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Diffstat (limited to 'Documentation/x86/x86_64/cpu-hotplug-spec')
| -rw-r--r-- | Documentation/x86/x86_64/cpu-hotplug-spec | 21 |
1 files changed, 0 insertions, 21 deletions
diff --git a/Documentation/x86/x86_64/cpu-hotplug-spec b/Documentation/x86/x86_64/cpu-hotplug-spec deleted file mode 100644 index 3c23e0587db3..000000000000 --- a/Documentation/x86/x86_64/cpu-hotplug-spec +++ /dev/null @@ -1,21 +0,0 @@ -Firmware support for CPU hotplug under Linux/x86-64 ---------------------------------------------------- - -Linux/x86-64 supports CPU hotplug now. For various reasons Linux wants to -know in advance of boot time the maximum number of CPUs that could be plugged -into the system. ACPI 3.0 currently has no official way to supply -this information from the firmware to the operating system. - -In ACPI each CPU needs an LAPIC object in the MADT table (5.2.11.5 in the -ACPI 3.0 specification). ACPI already has the concept of disabled LAPIC -objects by setting the Enabled bit in the LAPIC object to zero. - -For CPU hotplug Linux/x86-64 expects now that any possible future hotpluggable -CPU is already available in the MADT. If the CPU is not available yet -it should have its LAPIC Enabled bit set to 0. Linux will use the number -of disabled LAPICs to compute the maximum number of future CPUs. - -In the worst case the user can overwrite this choice using a command line -option (additional_cpus=...), but it is recommended to supply the correct -number (or a reasonable approximation of it, with erring towards more not less) -in the MADT to avoid manual configuration. |