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Posted by on June 2, 2006, 10:59 am
I would like to use Linux on an embedded HW and my application requires the
system to start operation as soon as it is switched on.
(As an example, imagine a VCR, which start operation in a fraction of
second.)
I did not seleted the HW yet. I need 4xRS232 port + 4xUSB host interface +
100 MBit/sec Ethernet + Video card + Mouse & Keyboard input + 48 general
purpose parallel I/O lines + (battery operated) + physical dimensions are as
small as possible.
Can you advise me if it is possible to start/boot a version of Linux in
sub-second (100-800 millisecond)?
Do you know any embedded HW with the above specs?
Thanks
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Posted by Padu on June 2, 2006, 12:32 pm
<Sahgu Rugha>
>I would like to use Linux on an embedded HW and my application requires the
> system to start operation as soon as it is switched on.
> (As an example, imagine a VCR, which start operation in a fraction of
> second.)
> I did not seleted the HW yet. I need 4xRS232 port + 4xUSB host interface +
> 100 MBit/sec Ethernet + Video card + Mouse & Keyboard input + 48 general
> purpose parallel I/O lines + (battery operated) + physical dimensions are
> as
> small as possible.
> Can you advise me if it is possible to start/boot a version of Linux in
> sub-second (100-800 millisecond)?
> Do you know any embedded HW with the above specs?
> Thanks
I never worked with embedded linux before, so my opinion may be worthless.
I've implemented an winxp embedded though, and when I was studying it, I saw
one technical article that tackled that issue. What they reccomended was to
implement two on/off buttons, one in the front which is the "soft" switch,
and one in the back of the device, that is the "hard" switch. When you turn
it on/off using the front switch, it only goes to standby (I don't know if
linux has such a mode), therefore with xp embedded the "boot" time is almost
immediate.
Cheers
Padu
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Posted by Unruh on June 2, 2006, 1:38 pm
>>I would like to use Linux on an embedded HW and my application requires the
>> system to start operation as soon as it is switched on.
>> (As an example, imagine a VCR, which start operation in a fraction of
>> second.)
>> I did not seleted the HW yet. I need 4xRS232 port + 4xUSB host interface +
>> 100 MBit/sec Ethernet + Video card + Mouse & Keyboard input + 48 general
>> purpose parallel I/O lines + (battery operated) + physical dimensions are
>> as
>> small as possible.
>> Can you advise me if it is possible to start/boot a version of Linux in
>> sub-second (100-800 millisecond)?
>> Do you know any embedded HW with the above specs?
>> Thanks
>I never worked with embedded linux before, so my opinion may be worthless.
>I've implemented an winxp embedded though, and when I was studying it, I saw
>one technical article that tackled that issue. What they reccomended was to
>implement two on/off buttons, one in the front which is the "soft" switch,
>and one in the back of the device, that is the "hard" switch. When you turn
>it on/off using the front switch, it only goes to standby (I don't know if
>linux has such a mode), therefore with xp embedded the "boot" time is almost
>immediate.
I suppose you could also do it by having a large enough rom so that Linux
entirely fit onto the rom. That way it would simply be a metter of booting
by jumping to the kernel on the rom, and everything is already loaded. The
probem is that rom is liable to be rather slow memory.
Or there could be something to copy everything directly to ram and then
start, but that copying time is liable to be longer than a few
milliseconds.
>Cheers
>Padu
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Posted by Bob on June 2, 2006, 3:31 pm
Unruh wrote:
> >>I would like to use Linux on an embedded HW and my application requires the
> >> system to start operation as soon as it is switched on.
> >> (As an example, imagine a VCR, which start operation in a fraction of
> >> second.)
> >> I did not seleted the HW yet. I need 4xRS232 port + 4xUSB host interface +
> >> 100 MBit/sec Ethernet + Video card + Mouse & Keyboard input + 48 general
> >> purpose parallel I/O lines + (battery operated) + physical dimensions are
> >> as small as possible.
> Or there could be something to copy everything directly to ram and then
> start, but that copying time is liable to be longer than a few
> milliseconds.
The biggest delay is not copying from ROM to RAM, but device
initialization. Trim all unnecessary devices from the kernel. Do
all devices need to be working in 100-800 ms? Or can you boot
with only the critical devices working, and defer initialization of
other devices?
If you are not committed to Linux, you might also want to check
out NetBSD, which will run on pretty much anything that will run
Linux, and may boot faster.
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Posted by will kemp on June 2, 2006, 8:27 pm
On Sat, 03 Jun 2006 00:59:33 +1000, Sahgu wrote:
> Can you advise me if it is possible to start/boot a version of Linux in
> sub-second (100-800 millisecond)?
I regularly put my Linux laptop into suspend, rather than switching it
off. It starts up again pretty quickly from this state - and i'd say that
would be the fastest way to do it. However, as Bob says, initialising
devices is what takes time - along with, of course, reloading the memory
image from the hard drive. Take away the hard drive and have the memory
image on flash memory or something, and that would speed that up, but you
can't start up a system without initialising hardware.
If you can minimise hardware initialisation time, i'd guess, from my
experience of Linux coming out of suspend mode into fully operating
xwindow system, you ought to be able to boot in less than a second.
Will
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>I would like to use Linux on an embedded HW and my application requires the
> system to start operation as soon as it is switched on.
> (As an example, imagine a VCR, which start operation in a fraction of
> second.)
> I did not seleted the HW yet. I need 4xRS232 port + 4xUSB host interface +
> 100 MBit/sec Ethernet + Video card + Mouse & Keyboard input + 48 general
> purpose parallel I/O lines + (battery operated) + physical dimensions are
> as
> small as possible.
> Can you advise me if it is possible to start/boot a version of Linux in
> sub-second (100-800 millisecond)?
> Do you know any embedded HW with the above specs?
> Thanks