Re: [Xen-devel] [PATCH RFC V4 5/5] Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock

[Avi Kivity <avi@xxxxxxxxxx>]

On 01/14/2012 08:27 PM, Raghavendra K T wrote:
> +
> +5. KVM_HC_KICK_CPU
> +------------------------
> +value: 5
> +Architecture: x86
> +Purpose: Hypercall used to wakeup a vcpu from HLT state
> +
> +Usage example : A vcpu of a paravirtualized guest that is busywaiting in 
> guest
> +kernel mode for an event to occur (ex: a spinlock to become available)
> +can execute HLT instruction once it has busy-waited for more than a
> +threshold time-interval. Execution of HLT instruction would cause
> +the hypervisor to put the vcpu to sleep (unless yield_on_hlt=0) until 
> occurence
> +of an appropriate event. Another vcpu of the same guest can wakeup the 
> sleeping
> +vcpu by issuing KVM_HC_KICK_CPU hypercall, specifying APIC ID of the vcpu to 
> be
> +wokenup.

Wait, what happens with yield_on_hlt=0?  Will the hypercall work as
advertised?

> +
> +TODO:
> +1. more information on input and output needed?
> +2. Add more detail to purpose of hypercalls.
>


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


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