Slashdot Mirror
Linux Gains Native RTOS Emulation Layer
nerdyH writes to tell us that the Xenomai/SOLO project is attempting to deliver VxWorks and other RTOS emulation for any Linux kernel. "Some weeks ago, I started laying the groundwork for porting the Xenomai emulators natively over the PREEMPT_RT kernel. Unlike the co-kernel based Xenomai version, SOLO does not require any kernel support from additional modules or patches. It is fully based on the standard POSIX library, and runs as a regular process controlled by a single image Linux kernel. As a first step, a VxWorks emulator has just been rebuilt over this new framework."
don't click that link, mod parent down.
> Another important asset of an RTOS is well defined task preemption: No task gets preempted by one with worse priority. Time slicing might be enabled so that a task gets preempted by one of the same priority, and better priority tasks always preempt if they are ready to go.
Any normal distro Linux kernel can do this particular part. Just set the scheduler to round robin. (You can do this in KDE4 btw. Press ctrl-esc to bring up the task manager, right click a process, change priority, and chose round robin.)
FFS don't click that link - it's some sort of browser spawner/malware/virus.
.exe - luckily on my mac that did nothing.. that's the virus payload I guess
I had to power cycle my machine to shut it down as it managed to completely saturate the machine.
As far as I can tell it:
1. Tried to log me onto a gay porn site
2. Tried to open up IRC and do something (failed, luckily, since osx won't let such things happen automatically.. my screen just filled boxes asking if I wanted to start colloquy)
3. Tried to run a
I reckon if you clicked that button on a windows machine you'd be crying right now - and your passwords would be all over IRC too...
No, it's Lord Haw Haw's Yahoo link that's attacking windows machines. /. to running such a thing :)
But then, who in is right mind would admit on
"The likes of Facebook and WhatsApp are free to those whose privacy is of zero value."
The problem with VxWorks is that the scheduling accuracy is its only positive feature. Device drivers are rare and expensive, probably because it doesn't have a sensible hardware abstraction layer like Linux, Windows (NT family), and QNX. If you want to use the MMU on the processor you get charged again, and you get even more incompatibilities. The documentation doesn't go into much depth, and Google isn't very helpful, as hardly anybody talks about it on the Internet.
Have you tried QNX or RTEMS? I don't have any data on their scheduling accuracy, but they claim to support the same real-time features. I've also found the QNX documentation much easier to follow, and I managed to turn out a BSP and a custom device driver within a week of first receiving the software.
Oh yes I've coded for it. I'm on my second BSP and my third kernel. It's not as bad as it used to be in some respects. The Eclipse is the IDE now. The documentation is still horrendous though. WindRiver is working hard on their own RTOS Linux solution. I don't know if they are planning on eventually digging a hole and throwing VxWorks in it, or just trying to combat the free RTOS Linux market with something they can sell to managers.
I also opened the link without thinking -- and then power cycled. After powering up again and reviewing Firefox's sessionstore.js, I believe the link leads to a URL of the form "http://members.on.nimp.org/index.php?steal=1&key=XXXXXXXXXXXXXXXX". (The X's appear to be a hexadecimal code, but I'm not sure what the meaning of the code is.) The content of that page is:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<title>GNAA Last Measure Live!</title>
<meta name="keywords" content="bsd digg gay gnaa internet last measure linux nigger slashdot freebsd niger internet providers internet service providers nigga gays niggers openbsd internet access cable internet xandros netbsd gai gay sex gay personals bds gaysex enternet dial up internet cable internet service lunix internets gay black men internet services cheap internet service gay chat rooms internet fax service insmod gey internet radio dial up internet access international internet gay massage inux gay movies gay com gayboy internet business internet businesses homosex internet college internet banking schwul internet gambling neger homosexuales internet poker internet filtering satellite internet connection internet roaming gay cock broadband internet access gay adoption asian gay gay bears gay guys linux on windows internet connection schwule gej maryland internet linux recovery gay sites michigan internet remote internet access making money on the internet gay pornography gay hardcore internet speed up atlanta gay internet game older gay men gay nudist gay shopping gay san francisco houston internet california internet nigga stole my bike gay houston gay marriage gay bear internet auctions internet worldwide linux laptops redhat9 internet billing broadband internet linux drivers linux pc gay amsterdam gay seattle gay bdsm selling on the internet mature gay men internet call gay sex chat internet marketing gay toys internet printing linux help freebsd ports mobile internet linux for windows