How to save core images ???

[Doug Gwyn <gwyn>]

> Very interesting that this hasn't come up before (or has it?).  It has
> always amazed me that this is not a standard feature of all operating
> systems, and I have had to implement various kludges over the years to
> enable checkpoint/restart capabilities.

Yes, it has come up several times.  Nobody has answered the most
fundamental objection, which is that the state of a process really
includes the state of pipes to other processes, the state of the
terminal, the state of files, etc. so that virtually the entire
system would have to be checkpointed to provide a working general
facility.

There have been numerous attempts to checkpoint UNIX processes
from user mode, but to do it right you would need the help of
the kernel (since the code being checkpointed is still undergoing
modification during the checkpoint process, otherwise).

Apart from saving a bit of work in initializing large amounts of
data, why do you feel this feature is necessary?