Re: [U-Boot] [PATCH 1/2] env: Fix env_load_location

On 08.02.2018 09:38, Maxime Ripard wrote:

Hi,

Thanks for your patch

On Wed, Feb 07, 2018 at 02:17:11PM -0800, York Sun wrote:

...

Commit 7d714a24d725 ("env: Support multiple environments") added static variable env_load_location. When saving environmental variables, this variable is presumed to have the value set before. In case the value was set before relocation and U-Boot runs from a NOR flash, this variable wasn't writable. This causes failure when saving the environment. To save this location, global data must be used instead.

Out of curiosity: which linker sections are affected of this issue? I assume only initialized data ('.data') is affected as it is left in place. Also, I assume that uninitialized data ('.bss') is not affected (as your linker can place this into ram)? If so, this issue could be fixed by changing ENVL_UNKNOWN to zero (which you already do in your patch) and leaving 'env_load_location' uninitialized, in which case it is initialized to zero (== ENVL_UNKNOWN) as defined by the C standard.

Another possibility to fix this would be to have your linker script put 'data' into ram but initialize it from rom. Something like this:

.data : {   <your section contents here> } >ram AT>rom

To me, both versions would be better than to add members to struct global_dat.

...

Signed-off-by: York Sun york.sun@nxp.com CC: Maxime Ripard maxime.ripard@free-electrons.com

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Limited test on LS1043ARDB.

env/env.c | 8 +++----- include/asm-generic/global_data.h | 1 + include/environment.h | 2 +- 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/env/env.c b/env/env.c index 9a89832..edfb575 100644 --- a/env/env.c +++ b/env/env.c @@ -62,8 +62,6 @@ static enum env_location env_locations[] = { #endif };

-static enum env_location env_load_location = ENVL_UNKNOWN;

• static bool env_has_inited(enum env_location location) { return gd->env_has_init & BIT(location);

@@ -108,11 +106,11 @@ __weak enum env_location env_get_location(enum env_operation op, int prio) if (prio >= ARRAY_SIZE(env_locations)) return ENVL_UNKNOWN;

• env_load_location = env_locations[prio];
  

• return env_load_location;
  

• gd->env_load_location = env_locations[prio];
  

• return gd->env_load_location;
  
  

  case ENVOP_SAVE:

• return env_load_location;
  

• return gd->env_load_location;
  

  }

  return ENVL_UNKNOWN;

diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h index fd8cd45..10f1441 100644 --- a/include/asm-generic/global_data.h +++ b/include/asm-generic/global_data.h @@ -51,6 +51,7 @@ typedef struct global_data { unsigned long env_addr; /* Address of Environment struct */ unsigned long env_valid; /* Environment valid? enum env_valid */ unsigned long env_has_init; /* Bitmask of boolean of struct env_location offsets */

• int env_load_location;

  unsigned long ram_top; /* Top address of RAM used by U-Boot */ unsigned long relocaddr; /* Start address of U-Boot in RAM */

diff --git a/include/environment.h b/include/environment.h index a406050..0f339da 100644 --- a/include/environment.h +++ b/include/environment.h @@ -188,6 +188,7 @@ enum env_valid { };

enum env_location {

• ENVL_UNKNOWN, ENVL_EEPROM, ENVL_EXT4, ENVL_FAT,

@@ -202,7 +203,6 @@ enum env_location { ENVL_NOWHERE,

ENVL_COUNT,

• ENVL_UNKNOWN,

Why did you need to change this? This looks a bit odd.

The global data struct is initialized to zero. I guess this change is meant to ensure 'gd->env_load_location' is initialized to ENV_UNKOWN (see my comments above).

Simon

Thanks! Maxime

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