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

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

• 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,