> Well the hardware should not matter and the startup code should be  
> finished in
> several milli seconds, of course.
> Most probably are ARM. PPC or SH4 platforms used in automotive  
> devices.
> In the automation industry the boot time is not that important -  
> therefore a
> lot of PC compatible boards are used.

The reason I ask about the hardware is so that I can figure out if you  
are trying to boot a standard PC in that amount time or not. I don't  
know your level of understanding in these matters so that's why I ask  
for more information. I was the MIPS maintainer on RTAI for a couple  
of years, and we had a very wimpy MIPS board and it would boot up and  
start our application in about 2 seconds. Now, with the kernel  
executing in place that time was significantly lower but ROM access  
was very slow and this affected realtime performance. That's why I had  
to go with copying the kernel to RAM. If I recall it would boot up in  
under a second, but that's significantly more time than the 50ms you  
are asking about.

On the other hand that really was a weak chip. 66MHz VR4181. Ugh. We  
mainly wanted it for the low power draw.

Gilles pointed out that you could start a kernel based xenomai  
application fairly early but userspace support takes more time to get  
up. If you really want to get a fast boot time then try to link your  
kernel to execute in place if the hardware supports it.



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