Re: [Xen-devel] Re: NPTL/TLS "emulation" idea (fwd)

[David Hopwood <david.nospam.hopwood@xxxxxxxxxxxxxxxx>]

Jakub Jelinek wrote:
> On Wed, Oct 20, 2004 at 06:27:39PM +0100, Keir Fraser wrote:
> > > On Wed, Oct 20, 2004 at 12:55:22PM -0400, Rik van Riel wrote:
> > >
> > > >   4. Provide an alternative libc that does the +ve accesses (which are
> > > >      libc private, afaik) in another segment.  This does not break the
> > > >      ABI for userland programs and -ve accesses aren't that bad when
> > > >      there are no +ve accesses in the same segment.
> > > No, the ABI uses -ve accesses and %gs:0 (4 bytes there), +ve accesses
> > > above +4 are glibc private.
> > Could we duplicate %gs:0 at %gs:-4 and update the ABI? Or is the ABI
> > now set in stone?
> The ABI is there for several years, used e.g. in Solaris as well
> and is used already in several libraries, not just glibc.
> The ABI is not going to change for the sake of emulators.
This aspect of the TLS ABI has also been a problem for L4, although for
a different reason (they had already used %gs:0 for something else).
I can't immediately see any solutions arising from that discussion, but
in case it gives anyone else an idea, see
<http://lists.ira.uka.de/pipermail/l4ka/2004-March/000874.html>.

Looks like the same problem is also going to come up for the AMD64 port:
<http://lists.freebsd.org/pipermail/freebsd-threads/2004-March/001850.html>

--
David Hopwood <david.nospam.hopwood@xxxxxxxxxxxxxxxx>



-------------------------------------------------------
This SF.net email is sponsored by: IT Product Guide on ITManagersJournal
Use IT products in your business? Tell us what you think of them. Give us
Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more
http://productguide.itmanagersjournal.com/guidepromo.tmpl
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel