Re: [PATCH] cmd: bcb: fix bcb struct alignment issue

[Mattijs Korpershoek <mkorpershoek@baylibre.com>]

Hi Gary,

Thank you for your patch.

Gary Bisson <gary.bisson@boundarydevices.com> writes:

> Without this patch the bcb struct could be located at an odd address
> which resulted in data not being copied to the buffer.
>
> Here was the repro steps (from Mattijs):
> => mmc dev 1
> => bcb load 1 misc
> => bcb dump command
> 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> => part start mmc 1 misc misc_start
> => mmc read ${loadaddr} ${misc_start} 4
> => bcb load 1 misc
> => bcb dump command
> 00000000: 62 6f 6f 74 6f 6e 63 65 2d 62 6f 6f 74 6c 6f 61
> 00000010: 64 65 72 00 00 00 00 00 00 00 00 00 00 00 00 00
>
> This behavior was observed on an Amlogic A311D (ARM64) platform with a
> recent GCC toolchain (11.2.0) but is most likely affecting other
> platforms.
>
> To avoid issues the structure is aligned on DMA minimum alignment value
> as it is passed directly to the read function.
>
> Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>
> ---
>  cmd/bcb.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # on khadas vim3

>
> diff --git a/cmd/bcb.c b/cmd/bcb.c
> index 6b6f1e9a2f1..92f4d27990d 100644
> --- a/cmd/bcb.c
> +++ b/cmd/bcb.c
> @@ -12,6 +12,7 @@
>  #include <log.h>
>  #include <part.h>
>  #include <malloc.h>
> +#include <memalign.h>
>  
>  enum bcb_cmd {
>  	BCB_CMD_LOAD,
> @@ -24,7 +25,7 @@ enum bcb_cmd {
>  
>  static int bcb_dev = -1;
>  static int bcb_part = -1;
> -static struct bootloader_message bcb = { { 0 } };
> +static struct bootloader_message bcb __aligned(ARCH_DMA_MINALIGN) = { { 0 } };
>  
>  static int bcb_cmd_get(char *cmd)
>  {
> -- 
> 2.34.1