[U-Boot-Users] [PATCH] Fix initrd booting

[Jerry Van Baren <gvb.uboot@gmail.com>]

Hi Andy,

I'm not sure if you are aiming this at u-boot-fdt, which would be 
logical, or if you are aiming this at u-boot-testing (or other).  Care 
to clarify?

Andy Fleming wrote:
> The device tree needs to be passed to Linux within CFG_BOOTMAPSZ.
> The current code places the device tree right before the initrd
> if it exists, and that will usually be closer to the end of
> memory.  Instead, we should always put the device tree right
> before the bd_info structure, thus ensuring it is within
> CFG_BOOTMAPSZ.
> 
> We do, however, allow for FDTs in uImages to shoot themselves in
> the foot by requesting a location outside of CFG_BOOTMAPSZ.
> 
> Signed-off-by: Andy Fleming <afleming@freescale.com>
> ---
>  common/cmd_bootm.c |   20 ++++++++------------
>  1 files changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
> index a6499e8..d12ef76 100644
> --- a/common/cmd_bootm.c
> +++ b/common/cmd_bootm.c
> @@ -753,10 +753,7 @@ do_bootm_linux (cmd_tbl_t *cmdtp, int flag,
>  #else
>  		if (*(ulong *)of_flat_tree == OF_DT_HEADER) {
>  #endif
> -#ifndef CFG_NO_FLASH
> -			if (addr2info((ulong)of_flat_tree) != NULL)
> -				of_data = (ulong)of_flat_tree;
> -#endif
> +			of_data = (ulong)of_flat_tree;

Is this right?  The logic in bootm *in general* and specifically here is 
hard to figure out, but the way I'm puzzling it out...
1) If of_data is *not* NULL, it is used as the indicator that the blob
      must be relocated.
2) The above is saying that, if there is flash (not defined CFG_NO_FLASH
      gaak) and if of_flat_tree points into flash (addr2info returns a
      pointer), then of_data is set which makes #1 true.

As I read it, this causes the blob to be copied to RAM if it is in 
flash, which is necessary since we cannot add/rewrite nodes and 
properties in a flash copy.

Your change causes the blob to _always_ be relocated.  Not necessarily 
bad, but is it always good?  I'm not a bootm expert by any means, and I 
suspect the complexity grew substantially over time, but in the mucking 
about I did, I did not dare to change the logic.  :-/

>  		} else if (ntohl(hdr->ih_magic) == IH_MAGIC) {
>  			printf("## Flat Device Tree Image at %08lX\n", hdr);
>  			print_image_hdr(hdr);

[snip]

Thanks,
gvb