Re: [PATCH v4 04/14] x86/rtc: replace paravirt rtc check with platform legacy quirk

[Juergen Gross]

On 08/04/16 08:29, Luis R. Rodriguez wrote:
> On Thu, Apr 7, 2016 at 10:18 PM, Juergen Gross <jgross@xxxxxxxx> wrote:
>> On 08/04/16 02:32, Luis R. Rodriguez wrote:
>>> This highlights a semantic gap issue. From a quick cursory review, I think
>>> we can address this temporarily by just using a check:
>>>
>>> void __init x86_early_init_platform_quirks(void)
>>> {
>>>       x86_platform.legacy.rtc = 1;
>>>
>>>       switch (boot_params.hdr.hardware_subarch) {
>>>       case X86_SUBARCH_XEN:
>>>       case X86_SUBARCH_LGUEST:
>>>       case X86_SUBARCH_INTEL_MID:
>>> -             x86_platform.legacy.rtc = 0;
>>> +             if (x86_init.mpparse.get_smp_config != x86_init_uint_noop)
>>> +                     x86_platform.legacy.rtc = 0;
>>
>> No! Why don't you just use the explicit test xen_initial_domain() ?
> 
> Because we don't want to sprinkle Xen specific code outside of Xen
> code. What do you think about the second possibility I listed?
> Otherwise, any other ideas?

Don't try to guess.

In case you don't want to inject Xen internals here, just call a Xen
function to either return the correct value, or to set all structure
elements correctly.

Thinking more about it: why not do that for all the subarchs? You'd
have the specific settings where they belong: in a subarch specific
source. Just do the default settings in x86_early_init_platform_quirks()
and let the subarch functions set the non-default values.


Juergen