Boot Configuration and eMMC Setup for Device Recovery [Guide]

Boot Configuration and eMMC Setup for Device Recovery

Configuring the boot settings on an eMMC chip is a critical first step in restoring or initializing a device. This involves modifying three key extCSD registers:

1. Boot Partition [179]: Specifies which eMMC partition is used for boot operations.
2. Bus Config [177]: Defines the width and boot mode settings.
3. H/W Reset Function [162]: Controls the reset functionality of the eMMC.

For example:

• Boot configuration: PARTITION_CONFIG: 0x00 (No boot partition configured).
• Boot bus config [177]: 0x00 (1-bit width).
• H/W reset function [RST_N_FUNCTION]: 0x01.

These registers can be set using one of four methods:

1. From a previously saved extCSD file from the same device.
2. From an extCSD file saved during eMMC firmware updates.
3. Using predefined options.
4. Manual configuration.

Writing Boot Configurations

Using tools like Repair ExtCSD -> Only Boot Config, the following values can be written:

• Boot config: 0x48, 0x00, 0x01 for registers 179, 177, and 162, respectively.

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Platform-Specific Configuration Instructions

1. MediaTek (MTK)

• Boot Config: 0x48, 0x00, 0x01
• Ensure ROM2/3/RPMB sizes are ≤2MB for MT6589/8389 processors.
• Options:
  • Write Boot Config and erase eMMC (device detected as MTK USB Port).
  • Write Boot Config and preloader to ROM2/3 (device detected as MTK Virtual VCOM Port).
  • Use backups for ROM2/3 and restore via "eMMC General."

In most cases, MTK devices can be flashed using the MTK FlashTool.

2. Intel

• Boot Config: 0x00, 0x00, 0x0x or 0x00, 0x06, 0x01.
• Steps:
  • Create a GP1 partition if required.
  • Write Boot Config, erase eMMC, and use xFSTK utility to flash the bootloader.

Devices booting into DroidBoot can be further flashed via firmware.

3. Qualcomm

• Boot Config: 0x00, 0x00, 0x0x or 0x38, 0x00, 0x01.
• Options:
  • Write Boot Config, erase eMMC (detected as HS QD9008 Loader).
  • Use "Write by Vendor" to flash bootloaders and firmware sections.

Devices can then boot into FastBoot or Recovery for complete firmware restoration.

4. Exynos

• Boot Config: 0x48, 0x01, 0x0x.
• Options:
  • Erase eMMC and use a prepared SD card for recovery.
  • Flash parts of the firmware for FastBoot or Recovery access.

5. HiSilicon

• Boot Config: 0x08, 0x02, 0x01.
• Options:
  • Write Boot Config and firmware sections for FastBoot/Recovery.
  • Write ROM2 and parts of ROM1 dump (100-500MB).

6. SpreadTrum

• Boot Config: 0x08, 0x00, 0x0x.
• Options:
  • Flash firmware via "Write by Vendor - SpreadTrum."
  • Use ROM2/3 dumps and parts of ROM1 for recovery.

7. Broadcom

• Boot Config: 0x00, 0x00, 0x0x.
• Options:
• Write Boot Config and firmware for FastBoot/Recovery.
• Flash ROM2 and part of ROM1 dump (100-500MB).