Re: unhandled vm exit: 0x9

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Omar Khan wrote:
> hi, 
>    I am trying to run an experimental operating system 'Choices' on kvm and it
> is giving me the 'unhandled vm exit: 0x9' error. It runs fine with the -no-kvm
> switch though. In an earlier post
> (http://article.gmane.org/gmane.comp.emulators.kvm.devel/
> 654/match=unhandled+vm+exit) Avi said that "Exit 9 is a hardware task switch,
> which is not supported by vmx" Can someone please elaborate on this. Also any
> ideas on how to handle this?
>   

x86 supports a hardware task switch mechanism, almost an OS in 
hardware.  As no modern OS uses it, vmx (as well as svm and x86-64) does 
not support it.

There can be two causes for this:
- your OS actually uses the hardware task switch mechanism.  in this 
case, you need to emulate its behavior in kvm.
- some bug in kvm caused this to be triggered accidentally.

You can determine which case you're seeing by adding a printf() to the 
qemu task switch emulation and running with -no-kvm.  The place to put 
it is probably switch_tss() in target-i386/helper.c.

-- 
error compiling committee.c: too many arguments to function


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