Difference between revisions of "Hypercall"
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A hypercall is to a syscall what a [[hypervisor]] is to an OS. Alternatively, a hypercall is to a hypervisor what a syscall is to a kernel. A hypercall is a software trap from a [[domain]] to the hypervisor, just as a syscall is a software trap from an application to the kernel. Domains will use hypercalls to request privileged operations like updating pagetables. Like a syscall, the hypercall is synchronous, but the return path from the hypervisor to the domain uses event channels. An event channel is a queue of asynchronous notifications, and notify of the same sorts of events that interrupts notify on native hardware. When a domain with pending events in its queue is scheduled, the OS's event-callback handler is called to take appropriate action. |
A hypercall is to a syscall what a [[hypervisor]] is to an OS. Alternatively, a hypercall is to a hypervisor what a syscall is to a kernel. A hypercall is a software trap from a [[domain]] to the hypervisor, just as a syscall is a software trap from an application to the kernel. Domains will use hypercalls to request privileged operations like updating pagetables. Like a syscall, the hypercall is synchronous, but the return path from the hypervisor to the domain uses event channels. An event channel is a queue of asynchronous notifications, and notify of the same sorts of events that interrupts notify on native hardware. When a domain with pending events in its queue is scheduled, the OS's event-callback handler is called to take appropriate action. |
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Revision as of 17:15, 28 November 2011
A hypercall is to a syscall what a hypervisor is to an OS. Alternatively, a hypercall is to a hypervisor what a syscall is to a kernel. A hypercall is a software trap from a domain to the hypervisor, just as a syscall is a software trap from an application to the kernel. Domains will use hypercalls to request privileged operations like updating pagetables. Like a syscall, the hypercall is synchronous, but the return path from the hypervisor to the domain uses event channels. An event channel is a queue of asynchronous notifications, and notify of the same sorts of events that interrupts notify on native hardware. When a domain with pending events in its queue is scheduled, the OS's event-callback handler is called to take appropriate action.
See xen/include/public/xen.h in the Xen sources.
