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Diffstat (limited to 'arch/x86_64/kernel/genapic.c')
-rw-r--r--arch/x86_64/kernel/genapic.c33
1 files changed, 24 insertions, 9 deletions
diff --git a/arch/x86_64/kernel/genapic.c b/arch/x86_64/kernel/genapic.c
index 69b9c25a8fc..30c843a5efd 100644
--- a/arch/x86_64/kernel/genapic.c
+++ b/arch/x86_64/kernel/genapic.c
@@ -31,6 +31,7 @@ u8 x86_cpu_to_log_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
extern struct genapic apic_cluster;
extern struct genapic apic_flat;
+extern struct genapic apic_physflat;
struct genapic *genapic = &apic_flat;
@@ -44,12 +45,7 @@ void __init clustered_apic_check(void)
u8 clusters, max_cluster;
u8 id;
u8 cluster_cnt[NUM_APIC_CLUSTERS];
-
- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
- /* AMD always uses flat mode right now */
- genapic = &apic_flat;
- goto print;
- }
+ int num_cpus = 0;
#if defined(CONFIG_ACPI_BUS)
/*
@@ -64,15 +60,34 @@ void __init clustered_apic_check(void)
#endif
memset(cluster_cnt, 0, sizeof(cluster_cnt));
-
for (i = 0; i < NR_CPUS; i++) {
id = bios_cpu_apicid[i];
- if (id != BAD_APICID)
- cluster_cnt[APIC_CLUSTERID(id)]++;
+ if (id == BAD_APICID)
+ continue;
+ num_cpus++;
+ cluster_cnt[APIC_CLUSTERID(id)]++;
}
+ /* Don't use clustered mode on AMD platforms. */
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ genapic = &apic_physflat;
+#ifndef CONFIG_CPU_HOTPLUG
+ /* In the CPU hotplug case we cannot use broadcast mode
+ because that opens a race when a CPU is removed.
+ Stay at physflat mode in this case.
+ It is bad to do this unconditionally though. Once
+ we have ACPI platform support for CPU hotplug
+ we should detect hotplug capablity from ACPI tables and
+ only do this when really needed. -AK */
+ if (num_cpus <= 8)
+ genapic = &apic_flat;
+#endif
+ goto print;
+ }
+
clusters = 0;
max_cluster = 0;
+
for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
if (cluster_cnt[i] > 0) {
++clusters;