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Re: [Xen-devel] [PATCH, RFC] x86: make the GDT per-CPU
| To: | Jan Beulich <jbeulich@xxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] [PATCH, RFC] x86: make the GDT per-CPU |
| From: | Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |
| Date: | Thu, 11 Sep 2008 14:15:51 +0100 |
| Cc: | xen-devel@xxxxxxxxxxxxxxxxxxx |
| Delivery-date: | Thu, 11 Sep 2008 06:16:23 -0700 |
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| Thread-topic: | [Xen-devel] [PATCH, RFC] x86: make the GDT per-CPU |
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On 11/9/08 13:42, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote: >> 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. Well, the extra LGDT looks like it will take about 130 cycles on Core-2 hardware. I suppose that is tolerable. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel |
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