# APSS 冷启动流

冷启动是指从断电状态启动系统。这些步骤仅从 PBL 开始。

冷启动流程如下图所示。

![../../_images/boot-arch.png](data:image/png;base64,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)

**图：冷启动流程**

冷启动过程在两种安全模式下运行：安全模式和非安全模式。在 EL0、EL1 和 EL2 [异常级别](https://developer.arm.com/documentation/102412/0103/Privilege-and-Exception-levels/Exception-levels)，启动内核可以在安全或非安全模式下运行，但在 EL3 上它始终在安全模式下运行。Linux内核在 nonsecure EL1 状态下运行。在安全 EL3 状态下完成安全设置后，XBL 可以切换至 UEFI 非安全 EL1 状态。

有关安全模式的详细信息，请参见[软件安全架构](https://docs.qualcomm.com/bundle/publicresource/topics/80-70018-11/architecture.html)。

冷启动序列涉及以下步骤：

1. 重置后，boot core退出重置状态并执行PBL。PBL 初始化硬件时钟、CPU 缓存、内存管理单元 (MMU)，并根据启动选项设置识别启动设备
2. PBL 从启动设备加载并验证 XBL。XBL 在 EL3 安全状态下运行安全设置并执行以下任务：

    1. 初始化硬件、固件镜像、CPU 缓存、MMU、启动设备、PMIC 和 DDR。
    2. 从启动设备加载 Qualcomm TEE 镜像并进行鉴权。
    3. 加载并验证 Qualcomm Hypervisor 镜像。
    4. 加载并验证 UEFI 镜像。
    5. 执行 secure channel manager (SCM) 调用以跳转到 Qualcomm TEE 镜像。SCM 是使用[安全监视器调用](https://developer.arm.com/documentation/ddi0333/latest/programmer-s-model/exceptions/secure-monitor-call--smc-) (SMC) 与 Qualcomm TEE 进行通信的驱动程序。
3. Qualcomm TEE 设置安全环境并运行 Qualcomm Hypervisor 镜像。
4. Qualcomm Hypervisor 将控制权移交给 UEFI，然后 UEFI 使用 [UEFI 安全启动](https://docs.qualcomm.com/bundle/publicresource/topics/80-70018-11/enable-uefi-secure-boot.html)加载并验证 systemd 启动 EFI 镜像。
5. systemd-boot 镜像加载并验证 Qualcomm Linux 内核镜像，然后将控制权传递给 Qualcomm Linux 内核。如果启用基于内核的虚拟机 (KVM) 模式，UEFI 会关闭 Qualcomm Hypervisor，退出 UEFI 启动服务，并将控制权传递给 EL2 中的 Linux KVM。
6. Qualcomm Linux 内核启动 bash shell 等 Linux 应用程序。

有关更多的独立且平行于APSS启动流的实时子系统冷启动流 (RTSS) , 请参阅 [RTSS cold boot flow](https://docs.qualcomm.com/doc/80-70018-4SC/topic/RTSS_Cold_Boot_Flow.html#sail).

Last Published: May 13, 2025

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