Dear Peter,
In message <1262301038.29396.137.camel@xxxxxxxxxxxxxxxxxxxxx> you wrote:
>
> > Why chose a different name at all? We could still call it "uImage",
> > meaning "U-Boot image" - U-Boot is clever enought o detect
> > automatically if we pass it an old style or a fit image.
>
> I agree with your point to an extent, but having 2 types of uImages is
> somewhat confusing to a user, even if U-Boot can differentiate between
> them. And if the legacy image and FIT image had the same Make target,
> how does a user specify which type they want to build? The fact that
> both "legacy" and FIT images would reside at arch/powerpc/boot/uImage
> doesn't make things any less confusing to Joe User.
Agreed.
> Currently U-Boot supports booting:
> 1 "legacy" uImages
> 2 "new" Flattened Image Tree (FIT) uImages
The "legacy" uImage format has a number of restrictions not unsimilar
to the restrictions we had in the bootloader / kernel interface when
using the old binary bd_info data structur. For the kernel interface
this has been replaced by using the device tree, and I would like to
see the same happen in U-Boot.
The "new" FIT image type should become the default, and old "legacy"
images should only be generated upon special request (i. e. if some-
one needs these for compatibility with an old, not yet FIT-aware
version of the boot loader).
> What do you think about changing the U-Boot documentation to rename
> those 2 image types to:
> 1 uImages
> 2 FIT Images
Let's make this "uImage.old" (or "uImage.legacy" similar) and
"uImage", then.
> The FIT image is a relatively generic image type - its just a blob that
> dtc created from a device tree and some input binaries. In my mind its
> not intimately tied to U-Boot, at least not conceptually. The "legacy"
Correct. The intention was to provide an open and somewhat
"standardized" format that can be easily extended for new
requirements, whatever these may be.
> uImages have to agree with U-Boot's header format defined in the U-Boot
> source code, so the uImage name does make sense with respect to the
> "legacy" uImages.
Well, you can read "uImage" as "universal Image", which kind of fits
the FIT approach :-)
> My vote would be to make the Linux FIT target rule "fitImage" and then
> update the U-Boot documentation to make obvious the differences between
> uImages and FIT images.
I think we should not try to support both legacy and FIT images on the
same level - the idea is clearly that legacy images is the old, to be
replaced format, while FIT images is the new, to be used as standard
format. In this sense I vote for using plain and simple "uImage" for
the (new) standard format, and marking the old format by some ".old"
or ".legacy" suffix.
BTW: note that (IIRC) we don't even have a formal definition of the
"FIT" abbreviation yet ;-)
Best regards,
Wolfgang Denk
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DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
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