[U-Boot-Users] Can U-boot Autodetect arch/ppcversusarch/powerpc from info in the uImage?

[Joakim Tjernlund]

> -----Original Message-----
> From: u-boot-users-bounces at lists.sourceforge.net 
> [mailto:u-boot-users-bounces at lists.sourceforge.net] On Behalf 
> Of Joakim Tjernlund
> Sent: den 4 december 2007 02:06
> To: wd at denx.de
> Cc: u-boot-users at 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 at denx.de [mailto:wd at denx.de] 
> > Sent: den 4 december 2007 01:24
> > To: Joakim Tjernlund
> > Cc: 'Darcy Watkins'; u-boot-users at 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 at 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 at 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
 
-- 
1.5.3.6

> > 
> > Best regards,
> > 
> > Wolfgang Denk