Re: Linux on ARM: bootloader & remapping

Hello, Måns
You wrote on Wed, 17 Dec 2008 19:20:10 +0000:

MR> U-Boot already supports many arm926-based boards. Chances are yours
MR> only needs a bit of tweaking.

My concern is how to define a memory map and consequently a valid TEXT_BASE
value. For example, on my chip, after reset 0x0 and before remap points at
NOR flash, RAM is mapped to 0x1000_0000. Therefore, U-Boot image should be
linked to 0x0000_0000 address to properly start off the flash, i.e.
TEXT_BASE defined in $(uboot)/board/my_board/config.mk should be 0x00000000.

But uboot usually copies itself to RAM, which is at 0x1000_0000 in my
case -- it won't work as I understand, as my image is linked to 0x0000_0000.
Then if we do remap first (making RAM at 0x0000_0000), then copy image to
RAM, then there would not be a room for 'malloc' area and stack (which uboot
allocates at lower addresses), as we specified TEXT_BASE=0x0, and this is
the address U-Boot copies itself in memory at.

Perhaps I misunderstand something in a work of U-Boot...

-- Mark


.

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