Re: how to force C++ objects to an address? (ABI issue B-7)

[Anthony Heading <aheading at jpmorgan dot com>]

On Mon, Apr 19, 2004 at 10:33:18PM -0400, Ian Lance Taylor wrote:
> Sorry, I switched directions on you.  First I talked about using a
> shared library as you suggested.  Then I switched to not using a
> shared library.

Ah!  I understand then. Thanks.

> Admittedly you lose the advantage of a shared library, as the vtable
> functions are duplicated in each executable rather than shared in a
> single instance.  Unfortunately you may have to give up something to
> get this to work.

It would seem so...

Clutching at straws, if a .so file was already mmap'd into a processes
address space, is there any chance that a subsequent dlopen would
decide to use that existing copy?  (Hmm - that sounds a bit unlikely)

Alternatively, if one were to think about changing Linux to support
this - e.g. creating a variant on dlopen that took an address, or
maybe better using the (unused?) physical address field in the
program headers to indicate where a library should be loaded, or
perhaps less intrusively an extra section to supply that information,
is it realistic to hope this might be acceptable for the wider world?

Rgds

Anthony

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