SMSM为处理状态而非数据的共享内存，主要就电源管理、共享内存、定时器、进程状态等信息在多核之间进行通信。SMSM的实现框架和SMD数据通信的实现类似。

SMSM的状态共有：SMSM_INIT、SMSM_OSENTERED、SMSM_SMDWAIT、SMSM_SMDINIT、SMSM_RPCWAIT、SMSM_RPCINIT、SMSM_RESET、SMSM_RSA、SMSM_RUN、SMSM_PWRC、SMSM_TIMEWAIT、SMSM_TIMENIT、SMSM_PWRC_ EARLY_EXIT、SMSM_WFPI、SMSM_SLEEP、SMSM_SLEEPEXIT、SMSM_OEMSBL_ RELEASE、SMSM_APPS_REBOOT、SMSM_SYSTEM_POWER_DOWN、SMSM_SYSTEM_ REBOOT、SMSM_SYSTEM_DOWNLOAD、SMSM_PWRC_SUSPEND、SMSM_APPS_ SHUTDOWN、SMSM_SMD_LOOPBACK、SMSM_RUN_QUIET、SMSM_MODEM_WAIT、SMSM_MODEM_BREAK、SMSM_MODEM_CONTINUE、SMSM_UNKNOWN等。

在实际应用上，SMSM主要在处理器发生状态变化，以及发生中断、重设基带处理器时运行，下面结合处理器状态变化和中断等两种情况简要介绍SMSM的处理过程。

处理处理器的变化，首先判断接入点的有效性，是应用处理器还是基带处理器等。如果接入点有效，就分配共享内存，并将相应的信息通知给其他的SMSM，下面是smsm_change_state()函数的实现：

代码1-1 SMSM改变状态的过程

int smsm_change_state(uint32_t smsm_entry,uint32_t clear_mask, uint32_t set_mask)
    {
        unsigned long flags;
        uint32_t *smsm;
        uint32_t old_state;
        if (smsm_entry >= SMSM_NUM_ENTRIES)
        { //判断有效性
            printk(KERN_ERR "smsm_change_state: Invalid entry %d",smsm_entry);
            return -EINVAL;
        }
        spin_lock_irqsave(&smem_lock, flags);
        smsm=smem_alloc(ID_SHARED_STATE,SMSM_NUM_ENTRIES * sizeof(uint32_t));//分配共享内存
        if (smsm) {
            old_state=smsm[smsm_entry];
            smsm[smsm_entry]=(smsm[smsm_entry] & ~clear_mask) | set_mask;
            if (msm_smd_debug_mask & MSM_SMSM_DEBUG)
            printk(KERN_INFO "smsm_change_state %x\n",smsm[smsm_entry]);
        notify_other_smsm(SMSM_APPS_STATE, old_state, smsm[smsm_entry]);
        } //通知其他SMSM
        spin_unlock_irqrestore(&smem_lock, flags);
        if (smsm==NULL) {
            printk(KERN_ERR "smsm_change_state< SM NO STATE>\n");
            return -EIO;
        }
        return 0;
    }

当INT_A9_M2A_5和INT_ADSP_A11中断发生时，会触发SMSM的中断处理函数，SMSM处理中断的过程如下：

代码1-2 SMSM处理中断的过程

static irqreturn_t smsm_irq_handler(int irq, void *data)
    {
        unsigned long flags;
        uint32_t *smsm;
        static uint32_t prev_smem_q6_apps_smsm;
        if (irq==INT_ADSP_A11) {
            smsm=smem_alloc(SMEM_SMD_SMSM_INTR_MUX,SMSM_NUM_INTR_MUX * sizeof(uint32_t));//分配内存
            if (!smsm ||
              (smsm[SMEM_Q6_APPS_SMSM]==prev_smem_q6_apps_smsm))
              return IRQ_HANDLED;
            prev_smem_q6_apps_smsm=smsm[SMEM_Q6_APPS_SMSM];
        }
        spin_lock_irqsave(&smem_lock, flags);
        smsm=smem_alloc(ID_SHARED_STATE,SMSM_NUM_ENTRIES * sizeof(uint32_t));//分配内存
        if (smsm==0) {
            printk(KERN_INFO "< SM NO STATE>\n");
        } else {
        unsigned old_apps, apps;
        unsigned modm=smsm[SMSM_MODEM_STATE];
        old_apps=apps=smsm[SMSM_APPS_STATE];
        if (msm_smd_debug_mask & MSM_SMSM_DEBUG)
          printk(KERN_INFO "< SM %08x %08x>\n", apps, modm);
        if (apps & SMSM_RESET) {
            apps &=~SMSM_RESET;
            smd_fake_irq_handler(0); //让SMD响应假中断
            modem_queue_start_reset_notify(); //发起重设提醒
        } else if (modm & SMSM_RESET) {
            apps |=SMSM_RESET;
        } else {
            apps|=SMSM_INIT;
            if (modm & SMSM_SMDINIT)
                apps|=SMSM_SMDINIT;
            if (modm & SMSM_RPCINIT)
                apps|=SMSM_RPCINIT;
            if ((apps & (SMSM_INIT|SMSM_SMDINIT|SMSM_RPCINIT))==
                (SMSM_INIT|SMSM_SMDINIT|SMSM_RPCINIT))
                apps|=SMSM_RUN;
        }
        if (smsm[SMSM_APPS_STATE]!=apps) {
            if (msm_smd_debug_mask & MSM_SMSM_DEBUG)
              printk(KERN_INFO "< SM %08x NOTIFY>\n", apps);
            smsm[SMSM_APPS_STATE]=apps;
            do_smd_probe();
            notify_other_smsm(SMSM_APPS_STATE, old_apps, apps);
            //通知其他SMSM
            }
        }
        spin_unlock_irqrestore(&smem_lock, flags);
        return IRQ_HANDLED;
    }