Re: ppc64 vDSO in mainline

[Roland McGrath <roland at redhat dot com>]

> On Sun, 2005-03-13 at 00:56 -0800, Roland McGrath wrote:
> > The cache flush entrypoints you are talking about are for the dynamic
> > linker's own use in relocation, right?
> 
> Yes, and also for things like Mozilla/Oofice/XFree/JVM/etc... (I don't
> think there is a standard glibc function to expose this functionality
> though, and I would like to avoid those guys to "know" how to directly
> call into the vDSO, so it may be useful to define something.

Those outside users are a separate issue and basically the same thing as
the other vDSO entry points you want such as system call replacements.

The thing you can make progress on right away is making relocation use them.
So I'd suggest you try to make that work and put forth a patch for it.

> >   If you would like to see the dynamic linker point the function
> > descriptors it sets up directly at your entry points, then we'll have to
> > work on that plan.
> 
> That would be interesting to obtain that result yes. I don't know enough
> about the guts of the dynamic linker to dare hacking that myself for
> now, but at least, now we have a base to work from.

We the maintainers of the dynamic linker would have to put some effort into
coming up with the right ways to do this.  But we'd need to have a good
motivation for such effort, which as yet does not exist outside ppc64.

> Sure. If you want me to tweak the kind of informations the ppc vDSO
> exports in anyway, don't hesitate to ask.

If we decide what information we want, then I will implement the
presentation for the x86 vDSO to test out the ideas.  Then we can check
those with you and other architecture maintainers to see if anything
prevents them from being used across architectures, or could be done better.


Thanks,
Roland