Re: [Xen-devel] question about system call mechanism in xen

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> "Zang Hongyong" <zanghongyong@xxxxxxxxxx> 17.03.08 15:02 >>>
>hi,
>  I'm interested in system call mechanism in Xen. My understanding (guess) as 
> follows.
>   1)When user application makes a system call, a "int 80" will occur. 
>   2)Then trap to Ring 0 (Which is hypervisor's location). 
>   3)Then hypervisor redirect it to Guest OS's kernel to do system call 
> operation.
>   4)Then back to Ring 0
>   5)back to user appliction
>
>  Is that true?

If everything is 32-bit, "int 80" will be used, but it'll be directed directly
to the guest kernel in ring 1 (i.e. the hypervisor isn't involved).

If the hypervisor is 64-bit, things behave differently based upon what
kind of kernel/app you're running and whether it's a AMD or Intel CPUs
the system is equipped with.

>  Where can I get documents about this question in detail?

Source code is probably the only reference.

Jan


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