[XCSSA] updating a kernel without rebooting

[xcssa@xcssa.org]

On 8/17/06, xcssa-admin@xcssa.org <xcssa-admin@xcssa.org> wrote:
> http://www.uwsg.iu.edu/hypermail/linux/kernel/0107.1/0313.html
>
> I seem to remember seeing something around kernel 2.4 about it but it was
> experimental and of course you had to have everything setup before your last
> boot for it to work.
.....
> --anton
>
>
> On 8/17/06, xcssa-admin@xcssa.org <xcssa-admin@xcssa.org> wrote:
> > 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?

Linux kernel that conforms to the OSDL's Carrier Grade Linux 3.0 specification,
otherwise, some incredible memorization/knowlege of linux kernel and
associated patches and how everything operates from an assembler/cpu
view per major/minor/subminor release.

....
> > 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/

Yeah, but would he be running what you're interested in?

> >
> > 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?

The general linux releases do NOT have a very stable/consistent system
level API (e.g. see solaris or 'windows') between OS releases, so, not
likely.
Patching aside, just take a look at the difference between dtrace
(solaris) vs systemtap, where one is not patching kernel stuff, but
just profiling/examining a live kernel to get an idea if the issues
involved. (related programs: oprofile, frysk, and/or ltt)
I suppose one could also 'hack' systemtap, but you'd have to roll your
own patches based on kernel level knowledge of what you've already
installed/patched.
Could run your system under a microkernel, then technically, you'd
just be patching a program. ;)

Craig

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March 18, 2006 article : http://linux.sys-con.com/read/193374.htm
Techniques : http://blog.gustavobarbieri.com.br/2006/08/live-patching-techniques.html
Pannus : http://pannus.sourceforge.net/
C program : http://ukai.jp/Software/livepatch/

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