the user interface here? What would make this embedded programming? I think you need to describe an application before any advice can be offered.
If you actually mean embedded devices, then whether they can connect wirelessly to one another is going to depend on the nature of the device. Similarly, the protocol/technologies involved will depend on the device. Embedded programming tends to be very much device-specific. There certainly exist wireless sensor nodes, for example, that incorporate small radio transceivers for serial comms.
Google docs already exists. Without a clearer problem description it's difficult to say whether what you want exists already or not.
I think you should really figure out exactly what kind of programming it is that you want to do before we can offer points as to how to best get started with it. Maybe look up a definition of "embedded programming" and see how this relates to your goals such that you can reformulate your questions a little more clearly.
I'm not sure how "real time" would fit into this scenario either. This term is used and abused in many ways. Things are only ever real-time with respect to some constraint, usually defined in terms of the application.
(Note: This might have been more appropriate as a comment, but I felt there was too much to respond to in order to sum up within character limits, and I hope correcting some of the confusion constitutes something of an answer, given the limitations of the question).
Two devices can share a connection like this. It's done all the time. There are many many protocols for this. Weather or not it is wired or wireless or uses the Internet doesn't really matter for 90% of this.
This is sort of doable, but not really. You really have a race condition when two people are editing at the same time. This is generally avoidable by locking out small parts of the document at from all but one editor at a time (like only one person being able to edit one cell of a spreadsheet at a time), but this has problems too (like of the one active editor is taking way too long -- this is a problem seen in many source version control systems too).
1 already exists in many many forms. 2 sort of exists in many forms, but the problems I mentioned are impossible to completely overcome.
The way you asked this question leads me to believe that you are very far from being able to do this. In addition, you didn't tell us anything about what you do know how to do. Can you write a simple text editor for an iPhone (or anything else)? Simple text editors from scratch that aren't crappy aren't easy to write.
What you need to do, if you really want to do this, is to come up with a protocol for the two (or more) devices to talk to each other in. To do this it is probably best if you figure out what type of communication is available between the devices and which of those you will use and what features it does not provide that you will need on top.
You could try to send patches of the file (or something similar) between the two devices as edits are made, but then you'll have to decide what to do in the event of a collision (edits near the same place).
Alternately you could have the two devices exchange permission to make edits (like in token ring networks).
You still have a problem if the two devices lose communication with each other during the editing of the file, though. With the token ring type setup you stand the possibility of losing the token and neither being able to automatically recover easily. Whatever you do you end up with the problem of the two ending up with different ideas of the file's contents.
"iphones or any other hand held device" - the technology stack to do that doesn't exist today. You have to co-ordinate between multiple languages and systems. (Okay, maybe you want to write that software, but it's a huge undertaking).
Your best bet would be to create a web page that all of the mobile browsers can work on and save a text file from.
Of course it's possible. Bluetooth does this. Wi-Fi does this if you join an ad-hoc network.
Of course it's possible. Just run the Google Docs server on one of the devices.
It might.
Way too vague.