John Baldwin wrote:
>
> On 28-Dec-00 Poul-Henning Kamp wrote:
> > In message <[EMAIL PROTECTED]>, "Walter W.
> > Ho
> > p" writes:
> >>Hi all,
> >>
> >>I was wondering how to increase the robustness of the booting process,
> >>so that a box would be able to keep itself on its feet without
> >>intervention of the console. I think this would be of great value to the
> >>many people who administer colocated boxes.
the old 'nextboot(8)' system used to do this if you had the 'writeback'
option enabled..
it wrote a sequence of boot strings into block '1' (not 0)
and zero'd them out as it used them up.
/etc/rc would then be used to write an appropriate set of strings back
in the case of a successful boot.
This is used successfullly in the thousands of interjets out there in
the field. Unfortunatly the new bootblock writers never considered
this an important enough feature to emulate.
but it gives you a place to look.
We wrote a list of ever-increasingly conservative boot strings, eventually
even moving to an alternate root partition....
> >>
> >>I'm not much of a coder so all I can do is mailing this (at the risk of
> >>wasting your time with total useless crap ofcourse, in which case I
> >>apologize.)
> >>
> >>1. Old kernel recovery
> >> When 'make install'ing a new kernel, a flag is raised (say,
> >> 'revert_on_fail') which is only cleared after a successful system
> >> initialisation. When the new kernel boots, a panic in this state or
> >> an unexpected reboot (reset after a system hang) would cause
> >> /kernel.old to be loaded on the next boot instead (maybe the same
> >> could work for /etc/rc.conf.old)
> >
> > This is actually more a question of where to store the flag than
> > anything else.
>
> /boot/loader.conf perhaps, but how does the loader know that the previous boot
> failed so that it knows to fall back? This is much harder, as a failed kernel
> boot usually results in a hang or an instant CPU reset.
>
> --
>
> John Baldwin <[EMAIL PROTECTED]> -- http://www.FreeBSD.org/~jhb/
> PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
> "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
>
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( OZ ) World tour 2000
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