[U-Boot] [PATCHv1 02/22] arm: socfpga: enable saveenv to mmc partition

[Stefan Roese]

On 15.01.2015 23:08, Marek Vasut wrote:
> On Thursday, January 15, 2015 at 11:00:00 PM, Pavel Machek wrote:
>>> diff --git a/include/configs/socfpga_common.h
>>> b/include/configs/socfpga_common.h index 6b1f967..673377b 100644
>>> --- a/include/configs/socfpga_common.h
>>> +++ b/include/configs/socfpga_common.h
>>> @@ -281,9 +281,12 @@ unsigned int cm_get_qspi_controller_clk_hz(void);
>>>
>>>   #define CONFIG_SYS_CONSOLE_IS_IN_ENV
>>>   #define CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
>>>   #define CONFIG_SYS_CONSOLE_ENV_OVERWRITE
>>>
>>> -#define CONFIG_ENV_IS_NOWHERE
>>>
>>>   #define CONFIG_ENV_SIZE			4096
>>>
>>> +#define CONFIG_ENV_IS_IN_MMC
>>> +#define CONFIG_SYS_MMC_ENV_DEV		0/* device 0 */
>>> +#define CONFIG_ENV_OFFSET		512/* just after the MBR */
>>> +
>>
>> Would it make sense to make environment bigger (64K?) at this point,
>> and enabling the redundant environment option, so that one bad block
>> does not bring the whole device down?
>
> Do you think you'll ever have more than a 4KiB of text data in the env ?

I have used bigger environment in some cases.

> I can see a reason for some 16 KiB environment, but that's the ceiling.

Then lets switch to at least 8KiB please.

Pavel, would be 8KiB enough for your project?

> Usually, the env only has to be a few KiB and it's size has to be multiple
> of the underlying device's erase block. But in case of SD card, there are no
> explicit erase blocks exported to the user, all is hidden by the controller
> in the SD card and gives an illusion of a device which has 512b blocks and
> the user doesn't care for bad block management. Since the controller in the
> card does the bad block management and wear leveling/relocation of blocks,
> it also means that in case the controller did fail to provide the block which
> contains env, the whole card would already be in a very bad state.

Right. Nevertheless it makes sense to support the redundant envrionment 
(at least from my point of view), regardless of the device the 
evironment is stored in. Thinking for example about power-supply failure 
(power-cut) while writing into the one envrionment version.

Thanks,
Stefan