Re: [Xen-devel] [PATCH 08/17 v5] xen/arm: vpl011: Add a new domctl API to initialize vpl011

[Bhupinder Thakur <bhupinder.thakur@xxxxxxxxxx>]

Hi Julien,

>>>> +#if defined (__arm__) || defined(__aarch64__)
>>>> +/**
>>>> + * This function initializes the vpl011 emulation and returns
>>>> + * the event to be used by the backend for communicating with
>>>> + * the emulation code.
>>>> + *
>>>> + * @parm xch a handle to an open hypervisor interface
>>>> + * @parm domid the domain to get information from
>>>> + * @parm console_domid the domid of the backend console
>>>> + * @parm gfn the guest pfn to be used as the ring buffer
>>>> + * @parm evtchn the event channel to be used for events
>>>> + * @return 0 on success, negative error on failure
>>>> + */
>>>> +int xc_dom_vpl011_init(xc_interface *xch,
>>>> +                       uint32_t domid,
>>>> +                       uint32_t console_domid,
>>>> +                       xen_pfn_t gfn,
>>>> +                       evtchn_port_t *evtchn);
>>>> +#endif
>>>
>>>
>>> Actually, the pattern is to define the xc_ function on all architecture
>>> but only return ENOSYS where it's not implemented, see
>>> xc_vcpu_get_extstate.
>>
>>
>> Well, I think the main reason behind if to avoid dummy call to the
>> hypervisor. But effectively the hypervisor will return a proper error.
>
>
> Actually, looking at the public header. This is because vcpu_get_extstate
> structure is only available on x86. Whereas vpl011_init is available for all
> the architecture even though only ARM effectively implementing it.
>
> But my point stands below, there is no harm to implement it for x86 as it
> would compile on any platform.
>
>
>>
>> As the call is not made in common code, I would make this function
>> compile on all the platform (there are nothing arch specific in it).

Currently, xc_dom_vpl011_init() is called only if info->arch_arm.vuart
flag is true. This check may look a bit odd in the
common code.

Regards,
Bhupinder

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