Re: Persistence Pros and Cons

[ness]

Ludovic Courtès wrote:
> "Christopher Nelson" <address@hidden> writes:
>
>
> > Ah. Well, it seems to me that capabilities must not be serializable.
> > If they could be, what would stop a thread from modifying the
> > capabilities as they flowed back to the kernel?
>
>
> Right.  I was assuming a _protected_ capability systems where
> capabilities are by definition _not_ serializable by applications[0].
>
>
> > If the serializing entity was part of the TCB, then you have to
> > implement a certain amount of persistence anyway.
>
>
> That was my point: how can we serialize capabilities without support
> from the trusted kernel (i.e. without "persistence").  As you say, it's
> probably impossible.  This makes the use of persistence more than just a
> matter of taste.

The capabilities can't directly be serialized. The application has to 
get (e.g. by inheritance).
I guess jonathan meant the application level state.

> > Once you start implementing persistence by degrees you run into a
> > whole bunch of edge cases where it's just easier to implement
> > system-wide persistence anyway.  That's been my experience, in any
> > case.
>
>
> I guess so.  Have you been working on persistence/checkpointing
> mechanisms?
>
> Thanks,
> Ludovic.
>
> [0] http://lists.gnu.org/archive/html/l4-hurd/2005-10/msg00010.html
>
>
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