Messages in this thread | | | Subject | Re: Is this code chunk in init_apic_mappings() superfluous? | From | Cao jin <> | Date | Wed, 11 Mar 2020 20:39:37 +0800 |
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On 3/7/20 7:27 PM, Thomas Gleixner wrote: > Cao jin <caoj.fnst@cn.fujitsu.com> writes: >> Hi, >> >> I am trying to figure the following code chunk out: >> >> if (x2apic_mode) { >> boot_cpu_physical_apicid = read_apic_id(); >> return; >> } >> >> As my understanding, even in x2APIC mode, boot_cpu_physical_apicid is >> also got via early_acpi_process_madt --> ... --> register_lapic_address, >> so, is it for any corner case I am not aware? > > The case when there are neither ACPI nor valid mptables. Unlikely, but > possible in theory. >
I noticed this case in its calling comments, but failed to associate it with a x2APIC...
So init_apic_mapping() is for 2 corner cases that doesn't map APIC register before: one you mentioned here, and MP default configuration the other.
Thanks Thomas.
-- Sincerely, Cao jin
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