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- Summary
- =======
- The README is for the boot procedure used for TI's OMAP-L138 based
- hawkboard. The hawkboard comes with a 128MiB Nand flash and a 128MiB
- DDR SDRAM along with a host of other controllers.
- The hawkboard is booted in three stages. The initial bootloader which
- executes upon reset is the Rom Boot Loader(RBL) which sits in the
- internal ROM of the omap. The RBL initialises the memory and the nand
- controller, and copies the image stored at a predefined location(block
- 1) of the nand flash. The image loaded by the RBL to the memory is the
- AIS signed nand_spl image. This, in turns copies the u-boot binary
- from the nand flash to the memory and jumps to the u-boot entry point.
- AIS is an image format defined by TI for the images that are to be
- loaded to memory by the RBL. The image is divided into a series of
- sections and the image's entry point is specified. Each section comes
- with meta data like the target address the section is to be copied to
- and the size of the section, which is used by the RBL to load the
- image. At the end of the image the RBL jumps to the image entry
- point.
- The secondary stage bootloader(nand_spl) which is loaded by the RBL
- then loads the u-boot from a predefined location in the nand to the
- memory and jumps to the u-boot entry point.
- The reason a secondary stage bootloader is used is because the ECC
- layout expected by the RBL is not the same as that used by
- u-boot/linux. This also implies that for flashing the nand_spl image,
- we need to use the u-boot which uses the ECC layout expected by the
- RBL[1]. Booting u-boot over UART(UART boot) is explained here[2].
- Compilation
- ===========
- Three images might be needed
- * nand_spl - This is the secondary bootloader which boots the u-boot
- binary.
- hawkboard_nand_config
- The nand_spl ELF gets generated under nand_spl/u-boot-spl. This
- needs to be processed with the AISGen tool for generating the AIS
- signed image to be flashed. Steps for generating the AIS image are
- explained here[3].
- * u-boot binary - This is the image flashed to the nand and copied to
- the memory by the nand_spl.
- hawkboard_config
- * u-boot for uart boot - This is same as the u-boot binary generated
- above, with the sole difference of the CONFIG_SYS_TEXT_BASE being
- 0xc1080000, as expected by the RBL.
- hawkboard_uart_config
- Flashing the images to Nand
- ===========================
- The nand_spl AIS image needs to be flashed to the block 1 of the
- Nand flash, as that is the location the RBL expects the image[4]. For
- flashing the nand_spl, boot over the u-boot specified in [1], and
- flash the image
- => tftpboot 0xc0700000 <nand_spl_ais.bin>
- => nand erase 0x20000 0x20000
- => nand write.e 0xc0700000 0x20000 <nand_spl_size>
- The u-boot binary is flashed at location 0xe0000(block 6) of the nand
- flash. The nand_spl loader expects the u-boot at this location. For
- flashing the u-boot binary
- => tftpboot 0xc0700000 u-boot.bin
- => nand erase 0xe0000 0x40000
- => nand write.e 0xc0700000 0xe0000 <u-boot-size>
- Links
- =====
- [1]
- http://code.google.com/p/hawkboard/downloads/detail?name=u-boot_uart_ais_v1.bin
- [2]
- http://elinux.org/Hawkboard#Booting_u-boot_over_UART
- [3]
- http://elinux.org/Hawkboard#Signing_u-boot_for_UART_boot
- [4]
- http://processors.wiki.ti.com/index.php/RBL_UBL_and_host_program#RBL_booting_from_NAND_and_ECC.2FBad_blocks
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