Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) .. SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3) ===================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4) Firmware support for CPU hotplug under Linux/x86-64
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5) ===================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7) Linux/x86-64 supports CPU hotplug now. For various reasons Linux wants to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8) know in advance of boot time the maximum number of CPUs that could be plugged
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9) into the system. ACPI 3.0 currently has no official way to supply
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) this information from the firmware to the operating system.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) In ACPI each CPU needs an LAPIC object in the MADT table (5.2.11.5 in the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) ACPI 3.0 specification).  ACPI already has the concept of disabled LAPIC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) objects by setting the Enabled bit in the LAPIC object to zero.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) For CPU hotplug Linux/x86-64 expects now that any possible future hotpluggable
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) CPU is already available in the MADT. If the CPU is not available yet
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) it should have its LAPIC Enabled bit set to 0. Linux will use the number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) of disabled LAPICs to compute the maximum number of future CPUs.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) In the worst case the user can overwrite this choice using a command line
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) option (additional_cpus=...), but it is recommended to supply the correct
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) number (or a reasonable approximation of it, with erring towards more not less)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) in the MADT to avoid manual configuration.