Hello Stephen,
On 06/16/2014 09:52 PM, Stephen Warren wrote:
On 06/12/2014 03:46 AM, Przemyslaw Marczak wrote:
This patch introduces new feature: initialization of the dfu
bootloader entity from a separate environmental variable which
can be set on a boot time.
By default, DFU always check environmental variable: $dfu_alt_info.
Changes:
- DFU will also look for environmental variable: $dfu_alt_bootloader
- if any of dfu_alt_* variable is properly defined, then function
dfu_init_env_entities() will return success.
Use case:
Some devices can boot from various media type (SD, eMMC, NAND, etc.)
or some board configs are common for more than one board type.
In a such case, bootloader is probably placed on a different
devices or even offsets. So such DFU feature is welcome.
Why should the "dfu" command look at different environment variables?
Whatever code dynamically sets the value of $dfu_alt_bootloader should
simply set $dfu_alt_info instead.
Dynamically setting of any entity cold be done at boot time, like this:
# int buf_len = strlen(alt_bootloader) + strlen(CONFIG_DFU_ALT) + 4;
# char *buf = memalign(1, buf_len);
#
# sprintf(buf, "%s; %s", alt_bootloader, CONFIG_DFU_ALT);
# setenv("dfu_alt_info", buf);
But overwriting the $dfu_alt_info on each boot is not a good idea.
If user modify the dfu entities - then it will be overwritten at next boot.
In the other side I can store entities as $dfu_alt_default
and change the above code to:
# char *alt_default = getenv("dfu_alt_default");
# if (!alt_default)
# alt_default = "";
#
# int buf_len = strlen(alt_bootloader) + strlen(alt_default) + 4;
# char *buf = memalign(1, buf_len);
#
# sprintf(buf, "%s; %s", alt_bootloader, alt_default);
# setenv("dfu_alt_info", buf);
But then, there is some mess in the environment because of duplicated
default alt_info.
Those both, above solutions takes more time than just one simple line:
# setenv("dfu_alt_bootlaoder", CONFIG_SOME_ALT_INFO);
like in this patch set.
Maybe better could be modification of the function
dfu_init_env_entities() to support parsing variables
in the $dfu_alt_info instead of hard coded env variables
names, e.g:
dfu_alt_info="${alt_info_boot}, ${alt_info_system},..."
dfu_alt_info could be set with default variables names in each board
config file in the CONFIG_EXTRA_ENV_SETTINGS and then just one proper
variable could be set at boot, and others from env - simple and fast.
And then in the dfu init code - entities are initialized from env
variables - if they exists, like in the loop code from this patch.
I need some solution to automatically set proper bootloader entities,
since one binary can be stored on SD and eMMC cards.
Thank you,
--
Przemyslaw Marczak
Samsung R&D Institute Poland
Samsung Electronics
p.marc...@samsung.com
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