diff options
| author | Ingo Molnar <mingo@elte.hu> | 2009-01-31 03:57:12 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-02-05 22:27:55 +0100 |
| commit | fdbecd9fd14198853bec4cbae8bc7af93f2e3de3 (patch) | |
| tree | 7b697ba90a48fa94529e03ec7e1109864f031cf2 | |
| parent | 65a4e574d2382d83f71b30ea92f86d2e40a6ef8d (diff) | |
x86, apic: explain the purpose of max_physical_apicid
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/apic.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/arch/x86/kernel/apic.c b/arch/x86/kernel/apic.c index a04a73a51d2..5475e1c3180 100644 --- a/arch/x86/kernel/apic.c +++ b/arch/x86/kernel/apic.c @@ -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; /* |