[U-Boot] [PATCH v2 1/3] image: Make image_get_fdt work like image_get_{ram_disk, kernel}

Wolfgang Denk
2011-11-06T08:57:05Z

Dear Simon Glass,

In message <CAPnjgZ2mKwMyYVyGyYwMm8dNMfNPwgbJA+YTH_G1X-uzbkDfpQ@mail.gmail.com> you wrote:
>
> Searching for "DTB append ARM zImage" provides lots of recent
> activity. The justification for this series seems to be old boot
> loaders. ...

True. In my understanding, this is only relevant to less capable boot
loaders (which not always are old - things like UEFI are not much
better in this respect). But U-Boot has full DT support, and we are
even on the way to configure U-Boot itself through a DT, so we should
at least optionally be able to use these features.

> ... Is there a LKML thread about why it should/shouldn't be done
> in U-Boot specifically - other boot loaders may require the kernel to
> do it, but for U-Boot there would need to be some sort of reason I
> think.

I cannot see a single reason for such format in U-Boot context. We
have been using the device tree for years on PPC, and never had any
such need. Dt is actually standard technology now. It's only new for
ARM, like all the other stuff as FPU support, cache coherency, PCI,
SMP, ... you name it.

> I am currently using a hybrid solution (U-Boot loads the zImage and
> DTB, then kernel decompresses zImage) and we have discussed changing
> this. It may need a new build target in the kernel, but not rocket
> science.

Patches for this have been submitted (and rejected) several times,
years ago. Ditto for other useful things (like being able to pass the
kernel a ramdisk / initrd address in NOR flash, so we can avoid
copying it into RAM first). Search the ML archives if you are
interesteed.

Best regards,

Wolfgang Denk

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