| Date | Thu, 15 Feb 2007 22:06:37 -0800 | From | Zachary Amsden <> | Subject | Re: [patch 13/21] Xen-paravirt: Add nosegneg capability to the vsyscall page notes |
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Jeremy Fitzhardinge wrote: > Add the "nosegneg" fake capabilty to the vsyscall page notes. This is > used by the runtime linker to select a glibc version which then > disables negative-offset accesses to the thread-local segment via > %gs. These accesses require emulation in Xen (because segments are > truncated to protect the hypervisor address space) and avoiding them > provides a measurable performance boost. > > Signed-off-by: Ian Pratt <ian.pratt@xensource.com> > Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk> > Signed-off-by: Chris Wright <chrisw@sous-sol.org> >
Acked-by: Zachary Amsden <zach@vmware.com>
We would like to see this by dynamic, but that is much more difficult to achieve, and seeing your recent linker issues, I don't think this should gate merging this code. The performance loss for us I believe to be negligible, and the fix is quite a bit more complicated than something achievable in the .21 timeframe.
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