-----Original Message----- From: wd@denx.de [mailto:wd@denx.de] Sent: den 4 december 2007 01:24 To: Joakim Tjernlund Cc: 'Darcy Watkins'; u-boot-users@lists.sourceforge.net Subject: Re: [U-Boot-Users] Can U-boot Autodetect arch/ppc versusarch/powerpc from info in the uImage?
Dear Jocke,
in message 057d01c83604$e0bb9ce0$5267a8c0@Jocke you wrote:
Wolfgang, have you read the "Passing the OF tree to bootm
from board code?"
thread? Would you mind explain why it was removed and why
you don't think
it should be in u-boot?
Is there a thread to it? I can just find a single posting from you, without any replies...
Yes, there were a few replies.
But as for your question:
I cannot remember that, or when, or why exactly this feature was removed; I cannot even remember that it ever exited.
Was a long time ago, I too can't recall details.
But in genral I think it is a very bad idea to compile the device tree into the U-Boot image, because that means you can never replace / change / update it. Also I fail to understand why you would want to do that. To me it seems much more sensible to have separate U-Boot and device tree images, which can be replaced independent of each other. If you want, you can still store these in adjacent locations in flash. You can even attach these (you probably want to insert some padding to align on flash sector boundaries) images to for a single file which can be downloaded and flashed in a single operation.
I create a template tree that is compiled into u-boot. Then runtime code adjusts/amends the tree as needed for that particular board. We do have many diffrent boards that more or less look the same to u-boot and kernel. For all these boards I do only one u-boot/kernel that runs on all boards. Reason for that is too ease SW updates and save space. This might not be the best methond of doing things but thats how it has been the last 7 years so it is not something that is easy to change now.
Even if the above method isn't something you want in u-boot I still think there should be a way to pass the dev. tree to the bootm command without using the environment/command arguments. For instance if one has several trees, board code should be able decide which tree to use. Command args should still overide this builtin tree.
Jocke
As far as I understand your request, this offers all the same options you can get with a compiled in device tree blob, but with the added benefit of allowing many more things at the same time, too.
Maybe I'm missing something?
Best regards,
Wolfgang Denk
-- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de Behind every great man, there is a woman -- urging him on. -- Harry Mudd, "I, Mudd", stardate 4513.3