Re: [Qemu-devel] Qemu and (Pacifica | Vanderpool)

[Anthony Liguori <aliguori@us.ibm.com>]

Paul Brook wrote:

>On Sunday 06 November 2005 15:19, Dave Feustel wrote:
>  
>
>>Will Qemu be modified to take advantage of the hardware virtualization
>>facilities incorporated in AMD's Pacifica and/or Intel's Vanderpool
>>technogies?
>>    
>>
>
>qemu is an emulator, not a virtualizer, so these extensions don't really help.
>  
>
Not quite.

qemu is technically a JIT.  kqemu/qvm86 are virtualizers.  Bochs is an 
actual emulator.

VT/SVM will definitely improve the performance of kqemu/qvm86.  The only 
bottleneck left in QEMU would be the IO emulation.  Since Xen uses the 
QEmu IO model any performance improvements for Xen IO emulation should 
be sharable with QEmu...

>You may want to look at Xen (www.xensource.com), which already supports these.
>  
>
Xen is a Type I VMM, QEmu is a Type II.  They aren't interchangable.

The main difference between a Type I and a Type II VMM is that a Type I 
runs on bare metal (and has control of the entire platform) whereas a 
Type II VMM runs within an Operating System.

The "Analysis of the Intel Pentium's Abiliity to Support a Secure VMM" 
paper has a good discussion of the differences between the two (the 
original Popek/Goldberg paper is pretty dense).

Regards,

Anthony Liguori

>Paul
>
>
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