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secondary kernel in linux

Posted on 2003-10-30
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Can I know the details and how the things really happen in

EMBEDDED LINUX READY FOR REAL TIME

Two main approaches exist for meeting real time response requirements in a linux system

1.Brute force(real_fast) application of processors power.

2.The insertion of secondary kernel’s that virtualize the cpu interrupt change and manage real time events and processing, leaving linux to run(or not)as a lower priority task under the second kernel.

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Question by:vinil_nvk
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by:Gns
ID: 9651677
First one need understand what "Real Time" means here (when referring to linux in conjunction to "real time operating system" (RTOS)).
Simply put Real Time is achieved when a (user) process can rely on certain system calls returniing within (given) hard timelimits, so that it can depend upon "things" not taking longer than this... Very important in timing critical embedded functions.

With this in mind, #1 would then achieve "Real-Time" by having so much raw CPU "power" that the timing constrints never come close to be exceeded. This might be constued as ... dicey... but in controlled environments should be able to work OK.

#2 would imply linux running as a "host OS" to some real-time-capable RTOS. Kind of like vmwareish...

"Famous" RTOSes would include OS9, QNX, OSE ... And RTLinux, patches etc to make linux be able to meet timing constraints... So a google search for RTLinux (also look at http://www.tldp.org/HOWTO/RTLinux-HOWTO-3.html ... More eloquent than litlle ol' me:-).

-- Glenn
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by:vinil_nvk
ID: 9657673
yeah, thanks for the answer, but still can I have what basically do I need to know if I want to program for a RTLinux? Considering me as a know nothing of RTLinux, What amount of time do I need to spend in days to get to it?
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Gns earned 100 total points
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http://www.tldp.org/HOWTO/RTLinux-HOWTO-4.html and http://www.tldp.org/HOWTO/RTLinux-HOWTO-5.html shoiuld show you some of what it would entail.
Assuming you're not a "knownothing" programmer this should show too that the effort is rather limited;-).

-- Glenn
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by:Gns
ID: 10182756
I think I've answered in enough detail.

-- Glenn
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by:Karl Heinz Kremer
ID: 10231585
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:
Answered by Gns
Please leave any comments here within the next seven days.

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!

khkremer
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