[pypy-dev] Questions for Armin

[Armin Rigo]

Hello Bengt,

On Sun, Jan 19, 2003 at 04:26:24PM -0800, Bengt Richter wrote:
> >This might probably be done without Psyco, and would certainly be a nice thing
> >to have.  Note that a good Psyco could remove any need for it: most
> >initialization code could theoretically be specialized into something that
> >just creates the necessary data structures without executing any code at all.
> 
> There seems to be something I missed. Could you clarify how such specialized
> versions persist so they don't have to be redone? I.e., how do you get from
> an original .py source-only representation to the specialized form, and how
> does the latter come to exist? I.e., is this a new form of incrementally
> updated .pyc?

Yes, you must have this data persist somewhere.  In a .pyc-like file or any
variant of the idea (like having one "global" database as Edward proposed,
which would be user-specific to avoid security issues).

> >Sometimes I like to point out that if our OS were written in a high-level
> >language with built-in specializers, they would boot in no more than the time
> >it takes to do the actual I/O that occurs when booting (mainly displaying the
> >login screen and waiting for mouse, keyboard and network input) --- everything
> >else is internal state and can be done lazily.
> 
> If this means dynamic incremental revisions of system files, it must be a whole
> new class of security issues to nail down, or am I misconstruing?

Yes and no.  There are tons of issues that must be carefully planned for such
a thing to be possible and secure, and it is probably not possible in a
Unix-style OS (which is essentially C).  I'll just drop the link 
http://tunes.org as an example of what I mean by re-planning an OS.


A bientôt,

Armin.