[U-Boot] [PATCH] Add support for setting environment variable from RAM.
Eric Nelson
eric.nelson at boundarydevices.com
Tue Feb 3 19:56:46 CET 2009
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
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