From: Changbin Du Date: Wed, 8 May 2019 15:21:40 +0000 (+0800) Subject: Documentation: x86: convert x86_64/cpu-hotplug-spec to reST X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=bdde117ffed2625389787f82fc92724b486ce976;p=linux.git Documentation: x86: convert x86_64/cpu-hotplug-spec to reST This converts the plain text documentation to reStructuredText format and add it to Sphinx TOC tree. No essential content change. Signed-off-by: Changbin Du Reviewed-by: Mauro Carvalho Chehab Signed-off-by: Jonathan Corbet --- diff --git a/Documentation/x86/x86_64/cpu-hotplug-spec b/Documentation/x86/x86_64/cpu-hotplug-spec deleted file mode 100644 index 3c23e0587db33..0000000000000 --- 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. diff --git a/Documentation/x86/x86_64/cpu-hotplug-spec.rst b/Documentation/x86/x86_64/cpu-hotplug-spec.rst new file mode 100644 index 0000000000000..8d1c91f0c8800 --- /dev/null +++ b/Documentation/x86/x86_64/cpu-hotplug-spec.rst @@ -0,0 +1,24 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=================================================== +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. diff --git a/Documentation/x86/x86_64/index.rst b/Documentation/x86/x86_64/index.rst index e2a324cde6710..c04b6eab3c764 100644 --- a/Documentation/x86/x86_64/index.rst +++ b/Documentation/x86/x86_64/index.rst @@ -12,3 +12,4 @@ x86_64 Support mm 5level-paging fake-numa-for-cpusets + cpu-hotplug-spec