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There's a lot of prior art for this. Various telco switches had this capability... Ericsson
AXE switches did at least... how much this was used or ever worked though, I'm not sure.
Ksplice: kernel patches without reboots
Posted May 1, 2008 15:00 UTC (Thu) by Lennie (subscriber, #49641)
Just out of curiosity...
the comment above said:
'Well, erlang has this feature since the middle of 90s, so that's a prior art too...'
And I know Erlang was created by Ericsson.
Would it be wrong to conclude the switches might have been running Erlang ?
Posted May 1, 2008 23:24 UTC (Thu) by stewart (subscriber, #50665)
they weren't... Ericsson is pretty big, so lots of things happen and there's certainly been
more than one programming language invented there. I was thinking of PLEX, used in AXE
Posted Jun 11, 2008 22:13 UTC (Wed) by telcoman (guest, #52500)
Yes, Ericsson, Siemens and possibly many other telco manufacturers use the same solution for
decades. So MS's patent is likely to be invalid.
Patching is a very good thing, as long as you apply the right patches. Just remember the
Ericsson scandal: http://www.spectrum.ieee.org/print/5280
So being able to patch a running kernel is a double edged sword. If someone gains root rights
he can apply a nasty patch secretly and leave immediately.
In most HA systems there is an alternative of patching. On resilient systems you have quite
enough hardware, so all you need to do is update the code (even the most frequently used ones)
on a spare computer, move all the data (incl. data from RAM) there and continue the execution
using the new code (or new hardware, if you had HW issues instead of SW ones). That is how
Nokia DX200 switches work. The same restrictions apply for data structure changes as for
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