RE: [Xen-devel] Why using hypercall_page ?

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Wu Bingzheng
>Sent: Thursday, October 23, 2008 9:18 AM
>
>Hello,
>
>I am studing Xen hypercall now. I found that hypercall is invoked via
>hypercall_page, which is only filled with (in
>no-hypervisor-kernel-mode ):
>
>mov $i, %eax
>int $0x82
>ret
>
>Why not invoked the hypercall directly by "int $0x82" ? What's the
>advantage of using hypercall_page?
>

This allows guest migrated to a newer/older xen with a different
hypercall invocation convention. Xen fills hypercall page by its
convention, and thus release guest from hardcoding specific flow.

Thanks
Kevin

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