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authorJeremy Fitzhardinge <jeremy@xensource.com>2007-07-17 18:37:06 -0700
committerJeremy Fitzhardinge <jeremy@goop.org>2007-07-18 08:47:44 -0700
commit8b84ad942b534f8faeb34b68f0f7277ea375fed0 (patch)
tree911472add5b9068a95a77215a70dac63edf6202e /include/xen/hvc-console.h
parentd66bf8fcf3fce058a1cd164a7c8ee6093fdf039c (diff)
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xen: hack to prevent bad segment register reload
The hypervisor saves and restores the segment registers as part of the state is saves while context switching. If, during a context switch, the next process doesn't use the TLS segments, it invalidates the GDT entry, causing the segment register reload to fault. This fault effectively doubles the cost of a context switch. This patch is a band-aid workaround which clears the usermode %gs after it has been saved for the previous process, but before it gets reloaded for the next, and it avoids having the hypervisor attempt to erroneously reload it. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Diffstat (limited to 'include/xen/hvc-console.h')
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