An operating system is necessary in most applications to manage hardware and software resources, while the released kernel carries rich features or low-level drivers that may not fit the user's hardware. For this reference design, run the fit kernel on board by applying a patch to processor SDK. Figure 3-2 shows the instructions used for this process.
Figure 3-2 How to Apply a Patch to the Processor SDK
Comparing to the AM335x EVM or Beagle Bone family, the differences in hardware are:
- The EEPROM on this board does not contain the information of board ID.
- This board does not support the internal RTC.
- This board does not support the PMIC IC for power management.
The brief principle of modified codes behind the patch files:
- U-Boot: Disable the board detect function and enforce the return value for "am335x-boneblack".
- U-Boot: Disable the I2C communication with PMIC.
- U-Boot: Disable the RTC related function.
- U-Boot: Disable the "BOOTCOUNT_LIMIT" configuration during auto booting.
- Kernel: Remove the RTC node, PMIC node and related codes in device tree (DTS file).
- Kernel: Disable the "RTC Real Time Clocking" configuration.
- Kernel: Add WL1837MOD driver configuration.