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

Wolfgang Denk
2011-11-05T21:53:02Z

Dear Simon Glass,

In message <CAPnjgZ0bbhvZ1VPwY=0y9YZJdf+EOBgyKKVPFuAkBqy2z4L3HA@mail.gmail.com> you wrote:
>
> Just a quick Q. What is the ultimate intent here? Should we be aiming
> to have U-Boot copy and decompress the data into RAM ready for Linux?

Yes.

Rigth from the beginning of PPCBoot / U-Boot we designed it that
U-Boot would do all needed steps to verify, load and uncompress an
image. It make no sense to attach the uncompression and loading code
to each and every image, and to download it and store it again and
again and again. This works really well for example on Power, only
ARM is one of the examples where the PTB never bothered to acquaint
themself with ideas that went beyond the capabilities of Blob or
similar boot loaders.

> In theory this should be slightly faster since U-Boot already has the
> data in its cache. I think zImage now supports having an FDT inside
> but what is the advantage of zImage over a uImage with compressed
> portions?

There is none. Also, there is no advantage in attaching the DT blob
to the Linux image/. This is only of use to braindead boot loaders.

Best regards,

Wolfgang Denk

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