Fast shutdown

William A. Gatliff bgat at
Sat Nov 16 08:10:01 EST 2002

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,

Bill Gatliff
Embedded systems and Free Software.  Yea, it *is* all that!
See for details.

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