[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH, RFC] x86: make the GDT per-CPU
>>> "Jan Beulich" <jbeulich@xxxxxxxxxx> 11.09.08 14:28 >>> >>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 11.09.08 12:54 >>> >>Firstly, we don't really need the LDT and TSS GST slots to be always valid. >>Actually we always initialise the slot immediately before LTR or LLDT. So we >>could even have per-CPU LDT and TSS initialisation share a single slot. >>Then, with the extra reserved page, we'd be good for nearly 512 CPUs. > >No, this would break 32-bits at least: The GDT entry for the selector >loaded into TR must remain a valid, busy TSS descriptor for the whole >lifetime of the system. So it can't be shared with the LDT. But even for >64-bits I would fear using the same GDT slot for both LDT and GDT >loading. Actually, there's a second aspect here, too (again for 32-bits): As a follow-up patch I'm planning to make the double fault TSS per-CPU, too. This wasn't as simple with the global GDT as it would be with the per-CPU one. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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