| |
| The bootloader environment consists of a set of libraries that provide |
| various features and a couple small driver programs that build against |
| these libraries. The libraries used come from three categories -- |
| generic (containing code useful to any bootloader), architecture |
| (containing code useful to a specific cpu, system-on-chip, etc), and |
| board (containing code useful to a single specific device) |
| |
| For the purpose of this discussion, we will involve the fictional |
| companies Outstanding Electronics Manufacturing (OEM) and Silicon |
| Engineering Management, Inc (SEMI). OEM produces the quality Brick |
| mobile device using SEMI's 65002 ARM-based system-on-chip. |
| |
| Common bootloader libraries and base architectures: |
| |
| boot/include/boot headers |
| boot/libboot libboot.a |
| boot/libc libboot_c.a |
| boot/arch_armv6 libboot_arch_armv6.a |
| |
| Architecture-specific libraries for SEMI 65002 SOC: |
| |
| partner/semi/boot/include/65002 headers |
| partner/semi/boot/arch_65002 liboot_arch_65002.a |
| |
| Device-specific library for OEM Brick phone: |
| |
| partner/oem/brick/product_config.mk configuration |
| partner/oem/brick/boot libboot_board_brick.a |
| |
| The actual bootloader: |
| |
| boot/bootloader bootloader |
| |
| |
| The product_config.mk defines three important build variables: |
| |
| DEVICE_BOOTLOADER_LIBS := \ |
| libboot_board_brick.a \ |
| libboot_arch_65002.a \ |
| libboot_arch_armv6.a |
| |
| DEVICE_BOOTLOADER_LINK_SCRIPT := \ |
| partner/semi/boot/boot.ld |
| |
| DEVICE_BOOTLOADER_INIT := \ |
| partner/semi/boot/init.S |
| |
| Which are used by the bootloader to specify which board and |
| architecture specific libraries to link against as well as what link |
| script and init.S to use |
