lkml.org 
[lkml]   [1998]   [Jan]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Hot swap kernel
Kalle Andersson wrote:
>
> Evening all
>
> I am sorry if I am the 57th asking for this but it would be great to be able to
> hotswap kernels, ie change kernel without needing to reboot.
[...]

A very nice idea, but quite hard to implement. The problem
is that _all_ the data stored by the kernel needs to be
transfered to the new kernel. That is, all the static variables
used everywhere, page tables, process table, file system
mount information and god knows what (possibly outstanding
NFS request information :-), ... Then, of course, the new
kernel has probably changed the semantics of particular
variables or changed the format of particular data
structures, so you need to ``upgrade'' the state to the
new kernel. And, of course, you need different upgrade
modules for different kernel transitions. Imagine the
difficulties of upgrading the state from 1.2.13 -> 2.1.80!
(You can also do it in stages, by chaining together
1.2.13->2.0->2.1 as a _very_ simplified example).

Yuk. Monolithic kernels just don't support this very
well. It might be a lot easier with a microkernel, since
the amount of state you need to deal with is reduced.

Rich.

--
Richard Jones rjones@orchestream.com Tel: +44 171 460 6141 Fax: .. 4461
Orchestream Ltd. 262a Fulham Rd. London SW10 9EL. "you'll write in
PGP: www.four11.com telegraphic, or you won't write at all" [Céline]
Copyright © 1998 Richard W.M. Jones

\
 
 \ /
  Last update: 2005-03-22 13:41    [W:1.080 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site