[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] Why using hypercall_page ?
To invoke hypercall: 1. Not using hypercall_page: mov $__HYPERCALL_sched_op, %eax int $0x82 2. Using hypercall_page: call hypercall_page + __HYPERCALL_sched_op * 32 Besides, using the hypercall_page, guest has to keep a page for hypercall_page. I do not think the hypercall_page makes the thing much easier. Is "release guest from hardcoding" the only advantage of using hypercall_page? Thanks, Wu å 2008-10-23åç 09:24 +0800ïTian, Kevinåéï > >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 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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