Hello Wolfgang,
Wolfgang Denk wrote:
Dear Albert ARIBAUD,
In message 4CCEF2E4.5080003@free.fr you wrote:
Also, I understand why the second RFC change I did was harmful to tx25. Contrary to u-boot itself, u-boot-spl is not compiled to be position independent; it actually loads at a given address then copies itself, without relocating, to its home location.
It copies _itself_? Not the U-Boot payload?
Heiko, is this intentional? Do we really first load the whole image, then copy the U-Boot payload to some other address, then relocate it to yet another one?
- preloader copies first page of nand (nand_spl code) to 0xbb000000 (some cpu internal mem) and jumps to this address - nand_spl does lowlevelinit, relocate itself to TEXT_BASE (nand_spl code) - from there, it copies u-boot code from nand to CONFIG_SYS_NAND_U_BOOT_DST and jumps to CONFIG_SYS_NAND_U_BOOT_START - u-boot run into board_init_f, calculates new relocation address and relocates ...
But there is a possibility to prevent one copy, if TEXT_BASE = relocation address = CONFIG_SYS_NAND_U_BOOT_DST
In this case nand_spl code copies u-boot from nand to CONFIG_SYS_NAND_U_BOOT_DST. As this is equal to the relocation address, no need to copy code in relocate_code().
But as codesize changes (and with it relocation address) this is not a perfect solution.
bye, Heiko