[RFC] Kbuild support for ARM FIT images

[Tom Rini]

On 02/21/2013 09:37 AM, Russell King - ARM Linux wrote:
> (Dropped uboot mailing list because it constantly holds my mails for
> moderation.)
> 
> On Thu, Feb 21, 2013 at 09:08:58AM -0500, Tom Rini wrote:
>> On 02/21/2013 08:46 AM, Russell King - ARM Linux wrote:
>>> We're about to make it harder how?  By forcing them to use DT
>>> blobs? Or by forcing them to have to use the combined zImage + DT
>>> format because their boot loaders are soo broken that they can't
>>> deal with multiple images?
>>
>> None of that.  We're making it harder since most folks don't have a
>> board with 'bootz' built-in and the 'uImage' target doesn't build now
>> (unless, yes, you pass LOADADDR to make) so they either format it by
>> hand (/ adjust their local scripting) or do what you're doing.
> 
> And adjusting their process to pass an additional argument to the
> kernel make is too difficult?
> 
> So instead we have to change the kernel makefiles and scripting to
> create yet another uboot specific format, which is going to need
> them to edit their scripts in a much more invasive way _anyway_?
> 
> "or do what you're doing" - oh you mean, adding an additional column
> to the database configuration, digging out from the kernel git
> history what the load addresses should be, updating the database tables
> with that, editing the build system scripts to extract this new column
> from the database, and pass it into make... yes, complicated isn't it.
> Didn't take long to sort out though, and didn't require a load of new
> file formats to fix.

Shrug.  Time will tell if everyone adopts as easily as you have.

>>> Yes, things have become a _little_ harder since OMAP has switched
>>> to multiplatform, but it really isn't that bad.  My build and boot
>>> test system still works, and it uses uImage for all the OMAP
>>> platforms. You just have to give the right LOADADDR= argument to
>>> the kernel to make the uImage generation work again.  Sure, the
>>> resulting uImage can't be loaded at a different address, but you if
>>> you need to change that, you can quite easily move the existing
>>> uImage out and re-run make ARCH=arm uImage LOADADDR=<something
>>> else> and hey presto, you end up with the uImage generated for a
>>> different address.
>>>
>>> But: we wouldn't be in this situation if it weren't for these
>>> absurd uboot uImage formats in the first place.  Or even be needing
>>> this FIT stuff if zImage was just used directly.
>>
>> FIT isn't required.  FIT is just trying to offer a nice usability
>> thing to folks.  A point of device trees is a single image works in a
>> lot of places.  FIT gives you a single file works in a lot of places.
> 
> Well, FIT isn't everywhere either.  So really that argument doesn't
> stand for the same reasons that bootz support isn't everywhere either.
> 
> My SDP4430's uboot provided by TI uses uboot 1.1.4.  Therefore, it
> doesn't support FIT, nor bootz - only uImage.

Because I can easily see TI having given you an "odder" than usual
board, I won't suggest you simply run mainline U-Boot instead (and
enable CONFIG_CMD_BOOTZ).  I was wondering how old what we gave you was
tho, sigh.

>>> uboot dug _itself_ into this hole.  It's uboot's problem.
>>
>> A whole lot  of people dug this particular hole.  Joel is trying to
>> offer up a solution that maybe makes things easier for everyone.  Or
>> it gets rejected here too and distros will come up with their N
>> different ways to try and provide easier experiences to the end user.
> 
> FIT just propagates the "boot loader specific file format" absurdity
> which was a mistake when uImage came along...

Would you feel better about it if something else parsed FIT too?

-- 
Tom