Re: VSTa lockups and Shared Libraries....

You (Gavin Thomas Nicol) wrote:
>
> >>I don't really see the need for 2 different systems. I undertand
> >>Andys points about what he wants to see, but I don't know if it's
> >>worth the bother to have 2 different systems, when dll can do just
> >>fine for both. Anyway, as Andy said, "let them who do the work, decide".

Agreed.

> I think PIC is out, even though it would be
> nice. We have to think of a better idea....

How about the following:

Reserve some portion of the virtual address space of each process for
shared libraries. Whenever a process needs a shared library, it is
mapped into this space and immediately relocated. If a second process
needs the same library it just gets mapped into its address space at
the same address. The data segment needs to be duplicated, of course.

User programs could be relocated when loaded or they could use jump
tables.

When the last process using a shared library exits, the space could be
freed again (in this case it is probably better to allocate space in
large chunks (say 4MB) to reduce fragmentation).

We don't need PIC for that, but we have to relocate each library when
it is loaded and the size of all shared libraries in use at once is
limited by the virtual address space.

What do you think?

-- 
|    _  | Peter J. Holzer                       | Think of it   |
| |_|_) | Technical University Vienna           | as evolution  |
| | |   | Computer Science/Real-Time Systems    | in action!    |
| __/   | hp@vmars.tuwien.ac.at                 |     Tony Rand |