Re: [PATCH v2 3/3] powerpc: Add support for ram filesystems in FIT uImages

From: Peter Tyser <ptyser@xes-inc.com>
To: Wolfgang Denk <wd@denx.de>
Cc: Grant Likely <grant.likely@secretlab.ca>,
	linuxppc-dev@ozlabs.org, linux-kbuild@vger.kernel.org
Subject: Re: [PATCH v2 3/3] powerpc: Add support for ram filesystems in FIT uImages
Date: Sun, 03 Jan 2010 17:52:46 -0600	[thread overview]
Message-ID: <4B412DCE.4030509@xes-inc.com> (raw)
In-Reply-To: <20100101104449.6DAC63F6FF@gemini.denx.de>

Hi Wolfgang,

> 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).

Agreed.

>> 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.

I'm in favor of keeping the old uImage format/naming the same, and 
calling the new image format a FIT Image.  ie no mention of uImage for 
FIT images.

<snip>

>> 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 :-)

I agree that the FIT image is a type of "universal Image", but I think 
"FIT image" is much more descriptive and accurate than "universal 
Image".  The FIT naming convention is designed to match device tree 
naming, which has lots of meaning.  eg:
   Flattened Device Tree (FDT) -> Flattened Image Tree (FIT)
   device tree source (.dts) -> image tree source (.its)
   device tree blob (.dtb) -> image tree blob (.itb)

>> 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.

Agreed.

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.

I disagree here.  I don't think calling FIT images "FIT uImages" adds 
much value and it would add confusion as there are now multiple uImage 
formats that a user needs to keep straight.  Keeping the legacy uImage 
naming/format the same, and calling the new FIT images "fitImage" (or 
possibly itbImage to line up with the dtbImage target) would make more 
sense to me.  Is there a compelling reason to keep the uImage word 
connected to FIT images?

Best,
Peter