[U-Boot] env: mmc: Fix misaligned buffer address when saving envvars to FAT

[Tom Rini]

On Thu, May 17, 2018 at 01:19:41PM +0530, Vipul Kumar wrote:

> From: Gary Mussar <gmussar at ciena.com>
> 
> When doing a u-boot saveenv with the environment in FAT we see the
> following warning:
> 
> ZynqMP> saveenv
> Saving Environment to FAT...
> writing uboot.env
> FAT: Misaligned buffer address (000000007deb9b60)
> done
> 
> This can be eliminated by aligning the environment to an appropriate
> boundary.
> 
> Signed-off-by: Gary Mussar <gmussar at ciena.com>
> Signed-off-by: Vipul Kumar <vipul.kumar at xilinx.com>
> ---
>  include/environment.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> --
> 2.7.4
> 
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> 
> diff --git a/include/environment.h b/include/environment.h
> index 50c62c5..d6c530d 100644
> --- a/include/environment.h
> +++ b/include/environment.h
> @@ -150,7 +150,11 @@ typedef struct environment_s {
>         unsigned char   flags;          /* active/obsolete flags        */
>  #endif
>         unsigned char   data[ENV_SIZE]; /* Environment data             */
> -} env_t;
> +} env_t
> +#ifdef ARCH_DMA_MINALIGN
> +__aligned(ARCH_DMA_MINALIGN)
> +#endif
> +;
> 
>  #ifdef ENV_IS_EMBEDDED
>  extern env_t environment;

This needs some more work.  The first problem is that ARCH_DMA_MINALIGN
is defined for all platforms.  But it might not be defined in all uses,
for example M5485BFE and other cases of embedded in the binary
environment.  And if we drop the check for ARCH_DMA_MINALIGN existing we
run into problems with needing to add __align to include/compiler.h.

My guess is that what we should do here is that we have another case in
env/fat.c (there's already one) where a variable needs to be __aligned
properly instead.  Can you look down that path?  Thanks!

-- 
Tom
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