[U-Boot] [PATCH] Add support for setting environment variable from RAM.

[Eric Nelson <eric.nelson@boundarydevices.com>]

Hello Peter,

Peter Tyser wrote:
> Hi Eric,
> 
> On Tue, 2009-02-03 at 08:28 -0700, Eric Nelson (Boundary Devices) wrote:
>>  /************************************************************************
>> + * Set a new environment variable from RAM.
>> + * Requires three arguments: the variable name, a memory address and a length.
>> + *
>> + * Deletes the environment variable if the length is zero.
>> + */
>> +int do_ramenv(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
>> +{
>> +	unsigned long len, i;
>> +	char *addr;
>> +
>> +	if (argc != 4) {
>> +		cmd_usage(cmdtp);
>> +		return 1;
>> +	}
>> +	addr = (char *)simple_strtol(argv[2], NULL, 16);
>> +	len = simple_strtol(argv[3], NULL, 16);
>> +	if (!addr || !len) {
>> +		cmd_usage(cmdtp);
>> +		return 1;
>> +	}
>> +	addr[len] = '\0';
>> +	for (i = 0; i < len; i++) {
>> +		/* turn newlines into semicolon */
>> +		if (addr[i] == '\n')
>> +			addr[i] = ';'; /* ignore dos-style newlines */
>> +		if (addr[i] == '\r')
>> +			addr[i] = ' '; /* accept sh-comments and discard them */
>> +		if (addr[i] == '#') {
>> +			while (addr[i] && addr[i] != '\n')
>> +				addr[i++] = ' ';
>> +			i--;
>> +		}
>> +	}
>> +	setenv(argv[1], addr);
>> +	return 0;
>> +}
>> +
>> +/************************************************************************
>>   * Look up variable from environment,
>>   * return address of storage for that variable,
>>   * or NULL if not found
>> @@ -605,6 +643,14 @@ U_BOOT_CMD(
>>  	"    - delete environment variable 'name'\n"
>>  );
>>  
>> +U_BOOT_CMD(
>> +	ramenv, 4, 0, do_ramenv,
>> +	"ramenv  - get environment variable from ram\n",
> 
> The "ramenv  - " and "\n" are no longer used in the above line.
> 

Oops. Can you tell I started by implementing this on an older source tree?

Re-reading it, the comment should probably also say "set environment variable
from ram" instead of "get...".

If there's interest, I'll happily re-submit the patch.

>> +	"name addr maxlen\n"
>> +	"    - set environment variable 'name' from addr 'addr'\n"
>> +	"    - delete environment variable if maxlen is 0\n"
>> +);
>> +
>>  #if defined(CONFIG_CMD_ASKENV)
>>  
>>  U_BOOT_CMD(
> 
> In the email thread you mentioned above, Detlev mentions 2 alternatives
> to the "ramenv" command - loading a uImage script and running it via
> autoscr, or modifying autoscr to be able to raw files (non-uImages).
> Both of these methods seem cleaner and more flexible at a glance.  Is
> there a specific reason using autoscr wouldn't work for your setup?
> 
The customer requesting this feature operates in a regulated environment with
pretty strict rules about separation of code and data. Autoscr is kind of
a big stick for what we're trying to achieve: (configuring an LCD with
settings from a file on SD card).

> For example, what is the process to load multiple environment variables
> with the ramenv command?  If I understand correctly, in order to load 10
> environment variables you'd have to repeat the process of "load a file
> to RAM, run ramenv" 10 times?  That seems much more difficult than
> loading 1 file with 10 environment variables and running autoscr once.
> 
That's certainly true, although once you have an environment variable you
could use it for iteration...

Our particular need is just for a single environment variable, so the
update works pretty well. I started by updating our 'lcdpanel' U-Boot
command to read from file, but this is much more useful.

> Best,
> Peter
>

Regards,


Eric