Lines Matching +full:system +full:- +full:firmware

1 .. SPDX-License-Identifier: GPL-2.0
9 CPUs online/offline using PSCI. This document is about ACPI firmware allowing
10 CPUs that were not available during boot to be added to the system later.
15 CPU Hotplug on physical systems - CPUs not present at boot
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20 in one of the sockets can be replaced while the system is running.
24 In the arm64 world CPUs are not a single device but a slice of the system.
26 while the system is running, and ACPI is not able to sufficiently describe
31 not discoverable, and must be described by firmware.
34 boot to discover the system wide supported features. ACPI's MADT GICC
42 CPU Hotplug on virtual systems - CPUs not enabled at boot
43 ---------------------------------------------------------
45 Virtual systems have the advantage that all the properties the system will
46 ever have can be described at boot. There are no power-domain considerations
51 marked as disabled by firmware. Only the CPU's online/offline behaviour is
52 influenced by firmware. An example is where a virtual machine boots with a
56 For a virtual machine, the VMM (e.g. Qemu) plays the part of firmware.
58 Virtual hotplug is implemented as a firmware policy affecting which CPUs can be
59 brought online. Firmware can enforce its policy via PSCI's return codes. e.g.
63 that firmware wishes to disable either from boot (or later) should not be
71 must always report the CPU as ``present``. Changes to the firmware policy can
72 be notified to the OS via device-check or eject-request.
75 modified dynamically by firmware. Soft-restart features such as kexec will
76 re-read the static properties of the system from these static tables, and
77 may malfunction if these no longer describe the running system. Linux will
78 re-discover the dynamic properties of the system from the _STA method later