Messages in this thread | | | Subject | Re: halted system still working as router. | From | Andreas Schwab <> | Date | 30 Oct 1998 12:08:59 +0100 |
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David Woodhouse <David.Woodhouse@mvhi.com> writes:
|> paul.hessels@sheridanc.on.ca said: |> > The power in my apartment went out and my ups was about to fail. I |> > typed "shutdown -h now" <enter>. The machine shutdown and halted. It |> > said, The system is halted, and System Halted. My ups never did die. |> > The curious thing was that when the power came back on I found that my |> > computer was still routing traffic to the internet. Is this normal |> > behaviors for a computer that has been halted? Is this a kernel |> > problem, or specific to my machine(or my kernel)? |> |> It's always been the normal behaviour of the kernel, until someone changed it |> recently in 2.1 kernels without documenting the reason for doing so. |> |> In 2.0, and most 2.1 kernels, 'shutdown -h' will kill all the user-space tasks, |> but the kernel itself will remain alive. As routing is a simple function |> performed by the kernel alone, it will continue to happen. |> |> I've been known to use this fact in embedded systems, which have a custom |> /sbin/init which will set up the interfaces and enable routing, but then just |> exits. (Crack that then) |> |> I keep asking why the behaviour was changed, but nobody seems to have owned up |> to it yet, let alone given their reasons for doing so. |> |> In recent 2.1 kernels, you'll find that the kernel hangs completely after init |> dies. So if you hit SysRq-L, which kills all tasks, you can't even sync and |> unmount your disks before rebooting. I consider _that_ to be a bug.
Then why don't you just call reboot instead of exit in init?
-- Andreas Schwab "And now for something schwab@issan.cs.uni-dortmund.de completely different" schwab@gnu.org
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