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From: Avi Kivity <avi@redhat.com>
To: qemu-devel@nongnu.org
Cc: turnkey-discuss@lists.turnkeylinux.org,
	Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] Merging improvements from VirtualBox OSE into qemu?
Date: Thu, 25 Dec 2008 09:08:38 +0200	[thread overview]
Message-ID: <49533176.4090908@redhat.com> (raw)
In-Reply-To: <4952484F.6010406@turnkeylinux.org>

Liraz Siri wrote:
> I don't really understand the implementation VirtualBox uses to
> accomplish running 64bit VM guests on a 32bit host. Is it possible
> VirtualBox have figured out how to run 64bit instructions on a host
> running in 32bit mode? (otherwise they'll need to be doing some kind of
> emulation)
>
>   

There's nothing magical about it.  Most likely they switch to 64-bit 
mode immediately before entering the guest, and switch back immediately 
after the guest exits.  In effect their turning the host OS into a 
hybrid 32/64 bit kernel (with the vast majority of the code remaining 
32-bits).


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

  parent reply	other threads:[~2008-12-25  7:11 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-24 12:48 [Qemu-devel] Merging improvements from VirtualBox OSE into qemu? Liraz Siri
2008-12-24 13:17 ` Samuel Thibault
2008-12-24 13:26   ` Alexey Eremenko
2008-12-24 13:31 ` Alexey Eremenko
2008-12-24 13:36 ` Paul Brook
2008-12-24 14:33   ` Liraz Siri
2008-12-24 14:51     ` Jernej Simončič
2008-12-24 15:02     ` Paul Brook
2008-12-24 15:29       ` Liraz Siri
2008-12-24 15:40     ` Anthony Liguori
2008-12-24 20:52       ` Liraz Siri
2008-12-25  4:37     ` C.W. Betts
2008-12-25  4:37       ` C.W. Betts
2008-12-25  7:06     ` Avi Kivity
2008-12-25  7:07     ` Avi Kivity
2008-12-25  7:08     ` Avi Kivity [this message]
2008-12-25 14:51       ` Liraz Siri
2008-12-25 16:14         ` Avi Kivity
2008-12-24 23:18   ` Jamie Lokier
2008-12-25  7:11     ` Avi Kivity
2008-12-24 15:23 ` Anthony Liguori
2008-12-24 20:21   ` Liraz Siri
2008-12-24 20:55   ` Liraz Siri
2009-01-05 21:12   ` Frank Mehnert
2009-01-05 22:03     ` Stefan Weil
2009-01-05 23:58     ` Anthony Liguori
2009-01-06  7:41       ` Frank Mehnert
2009-01-06 15:46         ` Blue Swirl
2009-01-06 17:33         ` Anthony Liguori
2009-01-06 20:40           ` Frank Mehnert
2009-01-06 22:17             ` Jamie Lokier

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