[U-Boot] [help] how does u-boot passing ``fdt'' to linux kernel & where is cmd_line?

[Detlev Zundel <dzu@denx.de>]

Hi Wang,

>>> the code is from arch/powerpc/boot/cuboot-bamboo.c, and the kernel is
>>> 2.6.30.1, the boot image I'm using is something like cuImage.bamboo, I
>>> checked zImage.ld.S, and found that when we're running cuImage.bamboo,
>>> we actually fall into arch/powerpc/boot/crt0.S:_zimage_start(), which
>>> will call platform_init() and then bamboo_init() finally. but sounds
>>> like if we passing r3 as fdt, then the code (platform_init, etc.., and
>>> even arch/powerpc/kernel/head_xxx.S start() function, only comments,
>>> though) is actually wrong, isn't it? Thank you very much for help.
>>
>> This is the boot wrapper code only used if you are trying to boot a new
>> kernel w/an old u-boot. ?If you are using a current u-boot you should just
>> be using a plain old uImage as produced by the kernel build.
>
> do you mean the default ``uImage'' file? I'm using u-boot-2009.06, and
> I can boot successfully with cuImage.mpc8548cds (I'm actually working
> on a mpc8548 cds board), but unable to boot ``uImage'', I'm sure the
> ``vmlinux'' is the same.

Booting such a new kernel, you'll need to pass an adress of an fdt too:

=> help bootm
bootm [addr [arg ...]]
    - boot application image stored in memory
    passing arguments 'arg ...'; when booting a Linux kernel,
    'arg' can be the address of an initrd image
    When booting a Linux kernel which requires a flat device-tree
    a third argument is required which is the address of the
    device-tree blob. To boot that kernel without an initrd image,
    use a '-' for the second argument. If you do not pass a third
    a bd_info struct will be passed instead

So try "bootm <kernel> - <fdt>"

Cheers
  Detlev

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