[XCSSA] updating a kernel without rebooting

[xcssa@xcssa.org]

Hey, I had a question the other day that isn't trivial to answer.  Let
me run it by you.

The main reason Unix systems go down, assuming you have a UPS, is for
kernel upgrades.  What would it take to upgrade a kernel _without_
rebooting?  I may ask this on the linux kernel mailing list at some
point, but I'd see if anyone locally had a handle on this level of
detail.

Obviously we can't just flush everything and start running a new
kernel from the beginning of the boot process; that would be a lot of
work for the same result as rebooting (modulo a minute of time or so).
 But clearly it's okay to, say, flush pages from the buffer cache.
What counts is that processes which were running continue to run
without restart, and maybe that network connections survive (modulo
any timeouts).  Everything else is gravy.

Let the brainstorming begin!  And be quick about it, I want an
implementation by the weekend. ;-)  I bet Bruce Schneier could do
it.... http://geekz.co.uk/schneierfacts/

Anyway, if this could be done, Unix could brag _even more_ about
uptimes.  They'd be damn near forever, and that would really tick
Redmond off, which would make it all worthwhile, don't you think?
-- 
"If you're not part of the solution, you're part of the precipitate."
Unix "guru" for rent or hire -><- http://www.lightconsulting.com/~travis/
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