Re: [Xen-devel] [PATCH v6 05/11] x86/hyperv: setup hypercall page

["Durrant, Paul" <pdurrant@xxxxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: 03 February 2020 11:34
> To: Durrant, Paul <pdurrant@xxxxxxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>; Xen Development List <xen-
> devel@xxxxxxxxxxxxxxxxxxxx>; Michael Kelley <mikelley@xxxxxxxxxxxxx>; Wei
> Liu <liuwe@xxxxxxxxxxxxx>; Andrew Cooper <andrew.cooper3@xxxxxxxxxx>;
> Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Subject: Re: [PATCH v6 05/11] x86/hyperv: setup hypercall page
> 
> On 03.02.2020 12:21, Durrant, Paul wrote:
> >> -----Original Message-----
> >> From: Jan Beulich <jbeulich@xxxxxxxx>
> >> Sent: 03 February 2020 11:06
> >> To: Durrant, Paul <pdurrant@xxxxxxxxxxxx>
> >> Cc: Wei Liu <wl@xxxxxxx>; Xen Development List <xen-
> >> devel@xxxxxxxxxxxxxxxxxxxx>; Michael Kelley <mikelley@xxxxxxxxxxxxx>;
> Wei
> >> Liu <liuwe@xxxxxxxxxxxxx>; Andrew Cooper <andrew.cooper3@xxxxxxxxxx>;
> >> Roger Pau Monné <roger.pau@xxxxxxxxxx>
> >> Subject: Re: [PATCH v6 05/11] x86/hyperv: setup hypercall page
> >>
> >> On 03.02.2020 11:39, Durrant, Paul wrote:
> >>>> -----Original Message-----
> >>>> From: Wei Liu <wl@xxxxxxx>
> >>>> Sent: 31 January 2020 17:57
> >>>> To: Xen Development List <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> >>>> Cc: Durrant, Paul <pdurrant@xxxxxxxxxxxx>; Michael Kelley
> >>>> <mikelley@xxxxxxxxxxxxx>; Wei Liu <liuwe@xxxxxxxxxxxxx>; Wei Liu
> >>>> <wl@xxxxxxx>; Jan Beulich <jbeulich@xxxxxxxx>; Andrew Cooper
> >>>> <andrew.cooper3@xxxxxxxxxx>; Roger Pau Monné <roger.pau@xxxxxxxxxx>
> >>>> Subject: Re: [PATCH v6 05/11] x86/hyperv: setup hypercall page
> >>>>
> >>>> (Note to self)
> >>>>
> >>>> On Fri, Jan 31, 2020 at 05:49:24PM +0000, Wei Liu wrote:
> >>>> [...]
> >>>>> +static uint64_t generate_guest_id(void)
> >>>>> +{
> >>>>> +    union hv_guest_os_id id;
> >>>>> +
> >>>>
> >>>>        id.raw = 0;
> >>>
> >>> Or just use a C99 initializer to set things up. A bit neater IMO.
> >>
> >> If you mean this for ...
> >>
> >>>>> +    id.vendor = HV_XEN_VENDOR_ID;
> >>>>> +    id.major = xen_major_version();
> >>>>> +    id.minor = xen_minor_version();
> >>
> >> ... these three fields, then this won't work with rather old gcc
> >> we still permit to be used. Using { .raw = 0 } would work afaict.
> >>
> >
> > Not even { .vendor = HV_XEN_VENDOR_ID } ?
> 
> No, because of it being part of an unnamed (struct) member of
> the union.

Ok... shame. Presumably an empty initializer - {} -  would be ok?

  Paul

> 
> Jan
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