linux clustering gay chat teen gay porn ny gay alabama gay freebsd 6.0 linux os spain internet clips gay hairy gay men gay leather make money on the internet gay boy gay philadelphia gay community internet via satellite freebsd 6 gay cartoons gay love nigga lyrics niger uranium internet search gay news hate niggers gay georgia oral gay sex linux downloads communication internet niger africa bds suspension gay nude boys linux applications gay pics enternet 300 internet censorship internet information server gay australia redhat linux gay niggers niger forgeries gay phoenix gay orgies internet sites aspergillus niger internet traffic oracle linux gays fucking linux support test internet internet messaging gay vivo horny gay the internets niger forgery bds marketing freebsd org sex gay movies internet canada niger yellowcake gay women linux apache the niger river freebsd wireless internet development bodybuilder gay freebsd java can a nigga get a table dance gay latinos deng gai linux penguin realest nigga real nigga roll call linux tutorial japanese gay gays in military freebsd screenshots linux systems linux software freebsd apache joseph wilson niger installing freebsd gay store freebsd update freebsd port freebsd upgrade teen gays install freebsd freebsd cvsup dead niggers cumshot gay ten little niggers gays com freebsd laptop fuck your couch nigga broke nigga internet stock trading niger document jews spics wtc jew jewish holidays jewish calendar jewish community center anti semitism single jews jewish names jewish history jewish museum jewish hospital jewish wedding bernanke jewish us jews jewish music jewish federation barnes jewish russian jews jewish jokes libby jewish jewish singles jewish religion barnes jewish hospital long island jewish jewish people jewish news jewis
RTEMS is a free, open source alternative to VxWorks that provides POSIX threads in addition to an API we call the "Classic API" that was based upon an old dead proposed VITA standard from pSOS+ folks. RTEMS is single process, multi-threaded in the POSIX sense and has almost every POSIX 1003.1b features that is possible without being able to exec a new process. We use GNU tools and maintain an APT/Yum repository so GNU/Linux users have an easy situation with the tools. Check out some of the places it has been used at http://www.rtems.org/flyers.html and in the Wiki Applications page. You can get predictable tasking and algorithmic behavior while still staying in the free software world.
What's worse, the link (that Slashdot shows as a Yahoo link) is actually an only slightly obfuscated Nimp link.
Aside, I find it amazing that a 4 letter TLD is allowed to be used this way as long as it has. Nimp isn't just a shock site, it's got to break enough criminal laws to put it's owners and people that link to it in jail.
I don't think you should be speaking against RTOS without any actual RTOS experience. It just makes everyone else assume you're an ass.
These things typically run on embedded devices, not a friggin' Dell midtower. They do one job and they do it with exacting accuracy, on minified motherboards and fanless CPUs, hooked up to custom-built controllers and monitoring equipment.
RTOS tasks are typically things we used to do in solid state with simple feedback logic, but the RTOS allows it to be done in software at a lower cost, plus allowing easy updates or adjustments without a complete redesign.
-Billco, Fnarg.com
Another problem I have seen in VxWorks is the priority inheritance: It doesn't work correctly for nested locks: A low priority task takes a lock A, runs it's own code for and then it calls into say a driver and takes lock B. Now some high-priority task wants to access the same driver and tries to lock B. The first tasks is then boosted in priority and soon finishes the driver call and unlocks B. But it is not unboosted before it release A. That is a huge problem in a RTOS: Suddenly the timing of the high priority task depends on how long a low priority tasks keeps the completely irrelevant lock A. You don't get the decoupling, that the timing of a high priority tasks only depends on the tasks of equal or higher priority, which is so important in a RTOS.
Basicly, I think core of Linux with PREEMPT_RT is a better (more deterministic) RTOS than VxWorks, but slower (longer maximum latencies for especially interrupts); but all subsystems around the scheduler etc. aren't coded for RT use - i.e. it has non-deterministic code-paths and might even make blocking calls. So an RT application on Linux/PREEMPT_RT can basicly only use basic highres timers, simple serial ports and memory mapped devices. Use of the netstack, disk IO is a no-go. But then again, the same applies to VxWorks...
I'm running NoScript Firefox extention under Linux and while my retina hurts, there was no moving screens or whatnot. By default, I do not trust javascript/activex. Get NoScript and configure it!
http://noscript.net/
QNX used to be intel-only, but has been ported over to other chipsets. I know I've used it on an arm and some ppc before.
I have asked Wind River representatives whether their Linux product is meant to replace VxWorks and they emphatically said no. (If that means anything.)
Breakfast served all day!