Re: [Xen-devel] [RFC PATCH] xen_cpufreq implementation in kernel

[Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>]

On Tue, Oct 7, 2014 at 6:44 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> On 10/07/2014 03:20 PM, Oleksandr Dmytryshyn wrote:
>> Hi to all.
>
> Hi Oleksandr,
>
>> Next series of patches implements xen-cpufreq driver in kernel.
>>
>> Cpufreq core and registered cpufreq governors are located in xen. Dom0 has 
>> CPU
>> driver which can only change frequency of the physical CPUs. In addition this
>> driver can change CPUs regulator voltage. At start time xen-cpufreq driver
>> in kernel uploads to Xen information about physical cpus.
>> Xen notifies Dom0 kernel using VIRQ_CPUFREQ interrupt. Then xen-cpufreq 
>> driver
>> in kernel uses XEN_SYSCTL_cpufreq_op operation from HYPERVISOR_sysctl 
>> hypercall
>> to get some parameters from Xen (frequency, relation and cpu number).
>> Then xen-cpufreq changes frequency on physical cpu and uses the same
>> XEN_SYSCTL_cpufreq_op operation ti give the result to Xen.
>>
>> Next configs should be enabled to use xen-cpufreq driver:
>> CONFIG_GENERIC_CPUFREQ_CPU0
>> CONFIG_XEN_CPUFREQ
>
> It's common to CC maintainers of the specific code in each patch. You
> only CC Xen folks, but some parts of the code touch the cpufreq
> subsystem. I believe that those guys will have the last word on those
> changes.
I'll CC Kernel folks in the next patch-set.

> Regards,
>
> --
> Julien Grall

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