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Re: [Xen-devel] Paravirtualization of the "HLT" instruction (for example

To: Ian Brown <ianbrn@xxxxxxxxx>
Subject: Re: [Xen-devel] Paravirtualization of the "HLT" instruction (for example) on x386
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 12 Jan 2006 10:36:13 +0000
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On 12 Jan 2006, at 09:27, Ian Brown wrote:

So I tried to find where in the Xen-3.0 code it is done.
I saw in vmx.c the vmx_vmexit_do_hlt() method ,which is called
when "HLT" is performed,  but this is relevant when running a
platform with VT-x.
I am looking for tracing where this handling or modifying of
the HLT instruction is done in a usual x386 (non-VTX) processor.

Can anybody please point where in the code of Xen 3.0 this is done
(for x86 processors)?

The point of paravirtualizetion is that such instructions are replaced with explicit traps to the hypervisor in the OS. Emulation of the raw instruction is not required.

In fact we do emulate some privileged instructions, just not HLT.

 -- Keir

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