Re: Starting a kernel out of a running kernel...

[Jan C. Kleinsorge]

Volker Jung wrote:
> Hello,
>
> is there a solution for starting a new Linux kernel out of a running
> Linux kernel using GRUB or a changed GRUB? First I thought I could use
> LILO. But LILO runs in real mode, not having any idea about protected
> mode. GRUB runs in protected mode itself - in order to boot an OS it
> has to switch back to real mode or to prepare the protected mode
> control registers of the CPU to start the OS. So GRUB may be able to
> pass control from one kernel to the other.
>
> The idea: Instead of using GRUBs abilities to do various things inside
> a shell one could use it to boot a complete Linux. Then one can do
> everything one wants and afterwards one could start the desired system
> WITHOUT rebooting.
>
> Perhaps this sounds crazy but there is a problem where this idea would
> be helpful: So you could implement a read only failsafe system that
> starts again whenever you reset your remote server and out of this
> system (remotely controlled via SSH or similar) you could start the
> desired system WITHOUT having to reboot which would again start the
> failsafe system which isn't the thing one wants. You can call this
> "GRUB with a fully featured OS"...
>
> In LILO this behaviour could be implemented using the -R option - but
> this assumes a read write medium...
>
> Any suggestions?
That is not possible. 'Protected Mode' clearly denotes some form of
protection. Unless you grant the software extra privileges (that is,
write kernel-code)
it's virtually impossible. Apropos 'virtually': Use some virtualization
technology instead and you never will have to reboot any machine again,
ever.
>
> Thanks in advance
> Volker
>
>
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-jan