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Re: kernel DSO


Richard Henderson <rth@twiddle.net> writes:

> On Tue, Sep 14, 2004 at 09:03:28AM +0200, Jakub Jelinek wrote:
> > One is symbol versioning, glibc suddenly looses control of the symbol
> > versions which the vDSO is overriding, so coming up with a new symbol
> > version for one of these functions is hard.
> 
> One possibility here is the symbol forwarding that Sun invented
> recently.  You'd have the version symbol in libc, and the forward
> would point to the VDSO.  Which adds a tiny bit of extra lookup
> during symbol resolution, but no extra overhead when actually 
> using the symbol.
> 
> > The other is that it badly clashes with prelinking.
> 
> Yes, well...  The only solution here is to force conflicts for
> symbols in the VDSO.  I would support adding this as a feature for
> prelink, so that ppc folk could experiment and see if the tradeoff
> is worth it.

Another possibility would be to have the kernel's addresses be
configurable, instead of randomized.  Then when prelinking was
randomizing shared library addresses it could also randomize the
addresses in the kernel.


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