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

Vivek Goyal
2013-11-11T16:52:46Z

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.

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.

Thanks
Vivek