Re: [PATCH v4 1/3] x86, apic: Don't count the CPU with BP flag fromMP table as booting-up CPU

[HATAYAMA Daisuke]

(2013/11/12 9:40), HATAYAMA Daisuke wrote:
> (2013/11/12 1:52), Vivek Goyal wrote:
> > On Mon, Nov 11, 2013 at 11:52:30AM +0900, HATAYAMA Daisuke wrote:
> >
> > [..]
> > > Looking at my past investigation, kernel/mpparse.c, mm/amdtopology.c and
> > > platform/visws/visws_quirks.c assumes that boot_cpu_physical_apicid
> > > has initial apicid of the BSP, not the current actual booting-up cpu.
> > >
> > > These three are called in get_smp_config() below. If either of them is
> > > called actually, boot_cpu_physical_apicid has the apicid different from
> > > the current actual booting-up cpu temporarily. But init_apic_mappings()
> > > soon modifies back the value to the one obtained by read_apic_id().
> > >
> > >          /*
> > >           * Read APIC and some other early information from ACPI tables.
> > >           */
> > >          acpi_boot_init();
> > >          sfi_init();
> > >          x86_dtb_init();
> > >
> > >          /*
> > >           * get boot-time SMP configuration:
> > >           */
> > >          if (smp_found_config)
> > >                  get_smp_config();
> > >
> > >          prefill_possible_map();
> > >
> > >          init_cpu_to_node();
> > >
> > >          init_apic_mappings();
> > >
> > > So, thanks to init_apic_mappings(), the patch set would work without the
> > > first patch... This is a careless point in this patch set.
> >
> > If init_apic_mappings(), is making sure that boot_cpu_physical_apicid is
> > apic id of booting processor, and you don't need first patch of your
> > series, then I think atleast re-post your patch series without first
> > patch.
>
> Yes, I'll repost soon.
>
> > And then there can be another series which looks into whether we need
> > two different variables or not and if we do, then a separate variable
> > bsp_physical_apicid will track the bsp id as reported by BIOS and
> > boot_cpu_physical_apicid will track apic id of booting cpu. This might
> > a very big and slow cleanup. So I think blocking the first patch series
> > behind it might not make much sense.
>
> Yes, the current handling of boot_cpu_physical_apicid looks strange and
> should be cleaned up, but the cleaning up needs reviewing together with
> the maintainers for the corresponding part; in particular, it can be
> lengthy for the reviewing on amdtopology.c. I leave this as another
> work for the time being.

Sorry for my confusion. It's necessary to introduce a new variable to keep
the initial APIC ID for the processor with BSP flag on IA32_APIC_BASE MSR,
which is needed in case of AP is specified by disable_cpu_apicid and using
MP table.

I've posted new v5 patch set a little ago. Could you please review it?

--
Thanks.
HATAYAMA, Daisuke

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