[U-Boot] [RFC] arm926ejs: fix jump to RAM nand_boot

Albert ARIBAUD
2010-11-02T06:54:14Z

Le 02/11/2010 07:29, Heiko Schocher a ?crit :

> - 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

Heiko,

Since SPL is loaded in internal RAM, and since U-BOOT itself is loaded
only in DRAM, why does SPL need to relocate itself? Can it not run
entirely from IRAM and then jump to U-BOOT?

If SPL needs to relocate, then why does it run only the copy loop but
not the fixups loop?

Amicalement,
--
Albert.