Jamie,
Now this is what i'd like to here. Less then 1 sec for startup time
would be absolutely perfect. This device is a hand held radio. The
people using these radios are used to typical analog radios, which at
power on are ready to go immediately. A less then one second boot and
initialization time would be perfect in this case. 30 seconds as
proposed by one of my colleagues at work seems to me to be far too long.
We are looking at operating the processor in the range of 20 to 40MHz.
Our project is a hard disk and network video player, with a 166MHz ARM.
It boots uClinux in about 15 seconds (12 if we tweak it) from the
moment power is applied to playing high-def video from hard disk. A
surprisingly long part of that time is decompressing kernel, modules
and application into RAM ready to run, and the IDE detection time.
Not decompressing is slower, as flash reading is quite slow.
Depending on the flash device execution from flash is not out of the
question. I've researched some flash devices that will only need one to
no wait states for execution. As an example the MPC55xx has on board
flash with zero wait states. The flash execution time depends on the
device selected for the system. Just a matter of cost. I'm thinking
the problem domain might be a little different. We don't have a hard
disk and the processing required is not as intensive as a video device.
We've had an x86 Linux system, on a standard fast PC motherboard, doing
something similar with a similar power-to-video time.
So you really don't need to wait 30 seconds, even on a PC.
A 1 sec boot would be lovely, but I don't see how we could achieve it
without redesigning our hardware. It takes longer than that for the
chips to reset then read the flash decompressing to RAM (kernel,
modules, busybox, main app). The apps would run far too slowly direct
from flash. There is no MMU to demand-decompress-read (which would be
a nice trick if possible). I think we could get it down to 5-10
seconds with much work and fine tuning.
XIP - execution in place with some of the items form the celinux site
seem like a great collection of 'technologies' to achieve the less then
one sec power up time.
thnx - bob
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title:Senior Embedded Systems Development Engineer
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