Re: [Xen-users] 64bit dom0, 32bit domU, glibc?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> > The TLS refs problem happened because 32-bit Xen and glibc both want to
> > do crazy things with the processor's segmentation hardware.  32-bit Xen
> > needs the segmentation for its own protection.
> >
> > 64-bit Xen doesn't protect itself using segmentation, so it's not
> > necessary to do anything to prevent a conflict with glibc.
>
> That old problem also seemed to involve the libraries in /lib/tls. It
> was easy to just move them aside to /lib/tls.old, and current versions
> of RedHat kernels drop a little file called "kernelcap" in
> /etc/ld.so.conf.d/ that helps prevent the use of those libraries.

Yes, recent Xen-friendly distributions don't need the TLS libraries to be 
manually disabled because they handle it themselves in an appropriate way - 
even on 32-bit Xen.

But this isn't necessary on 64-bit, so glibc is free to use segments in funny 
ways (which I think is intended to produce a performance benefit, but from 
what I've heard it's doubtful whether you'll actually notice it).

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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