Fast shutdown

Fast shutdown

[GOTZON ASTONDOA]

Hi all:

	Our custom board has to microprocessors: 68K and PowerPC. We have
instaled Linux in the PowerPc side.
	When the user suddenly shutdowns the board, the 68K sends an
interrupt to the PowerPC.We have more or less 8 mSeg to close all the Linux
system (it has hard disk, ethernet, ftp and our own application).

	Can somebody tell me any idea to close the Linux system in the
fastest way? We are thinking in capture the interrupt signal, but, is it
enough fast?

Thanks for your help in advance.

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Re: Fast shutdown

[William A. Gatliff]

On Tue, Nov 12, 2002 at 04:04:39PM +0100, GOTZON ASTONDOA wrote:
>
> Hi all:
>
> 	Our custom board has to microprocessors: 68K and PowerPC. We have
> instaled Linux in the PowerPc side.
> 	When the user suddenly shutdowns the board, the 68K sends an
> interrupt to the PowerPC.We have more or less 8 mSeg to close all the Linux
> system (it has hard disk, ethernet, ftp and our own application).
>
> 	Can somebody tell me any idea to close the Linux system in the
> fastest way? We are thinking in capture the interrupt signal, but, is it
> enough fast?


You'll probably want to dump /sbin/init, at least.

Just throwing something out for starters....

You could have an interrupt handler watching the signal from the 68k,
and sending a message via named pipe (perhaps) to a userspace program.
The userspace program would signal all your other programs, sync(),
then wait for powerdown.

I think you'll want all your processes doing synchronous i/o, so that
you don't have much in the way of unwritten disk data to worry with.
You'll probably also want a journaled filesystem, for those times when
8ms just isn't enough...

Hope this gives you a good starting point,


b.g.
--
Bill Gatliff
Embedded systems and Free Software.  Yea, it *is* all that!
See http://billgatliff.com for details.

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Re: Fast shutdown

[Amit Chaudhary]

William A. Gatliff wrote:

> On Tue, Nov 12, 2002 at 04:04:39PM +0100, GOTZON ASTONDOA wrote:
> >interrupt to the PowerPC.We have more or less 8 mSeg to close all the
> Linux
> >system (it has hard disk, ethernet, ftp and our own application).
> >
> >	Can somebody tell me any idea to close the Linux system in the
> >fastest way? We are thinking in capture the interrupt signal, but, is it
> >enough fast?
>
>
>
> You could have an interrupt handler watching the signal from the 68k,
> and sending a message via named pipe (perhaps) to a userspace program.
> The userspace program would signal all your other programs, sync(),
> then wait for powerdown.

Another option is mount the main fs as readonly, put in a robust
recovery for any config data fs and use something equivalent of a reboot -f.

Amit


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