On Fri, 2007-12-07 at 08:14 -0500, Jerry Van Baren wrote:
Joakim Tjernlund wrote:
[snip]
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.
[SNIP]
FWIIW, while I appreciate and agree with Wolfgang's points, I don't see why we cannot add Joakim's configuration tweak. It is a pretty minor issue and, if he finds it useful, perhaps it would be useful to others.
Having said that, the patch could be made better by IMHO using the #ifdef logic embedded rather than defining DEFAULT_OF_TREE to NULL if it isn't already defined:
#if defined(CONFIG_OF_FLAT_TREE) || defined(CONFIG_OF_LIBFDT) #ifdef DEFAULT_OF_TREE char *of_flat_tree = DEFAULT_OF_TREE; #else char *of_flat_tree = NULL; #endif ulong of_data = 0; #endif
Also, we should have an update to the README to explain that DEFAULT_OF_TREE can be defined in the board-specific config file to be the address of a FDT embedded in u-boot or a function that builds/modifies a FDT and returns the address.
This should probably go somewhere in the section on LIBFDT line 332 ff. (I would put it at line 342, your line numbers may vary). http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot/u-boot-fdt.git;a=blob;f=README;h=09eb76fe4528dfedca027b119ac760fce2570e35;hb=HEAD#l341
Best regards, gvb
Made a new patch with Jerrys comments addressed. Also renamed DEFAULT_OF_TREE to CFG_OF_TREE. OK?
From 2f20cc2bb5eddd1ef06671ebf2080aadd8694e58 Mon Sep 17 00:00:00 2001
From: Joakim Tjernlund Joakim.Tjernlund@transmode.se Date: Sun, 9 Dec 2007 14:06:32 +0100 Subject: [PATCH] Add CFG_OF_TREE knob.
Make it possible to construct a OF tree from board code. See README for details.
Signed-off-by: Joakim Tjernlund Joakim.Tjernlund@transmode.se --- README | 8 ++++++++ common/cmd_bootm.c | 4 ++++ 2 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/README b/README index 3dad5fc..8bd70bf 100644 --- a/README +++ b/README @@ -340,6 +340,14 @@ The following options need to be configured: * Adds the "fdt" command * The bootm command automatically updates the fdt
+ CFG_OF_TREE + * Define this to a function in board code to construct + your own OF tree. The function should return a char * + pointing to your OF tree. + Useful if you have multiple OF trees or want to build your + tree dynamically. You can still overide this tree by + passing a OF tree to bootm. + CONFIG_OF_FLAT_TREE * Deprecated, see CONFIG_OF_LIBFDT * Original ft_build.c-based support diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c index d816349..68dfb59 100644 --- a/common/cmd_bootm.c +++ b/common/cmd_bootm.c @@ -527,7 +527,11 @@ 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) +#ifdef CFG_OF_TREE + char *of_flat_tree = CFG_OF_TREE; +#else char *of_flat_tree = NULL; +#endif ulong of_data = 0; #endif