-----Original Message----- From: u-boot-users-bounces@lists.sourceforge.net [mailto:u-boot-users-bounces@lists.sourceforge.net] On Behalf Of Joakim Tjernlund Sent: den 4 december 2007 02:06 To: wd@denx.de Cc: u-boot-users@lists.sourceforge.net; 'Darcy Watkins' Subject: Re: [U-Boot-Users] Can U-boot Autodetect arch/ppcversusarch/powerpc from info in the uImage?
-----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?
Yes, here are some things to consider.
The extension I made can just as easily be a function that returns a dev. tree.
- One can have a dev. tree update procedure similar to rendundant env. The funktion then selects which dev. tree is valid and passes that back.
- The function can construct a dev. tree from builtin rules/code.
- One can even make it tftp a tree at boot and pass that back. Great in a development env. especially if you are debugging the dev. tree.
and the kicker is that you can still override this tree at runtime by passing a dev. tree argument to bootm.
All this will be possible by the simple patch I posted earlier, included below.
[PATCH] Make it possible to use a builtin OF tree. Signed-off-by: Joakim Tjernlund Joakim.Tjernlund@transmode.se --- common/cmd_bootm.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c index d816349..8405de7 100644 --- a/common/cmd_bootm.c +++ b/common/cmd_bootm.c @@ -507,6 +507,9 @@ fixup_silent_linux () #endif /* CONFIG_SILENT_CONSOLE */
#ifdef CONFIG_PPC +#ifndef DEFAULT_OF_TREE + #define DEFAULT_OF_TREE NULL +#endif static void __attribute__((noinline)) do_bootm_linux (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[], @@ -527,7 +530,7 @@ do_bootm_linux (cmd_tbl_t *cmdtp, int flag, void (*kernel)(bd_t *, ulong, ulong, ulong, ulong); image_header_t *hdr = &header; #if defined(CONFIG_OF_FLAT_TREE) || defined(CONFIG_OF_LIBFDT) - char *of_flat_tree = NULL; + char *of_flat_tree = DEFAULT_OF_TREE; ulong of_data = 0; #endif