3.5.1.14. boot_cpu_init

void __init boot_cpu_init(void)
{
    //获得boot cpu的ID
    int cpu = smp_processor_id();

    //将其在系统维护的多个位图中置位，其中包括online, active, present, possible
    set_cpu_online(cpu, true);
    set_cpu_active(cpu, true);
    set_cpu_present(cpu, true);
    set_cpu_possible(cpu, true);

    #ifdef CONFIG_SMP
    __boot_cpu_id = cpu;
    #endif
}

boot_cpu_init 用于初始化Boot CPU

3.5.1.15. build_mem_type_table

static void __init build_mem_type_table(void)
{
    struct cachepolicy *cp;
    unsigned int cr = get_cr();
    pteval_t user_pgprot, kern_pgprot, vecs_pgprot;
    pteval_t hyp_device_pgprot, s2_pgprot, s2_device_pgprot;
    int cpu_arch = cpu_architecture();
    int i;

    if(is_smp()) {
        if(cachepolicy != CPOLICY_WRITEALLOC)
            cachepolicy = CPOLICY_WRITEALLOC;
        if(!(initial_pmd_value & PMD_SECT_S))
            initial_pmd_value |= PMD_SECT_S;
    }

    if(cpu_is_xsc3() || (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP))) {
        if(!cpu_is_xsc3()) {
            //对各个成员的prot_sect标志增加PMD_SECT_XN支持
            //XN为Execute-Never,即指明处理器能否在该区域上执行程序
            mem_types[MT_DEVICE].prot_sect |= PMD_SECT_XN;
            mem_types[MT_DEVICE_NONSHARED].pro_sect |= PMD_SECT_XN;
            mem_types[MT_DEVICE_CACHED].pro_sect |= PMD_SECT_XN;
            mem_types[MT_DEVICE_WC].pro_sect |= PMD_SECT_XN;

            mem_types[MT_MEMORY_RW].prot_sect |= PMD_SECT_XN;
        }

        if(cpu_arch >= CPU_ARCH_ARMv7 && (cr & CR_TRE)) {
            mem_types[MT_DEVICE].prot_sect |= PMD_SECT_TEX(1);
            mem_types[MT_DEVICE_NONSHARED].prot_sect |= PMD_SECT_TE(1);
            mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_BUFFERABLE;
        }
    }

    cp = &cache_policies(cachepolicy);
    vecs_pgprot = kern_pgprot = user_pgprot = cp->pte;
    s2_pgprot = cp->pte_s2;
    hyp_device_pgprot = mem_types[MT_DEVICE].prot_pte;
    s2_device_pgprot = mem_types[MT_DEVICE].prot_pte_s2;
}

注解

TRE位用于SCTLR寄存器的bit28, 用于页表TEX remap使能．如果该位置位，那么在页表中，TEX[2:1]被分配给操作系统管理，而TEX[0], C, B位以及MMU remap寄存器用于描述内存区的属性．反之如果该位清零，那么页表中，TEX[2:0]和C, B位一起用于描述内存区域的属性

警告

此函数待完善………