Standardize on run-time board ID variables

Hi Tom,

Quoted 45 lines · Tom Rini

Quoted 43 lines · Stephen Warren

Quoted 29 lines · Tom Rini

Quoted 21 lines · Stephen Warren

Quoted 11 lines · Tom Rini

Hey all,

I've been thinking about one of the problems we need to solve over in TI AM335x land and that is given that we support a number of different boards with a single binary (and we have an i2c eeprom that tells us what board and revision we are on), the user needs to be able to easily determine what board we are on so they know what dtb file to load so they can boot. To this end I've added CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG to the README which says when set we have board_name and board_rev set at run-time. Then for am335x[1]

With CONFIG_ENV_VARS_UBOOT_CONFIG set, there's a environment variable named $board that indicates which board U-Boot is running on (and other related variables). The idea is that the user can:

fsload ${devtype} ${devnum}:${rootpart} ${fdt_addr_r} \
/boot/${soc}-${board}.dtb

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Now, CONFIG_ENV_VARS_UBOOT_CONFIG sets $board at compile-time, since the config variable was created in the context on a U-Boot that runs on a single board. However, I see no reason why we can't maintain the user-visible results of this config option even in other cases, so that everything is consistent to the user

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This works assuming that board maps to the device tree name. A bit more below...

True. I've made sure of that for Tegra.

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To that end, can we make CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG set $board instead of $board_name?

I had talked with Joe about this on IRC briefly and he seemed to be against overwriting "board"

Why is that? Perhaps alternatively, CONFIG_ENV_VARS_UBOOT_CONFIG should set both board and a default value for board_name.

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Joe?

It think in the use-case that you are talking about (multiple boards, one binary) the board from the build of the binary could still be useful to know in addition to the run-time-determined board name and rev. I think it would also be useful to have the "target" available in the env for the same reason. Tom and I also discussed this on IRC.