On 2016-08-11 12:39, Andreas Fenkart wrote:

56086921 added support for unaligned environments access. U-boot itself does not support this:

• env_nand.c fails when using an unaligned offset. It produces an error in nand_erase_opts{drivers/mtd/nand/nand_util.c}
• in env_sf/env_flash the unused space at the end is preserved, but not in the beginning. block alignment is assumed
• env_sata/env_mmc aligns offset/length to the block size of the underlying device. data is silently redirected to the beginning of a block

There is seems no use case for unaligned environment. If there is some useful data at the beginning of the the block (e.g. end of u-boot) that would be very unsafe. If the redundant environments are hosted by the same erase block then that invalidates the idea of double buffering. It might be that unaligned access was allowed in the past, and that people with legacy u-boot are trapped. But at the time of 56086921 it wasn't supported and due to reasons above I guess it was never introduced. I prefer to remove that (unused) feature in favor of simplicity

I also don't see any value supporting unaligned environment, so FWIW:

Acked-by: Stefan Agner stefan.agner@toradex.com

Small nit below:

Signed-off-by: Andreas Fenkart andreas.fenkart@digitalstrom.com

tools/env/fw_env.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)

diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c index 6b0dcaa..d2b167d 100644 --- a/tools/env/fw_env.c +++ b/tools/env/fw_env.c @@ -1294,6 +1294,18 @@ static int check_device_config(int dev) struct stat st; int fd, rc = 0;

• if (DEVOFFSET(dev) % DEVESIZE(dev) != 0) {

• fprintf(stderr, "Environment does not start on erase block boundary\n");
  

Erase block is sometwhat confusing in the MMC context, maybe parenthesize "erase"?

-- Stefan

• errno = EINVAL;
  

• return -1;
  

• }
• if (ENVSIZE(dev) > ENVSECTORS(dev) * DEVESIZE(dev)) {

• fprintf(stderr, "Environment does not fit into available sectors\n");
  

• errno = EINVAL;
  

• return -1;
  

• }
• fd = open(DEVNAME(dev), O_RDONLY); if (fd < 0) { fprintf(stderr,