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Old 02-20-2007, 03:34 AM   #1
sanyals
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Registered: Feb 2007
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how to re-initialize user space applications without rebooting


Hi,
I want to implement warm restart in the embedded linux system: re-initialize user space applications without rebooting - that is, the kernel loaded in the system should remain loaded.
Is there a known mechanism in linux to do that?
FYI, my kernel version is 2.6.5.
In case you need details, let me know.

Thanks,
sanyals
 
Old 02-20-2007, 05:04 AM   #2
otheus
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Registered: Jun 2006
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re-initializing applications

Many UNIX system services ("daemons") provide for a mechanism of re-starting themselves. The usual mechanism is through signal handling. Simply send the "SIGHUP", or "1", signal to the process and it will (assuming it has been written this way) restart itself. To send this signal, use the "kill" command.
kill -1 pid
If the daemon does not "handle" the signal in this way, it will likely be killed. In that case, you will need to restart the daemon "by hand".

Some daemons that notably do not restart themselves include:
DHCP (from ISC)
YPSERV, YPBIND
Most "interactive" processes will terminate when you send the HUP signal.
 
Old 02-20-2007, 06:03 AM   #3
sanyals
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Registered: Feb 2007
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Great! But my system is as follows:

1. There's only one process in the system and all the applications in the system are as threads in this process.
2. I don't support signal handling!
3. FYI, it's an embedded system - not a desktop one.

Also, even if I succeed to re-init the user space program, how do I re-sync with the kernel again. Is there a standardized technique to do that? Or, I have to do it in a proprietary way.

Thanks,
sanyals
 
  


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