arm64: topology: Enable ACPI/PPTT based CPU topology.
Propagate the topology information from the PPTT tree to the cpu_topology array. We can get the thread id, core_id and cluster_id by assuming certain levels of the PPTT tree correspond to those concepts. The package_id is flagged in the tree and can be found by passing an arbitrary large level to setup_acpi_cpu_topology() which terminates its search when it finds an ACPI node flagged as the physical package. If the tree doesn't contain enough levels to represent all of thread/core/cod/package then the package id will be used for the missing levels. Since server/ACPI machines are more likely to be multisocket and NUMA, this patch also modifies the default clusters=sockets behavior for ACPI machines to sockets=sockets. DT machines continue to represent sockets as clusters. For ACPI machines, this results in a more normalized view of the topology. Cluster level scheduler decisions are still being made due to the "MC" level in the scheduler which has knowledge of cache sharing domains. This code is loosely based on a combination of code from: Xiongfeng Wang <firstname.lastname@example.org> John Garry <email@example.com> Jeffrey Hugo <firstname.lastname@example.org> Signed-off-by: Jeremy Linton <email@example.com>
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