Re: [PATCH v8 01/13] x86/apic: Construct a selector for the interrupt delivery mode

[Dou Liyang]

Hi Baoquan,

At 09/13/2017 10:30 AM, Baoquan He wrote:
> Hi dou,
>
> On 09/12/17 at 09:20am, Dou Liyang wrote:
> > I thought again and again, I would not change this check logic.
> >
> > Because actually, we have three possibilities:
> >
> >   1. ACPI on chip
> >   2. 82489DX
> >   3. no APIC
> >
> > lapic_is_integrated() is used to check the APIC's type which is
> > APIC on chip or 82489DX. It has a prerequisite, we should avoid
> > the third possibility(no APIC) first, which is decided by
> > boot_cpu_has(X86_FEATURE_APIC) and smp_found_config. So, the original
> > logic:
> >
> > if (!boot_cpu_has(X86_FEATURE_APIC) && !smp_found_config)
>
> I won't insist that the logic need be changed. From the test result, the
> patchset works very well with notsc specified. And the whole patchset
> looks not risky. Maybe the patch putting acpi_early_init() earlier can
> be posted independently and involve other ARCHes maintainer to review.

Yes,  I will send it as an independent patch, and Cc other ARCH
maintainers

> About the code logic, I think the confusion comes from the unclear
> condition check. E.g the above case, you said it's used to check
> discrete apic, in fact !boot_cpu_has(X86_FEATURE_APIC) could means 3
> cases:
> 1) discrete apic
> 2) no apic
> 3) integrated apic but disabled by bios.

Indeed

> See, that's why it's confusing, the condition of judgement is not
> adequate. I don't know why the code contributer wanted to check discrete
> apic case with it.
>
> Anyway, after discussion, it's clear to me now. And the code works well.
> So it's up to you to change it or not. Except of this place, the whole
> patchset looks good.

Thank you very much for your review and test.


Thanks,
	dou.
> Thanks
> Baoquan
>
> > ...is not just for 82489DX, but also for no APIC.
> >
> > It looks more correct and understandable than us.
> >
> > I am sorry my comments were wrong, and misled us. I will modify it
> > in my next version.
> >
> > BTW, How about your test result, is this series OK?
> >
> > Thanks,
> > 	dou.