From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Jan Beulich <jbeulich@novell.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: [PATCH, RFC] x86: make the GDT per-CPU
Date: Thu, 11 Sep 2008 14:15:51 +0100 [thread overview]
Message-ID: <C4EED897.26F87%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <48C92E69.76E4.0078.0@novell.com>
On 11/9/08 13:42, "Jan Beulich" <jbeulich@novell.com> 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
prev parent reply other threads:[~2008-09-11 13:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-10 14:35 [PATCH, RFC] x86: make the GDT per-CPU Jan Beulich
2008-09-11 10:54 ` Keir Fraser
2008-09-11 12:28 ` Jan Beulich
2008-09-11 12:35 ` Jan Beulich
2008-09-11 12:42 ` Jan Beulich
2008-09-11 13:15 ` Keir Fraser [this message]
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