Military or Commercial Aircraft Navigation

One of the best articles on how to improve Linux bootup time is here:

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Interestingly, it was done by Sony, presumably for inclusion in embedded devices like their TVs or cameras. It focused on kernel improvements, and reduced that to a subsecond boot, from start of kernel to init process running. The firmware start and user process initialization wasn't the main topic, but there were some suggestion there. The BIOS for Intel processors is one cause of slow behavior, but that wasn't discussed in the paper. Possible ideas for user improvements were presented, but not implemented or measured.

No help for that in a Linux group.

Flight certification is a different topic, and I have heard some comments about difficulty of certifying a Linux based product, but I'm not able to speak to those issues

Reply to
John Haller
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On commercial aircraft or military they have embedded systems that boot up as soon as power is supplied plus the software is a quick boot.

How can the same system be duplicated because it will be used on a boat.

Trouble is the navigation programs are for Windows 95, 98, XP operating systems.

I would like to know if there is any other products out there that can be purchased and software that dose not have to use a PC based board or if it dose has a quick boot up time.

Even if a costmized system has to be made up or even close to this sort of development.

I would like to know what embedded systems aircraft use.

Thanks Russel

Reply to
Russel Millar

Linux is only be a problem on higher criticality platforms, if you are familiar with D0-178B, level C and higher most likely can not use linux because it is not partitionable, or adhere to certain ARINC standards.

On level D, or level E platforms, linux can be used.

Depending upon which avionics systems you are talking about some can take 1-2 minutes to complete boot up. I know radios and displays are generally faster, but hey have higher criticality applied to them therefore the requirements for a quick boot are more stingent.

One thing you may want to look into is how critical the system in question is and develop some use cases and requirements. Depending upon how your system is used and what it's requirements are you may not need a quick boot time, or 30-seconds may be sufficient in which case linux could most certainly be used.

Reply to
seossenk

The big problem with Linux in safety-critical applications is its huge amount of kernel code: because it runs at kernel level, all that code (roughly one million lines) has the potential to cause arbitrary failures, and so has to be classified as "trusted code".

Therefore, if a Linux-based system were to fulfil a function that requires

-say- DO-178B, Level C certification, then the whole kernel would have to be scrutinized according to D0-178B, Level C. This is theoretically possible, but the effort involved is usually far too high to make it a viable option.

Partitioning is not a requirement for safety-critical applications. Rather it is a concept designed to break a given system into multiple subsystems (the partitions) which are decoupled from each other. If one can show that the programs running in the individual partitions are independent of each other, it is permissible to assign individual levels of criticality to each of them.

Yes, except that I would replace "platforms" by "partitions" here.

Instead of turning Linux into a partitioned system, our approach is to put the entire Linux system, i.e. kernel plus userland into its own partition where it serves only level D or level E purposes, while programs with higher criticality levels run in their own isolated partitions in the same machine.

See

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So Linux and safety-critical *is* possible, as long as the safety critical partitions do not depend on the Linux partition(s).

On a typical PC, most of the boot time is spent by the BIOS probing for RAM and peripherals. This can only be influenced by choosing the board or modifying its firmware.

Another large portion of boot time is consumed during userland startup (i.e. loading modules, firing up all those deamons, initializing the GUI, etc.). This is highly configurable and largely depends on requirements (does the system need a GUI/web server/etc.?)

The actual boot time of the Linux kernel is the time between when the bootloader jumps to the linux kernel image and the time when the init process is started. Even with an unmodified kernel, this can be as little as 1-5 seconds, depending on CPU performance.

Rob

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Robert Kaiser                     email: rkaiser AT sysgo DOT com
SYSGO AG                          http://www.elinos.com
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Robert Kaiser

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