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//  $Source: src/include/kernel/cpu.H $
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/** @file cpu.H
 *  @brief Defines kernel information and functions about CPUs.
 *
 *  In this kernel the term CPU refers to a hardware thread (SMT), not core.
 */
#ifndef __KERNEL_CPU_H
#define __KERNEL_CPU_H

#include <kernel/types.h>
#include <arch/ppc.H>
#include <builtins.h>
#include <sys/sync.h>

// Thread ID support only, Power7 (4 threads).
#define KERNEL_MAX_SUPPORTED_CPUS (4 * 8 * 4) // Sockets, cores, threads.

class Scheduler;

/** @struct cpu_t
 *  @brief Stores per-CPU kernel information.
 *
 *  @note kernel_stack and master need to be at fixed locations in this
 *        structure due to usages in start.S.
 *
 *  - kernel_stack is a double-word at cpu_t[0 bytes].
 *  - master is a byte at cpu_t[12 bytes].
 */
struct cpu_t
{
    /** Stack to use while in kernel mode. */
    void* kernel_stack;

    /** ID of the CPU (PIR value) */
    cpuid_t cpu;

    struct
    {
        /** If the CPU is the master */
        bool master;

        /** Ensure alignment of master attribute for asm code. */
        uint64_t __reserved_master:24;
    } PACKED;

    /** Pointer to the scheduler for this CPU (may not be unique) */
    Scheduler* scheduler;

    /** Location for scheduler to store per-CPU data, currently used
     *  for the local run-queue for processor affinity.
     */
    void* scheduler_extra;

    /** Pointer to the idle task for this CPU */
    task_t* idle_task;

    /** XSCOM mutex to serialize access per CPU */
    mutex_t xscom_mutex;
};

/** @fn getCpuId
 *  @brief Read the PIR value to determine the cpuid_t of this CPU.
 */
ALWAYS_INLINE
inline cpuid_t getCpuId()
{
    return getPIR() & (KERNEL_MAX_SUPPORTED_CPUS - 1);
}

#endif