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x86, apic: explain the purpose of max_physical_apicid
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Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Ingo Molnar committed Feb 5, 2009
1 parent 65a4e57 commit fdbecd9
Showing 1 changed file with 15 additions and 2 deletions.
17 changes: 15 additions & 2 deletions arch/x86/kernel/apic.c
Original file line number Diff line number Diff line change
Expand Up @@ -50,13 +50,26 @@
#include <asm/smp.h>

unsigned int num_processors;

unsigned disabled_cpus __cpuinitdata;

/* Processor that is doing the boot up */
unsigned int boot_cpu_physical_apicid = -1U;
EXPORT_SYMBOL(boot_cpu_physical_apicid);

/*
* The highest APIC ID seen during enumeration.
*
* This determines the messaging protocol we can use: if all APIC IDs
* are in the 0 ... 7 range, then we can use logical addressing which
* has some performance advantages (better broadcasting).
*
* If there's an APIC ID above 8, we use physical addressing.
*/
unsigned int max_physical_apicid;

/* Bitmask of physically existing CPUs */
/*
* Bitmask of physically existing CPUs:
*/
physid_mask_t phys_cpu_present_map;

/*
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