[U-Boot-Users] Warning for mpc8360emds users: fdt-cmd from u-boot-fdt.git

Jerry Van Baren
2007-04-05T18:12:58Z

Bruce_Leonard at selinc.com wrote:
> Hi all
>
> u-boot-users-bounces at lists.sourceforge.net wrote on 04/05/2007 04:00:15
> AM:
>
>> Wolfgang Denk wrote:
>>> In message <46146842.8060509@gmail.com> you wrote:
>>>> If bootm edits/augments the FDT, the boot scripts/user has no chance
> to
>>>> change the items it edits/augments (biggie: the chosen node), or even
>
>>>> print it before linux is launched. This defeats 90% of the purpose
> of
>>>> the fdt command - allowing the user/script customize the blob before
>>>> linux is launched.
>>> I agree that it should be *possible* to do this, if wanted.Similar
>>> like we can set up our own contents of thebootargs variable.
>>>
>>> On the other hand, bootm should do everything that is necessary to
>>> start a kernel without such interaction, if needed.
>>>
> <snip snip>
>
> My two cents worth (for what it's worth :-/): from the standpoint of
> someone using uboot for the first time and having to learn from the ground
> up without the benefit of having used this stuff for many years, I agree
> with Wolfgang. It took me two weeks just to figure out what a device tree
> is and that I even needed one. It took me two more days to figure out how
> to create the blob and how to use it. I still don't know the details of
> DTS files, what needs to be in them or what the different fields mean.
> Adding another step/level of obscurity with REQUIRING the use of fdt
> commands and/or scripts is just another barrier to new users. And I have
> to tell you, this thing is a bear to learn. For folks who have been
> digging around in the guts of it, I'm sure it's trivial. But I at least
> am pretty overwhelmed by it.
>
> I think it would be great to have the option of using the ftd commands if
> it suited your purpose, but still be able to use things as they currently
> are. That would be the most flexible, give the expert users something
> they want, and not add yet another thing that new people HAVE to learn
> just to get an OS to boot.
>
> Again just my 2 cents. Flames welcome.
>
> Bruce

Yes, but now you are worth 5 figures more: expect a $00,000 raise as
part of your next performance appraisal.

I plan to implement Andy Fleming's suggestion which will resolve the issue:
> > What if we made it so if there isn't a chosen node in the blob when
> > bootm is called, it fills in a default one. This prevents some odd
> > failures, and allows people to continue using device trees in the
> > current manner, while still enabling the extra flexibility.

gvb
Pedantic Script: device trees and blobs are kernel things, they ain't
our fault. :-P Yet. ;-)