问题描述
5.4 HiFive Unleashed Boot
The Freedom U500 supports several boot methods. The general flow follows multiple stages:
1. ROM0 (0x1004): Decode MSEL and jump to the address found in 0x1100 + 8*MSEL. For
MSEL > 4, the process proceeds to the next step.
2. ROM1 (0x1_0000): Decode MSEL to determine which media contains the First Stage Boot
Loader (FSBL). The media is expected to be formatted with a GPT partition table (even on
SPI flash). The entire contents of the first partition with GUID type
5B193300-FC78-40CD-8002-E86C45580B47 are downloaded into the L2 sideband memory
and execution transfers there. ROM1 contains a hard-coded DTB block passed in a1 to the
FSBL, which ignores it.
3. FSBL (0x800_0000): Initialize core PPLs, DDR, and Ethernet PHY. Decode MSEL to deter-
mine which media contains the Berkeley Boot Loader (BBL). The media is expected to con-
tain a GPT-formatted partition table. The contents of the first partition with GUID type
2E54B353-1271-4842-806F-E436D6AF6985 are downloaded into DDR memory and exe-
cution transfers there. The FSBL contains an embedded DTB describing both the Freedom
U500 SoC and HiFive Unleashed board. The DTB is updated with the board MAC address
and DDR capacity and passed to BBL in a1.
4. BBL (0x8000_0000): Initialize the RISC-V supervisor binary interface (SBI). Jump to the
embedded linux kernel payload, passing a redacted DTB in a1.
5. Linux (0xffff_ffe0_0000_0000): Initializes all devices, starts DHCP + ssh.
零阶段启动加载程序（ZSBL），它包含在片上掩码 ROM 中，并由 QEMU 提供。请注意，QEMU 实现的 ROM 代码与硬件中编程的代码并不相同。QEMU 的版本是一个简化版，但提供了与硬件相同的功能。
一阶段启动加载程序（FSBL），它负责启动 PLL 和 DDR 内存。这是一部分 U-Boot SPL。
二阶段启动加载程序（SSBL），它根据需要进一步初始化其他外设。这是一部分完整的 U-Boot，结合了一个 OpenSBI fw_dynamic 固件镜像。
这个是SiFive HiFive Unleashed (sifive_u)的启动过程，k230这边是怎么样的？
也是和sifive一样，要求BOOT0，BOOT1选中的目标设备上有gpt分区？
那他把目标分区的数据(FSBL)加载到了哪里？
