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On 10/24/12 12:21, Stephen Warren wrote:
On 10/24/2012 11:28 AM, Tom Rini wrote:
We add CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG, CONFIG_BOARD_LATE_INIT to set the variables and then fdtfile and findfdt to make us of this. It is now possible to do 'run findfdt' to have fdtfile be set to the value of the dtb file to load for the board we are running on.
diff --git a/arch/arm/cpu/armv7/am33xx/board.c b/arch/arm/cpu/armv7/am33xx/board.c
+#ifdef CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG + char safe_string[HDR_NAME_LEN + 1]; + + /* Now set variables based on the header. */ + strncpy(safe_string, (char *)header.name, sizeof(header.name)); + safe_string[sizeof(header.name)] = 0; + setenv("board_name", safe_string); + + strncpy(safe_string, (char *)header.version, sizeof(header.version)); + safe_string[sizeof(header.version)] = 0; + setenv("board_rev", safe_string); +#endif
By the way, is there any way to flag these variables as not being saved in the environment by saveenv? With the code above, the values will get over-written every time, so it's not such a big deal; the only issue is that the value needlessly gets saved into flash or uEnv.txt.
But what about a runtime-calculated variable that is only sometimes set? I suppose the answer there is to explicitly clear it if you aren't setting it.
Joe? Am I thinking right that your env work leads us down the path of being able to do this?
Or what about if the environment gets saved to uEnv.txt on an SD card which gets moved to a compatible but different board or board revision, running an older U-Boot that doesn't have this patch; then, the values stick around even though they're stale.
Yes, there's potential problems, but I think we can work around it or live with it. And FYI, uEnv.txt is (more or less) an un-mkimage'd boot.scr file :)
- -- Tom