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Re: [Xen-devel] why xen use x86_emulation() in page_fault



Hi, 

At 21:46 +0800 on 11 Oct (1318369564), cc Luit wrote:
> On Tue, Oct 11, 2011 at 8:04 PM, Zhengwang Ruan (Royo) 
> <zhengwang.ruan@xxxxxxxxx> wrote:
> > 2, Real-mode code you talked above is used to execute the first 16-bit
> > initial code of a guest OS? Does it have other usages in current Xen
> > implementation?
> >
> I'm also curious about the real-mode, looking forward to the replay~

It is used whenever the guest OS runs in real mode.  That's usually just
for a short while in the boot loader and the start of the kernel, but
that would depend on what OS you run in the guest.  DOS, for example,
would use it all the time. :) 

Linux (like most modern OSes) avoids real mode once it's booted, but if
it ever needs to reset a CPU (e.g. if you support CPU hotplug) then that
CPU will run in real mode briefly after it's reset.

Tim.

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